U.S. patent number RE38,338 [Application Number 09/580,241] was granted by the patent office on 2003-12-02 for car electronic control system and method for controlling the same.
This patent grant is currently assigned to Hitachi Car Engineering Co., Ltd., Hitachi, Ltd.. Invention is credited to Mitsuru Kon'i, Tatsuya Yoshida.
United States Patent |
RE38,338 |
Yoshida , et al. |
December 2, 2003 |
Car electronic control system and method for controlling the
same
Abstract
A car remote control system utilizing a signal in the form of
electromagnetic wave or infrared ray called `keyless entry`. When
receiving a predetermined wake-up signal, an MPU is once operated
even when the received input signal is a noise signal to perform
only judging operation of whether or not the input signal is
normal. Only when judging that the input signal is a normal wake-up
signal, the MPU controllably causes an electronic circuit to be
shifted to a usual operation mode. When judging that the input
signal is the noise signal prior to full input of the tuner signal,
the MPU immediately shifts to a sleep mode. Thereby current
consumption of an electronic control circuit can be suppressed.
Inventors: |
Yoshida; Tatsuya (Ibaraki-ken,
JP), Kon'i; Mitsuru (Hitachinaka, JP) |
Assignee: |
Hitachi, Ltd. (Tokyo,
JP)
Hitachi Car Engineering Co., Ltd. (Hitachinaka,
JP)
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Family
ID: |
14892115 |
Appl.
No.: |
09/580,241 |
Filed: |
May 26, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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651559 |
May 22, 1996 |
5744874 |
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Reissue of: |
035863 |
Mar 6, 1998 |
06037675 |
Mar 14, 2000 |
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Foreign Application Priority Data
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May 24, 1995 [JP] |
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7-124707 |
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Current U.S.
Class: |
307/10.2;
180/287; 701/2; 340/12.5; 340/426.36 |
Current CPC
Class: |
B60R
16/0315 (20130101); G07C 9/00182 (20130101); B60R
2016/0322 (20130101); G07C 2009/00769 (20130101); Y02T
10/92 (20130101); G07C 2009/00261 (20130101) |
Current International
Class: |
B60R
16/02 (20060101); G07C 9/00 (20060101); H04Q
001/00 () |
Field of
Search: |
;307/9.1,10.1-10.8
;340/825.69,825.72,539,425.5,426,428,438 ;180/287
;701/2,3,6,49 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2 494 534 |
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May 1982 |
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EP |
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0 444 997 |
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Sep 1991 |
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EP |
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0570103 |
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Nov 1993 |
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EP |
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2494534 |
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May 1982 |
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FR |
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Primary Examiner: Fleming; Fritz
Attorney, Agent or Firm: Crowell & Moring LLP
Parent Case Text
This application is a continuation of application Ser. No.
08/651,559, filed May 22, 1996, now U.S. Pat. No. 5,744,874.
Claims
What is claimed is:
1. An electronic control apparatus for a car having a tuner
receiving a signal from a remote controller and a microcomputer
which activates at least one device when said tuner receives the
signal from said remote controller, comprising means for
intermittently supplying electric power to said tuner when a
control system of the car is not activated; the microcomputer being
provided with means for changing .[.the power.]. .Iadd.a
.Iaddend.supply .Iadd.of power .Iaddend.to said tuner into a normal
supply state and activating a function for monitoring an output
signal of the tuner when the microcomputer receives a wake-up
signal; and the microcomputer being provided with means for
outputting a wake-up request signal for waking a predetermined
device when the microcomputer has decided that the received
.Iadd.wake-up .Iaddend.signal is .[.the.]. .Iadd.a .Iaddend.normal
signal from the remote controller.
2. An electronic control apparatus for a car, comprising a tuner
which receives a signal from a remote controller and outputs a
predetermined signal to a microcomputer of an onboard controller,
means for the microcomputer to decide, when the microcomputer is
woken up by generation of a wake-up signal, whether the
.Iadd.generated .Iaddend.wake-up signal is supplied from the tuner;
means for the microcomputer to execute, when the .Iadd.generator
.Iaddend.wake-up signal is supplied from the tuner, a function for
determining whether the .Iadd.generated .Iaddend.wake-up signal is
generated due to noise; and means for activating, when the
generated wake-up signal is determined not to be due to noise, a
predetermined device by the microcomputer.
3. An electronic control apparatus for a car, comprising a tuner
which receives a signal from a remote controller and transmits a
signal to a microcomputer of an onboard controller, wherein an
output terminal of said .[.timer.]. .Iadd.tuner .Iaddend.is
connected to an input terminal of said microcomputer.[., to a
wake-us signal line of an output system.]. and to an input terminal
of a gate circuit, and an output terminal of said gate circuit is
connected to a wake-up terminal of said microcomputer.
4. An electronic control apparatus for a car having a tuner which
receives a signal from a remote controller, .[.said.]. .Iadd.and a
.Iaddend.microcomputer controlling and activating a device provided
in the car, comprising.Iadd.:.Iaddend. means for eliminating a high
frequency noise contained in an output signal of said tuner via a
software program executed by the microcomputer, the microcomputer
being configured to periodically sample a signal inputted to the
microcomputer from the tuner; means for checking the signal
inputted to the microcomputer and again checking the signal
inputted to the microcomputer after a set time shorter than
.[.the.]. .Iadd.a .Iaddend.sampling period and longer than a period
of the high frequency noise; and means for determining the
existence or absence of .[.a.]. .Iadd.the .Iaddend.noise on the
basis of a state of signal obtained by .[.the.]. periodic sampling
and .Iadd.by .Iaddend.checking of the microcomputer.
5. An electronic control method for a car having a tuner receiving
a signal from a remote controller and a microcomputer which
activates one or more devices provided in the car when said tuner
receives the signal from said remote controller, comprising the
steps of intermittently supplying electrical power to the tuner
when a control system of the car is not activated; changing the
power supply, when said microcomputer receives a wake-up signal, to
the tuner into a normal supply state and activating a function for
monitoring an output signal of the tuner, and outputting a wake-up
request signal when the microcomputer decides that the received
.Iadd.wake-up .Iaddend.signal is .[.the.]. normal signal from the
remote controller, for waking up a predetermined device.
6. An electronic control method for a car having a tuner which
receives a signal from a remote controller and outputs a
.[.predetermined.]. signal to a microcomputer of an onboard
controller, comprising the steps of generating a wake-up signal;
deciding whether the .Iadd.generated .Iaddend.wake-up signal is
supplied from a particular device; executing a function, when said
.Iadd.generator .Iaddend.wake-up signal is supplied from the tuner,
for determining whether the .Iadd.generator .Iaddend.wake-up signal
is generated due to noise; and activating a predetermined device by
the microcomputer when it is determined that the generated wake-up
signal is not due to noise.
7. An electronic control method for a car having a tuner which
receives a signal from a remote controller, a microcomputer
controlling and activating a device provided in the car, and a
noise eliminating means for eliminating a high frequency noise
contained in an output signal of said tuner, implemented by a
software program executed via the microcomputer, comprising the
steps of: periodically sampling a signal inputted to the
microcomputer from said tuner; checking the signal inputted to the
microcomputer and again checking the signal inputted to the
microcomputer after a set time shorter than .[.the.]. .Iadd.a
.Iaddend.periodic sampling period and longer than a period of the
high frequency noise; and determining existence or absence of
.[.a.]. .Iadd.the high-frequency .Iaddend.noise on the basis of a
state of signal obtained by the preceding steps.
8. An electronic control apparatus for a car, comprising a
microcomputer configured to have low power consumption mode and to
receive a plurality of signals including a signal from a remote
controller at a wake-up terminal of said microcomputer, .Iadd.a
communications interface configured to receive a signal for
waking-up at least one selected control; device from said
microcomputer and to output a wake-up signal to the at least one
selected control device, .Iaddend. said microcomputer being further
configured to perform function checking as to whether, when a
signal is inputted at said wake-up terminal of said microcomputer,
the signal is from other than said remote controller, said
microcomputer also being further configured to perform function
checking as to whether a signal inputted at a digital input
terminal of said microcomputer is the correct signal from said
remote controller, only when the signal inputted at said wake-up
terminal was not the signal from other than said remote controller,
and as a result of the .Iadd.function .Iaddend.check, when the
signal has been decided as a correct signal from said .Iadd.remote
.Iaddend.controller, said microcomputer being still further
configured to output the signal for waking up a selected control
device at an output terminal of said microcomputer.
9. An electronic control apparatus for a car, comprising a
microcomputer configured to have low power consumption mode and to
receive a plurality of signals including a signal from a remote
controller at a wake-up terminal of said microcomputer, .Iadd.a
communications interface configured to receive a signal for
waking-up at least one selected control; device from said
microcomputer and to output a wake-up signal to the at least one
selected control device, .Iaddend. said microcomputer being further
configured to perform function checking as to whether when a signal
is inputted at said wake-up terminal of said microcomputer, the
signal is from other than said .Iadd.remote .Iaddend.controller,
and when the signal inputted at said wake-up terminal .[.was.].
.Iadd.is .Iaddend.the signal from .[.one except.]. .Iadd.other than
.Iaddend.said .Iadd.remote .Iaddend.controller, said microcomputer
being still further configured to output the signal for waking up
.[.a.]. .Iadd.said .Iaddend.selected control device at an output
terminal of said microcomputer.
10. An electronic control apparatus for a car, comprising a
microcomputer configured to have low power consumption mode and to
receive a plurality of signals including a signal from a remote
controller at a wake-up terminal of said microcomputer, .Iadd.and a
tuner configured to send said signals from said remote controller
to said wake-up terminal,.Iaddend. said microcomputer being further
configured to perform function checking as to whether, when a
signal is inputted at said wake-up terminal of said microcomputer,
the signal is or is not from .[.one except.]. said .Iadd.remote
.Iaddend.controller, said microcomputer being further configured to
perform function checking as to whether a signal inputted at a
digital input terminal of said microcomputer is or is not the
correct signal from said remote controller, only when the signal
inputted at said wake-up terminal .[.was.]. .Iadd.is .Iaddend.not
the signal from .[.once except.]. .Iadd.other that .Iaddend.said
controller, and said microcomputer being still further configured
to be restored to a low power consumption mode as a result of the
.[.check.]. .Iadd.function checking.Iaddend., when the signal has
been decided as not being the correct signal .[.form.]. .Iadd.from
.Iaddend.said .Iadd.remote .Iaddend.controller.
11. An electronic control for a car, comprising a microcomputer
configured to have a low power consumption mode .[.and.]. .Iadd.,
.Iaddend.a wake-up terminal and a digital signal terminal, a tuner
for receiving .[.the.]. .Iadd.a .Iaddend.signal from a remote
controller, and .Iadd.said computer being configured to switch
.Iaddend.a power supply .[.switchable.]. between said low power
consumption mode in which the power is intermittently supplied to
said tuner and a normal power supplying mode in which .[.the.].
power is continuously supplied, wherein said microcomputer is
further configured to receive a plurality of signals including a
signal from a remote controller at said wake-up terminal, said
microcomputer being further configured to perform function checking
as to whether, when a signal is inputted at the wake-up terminal of
said microcomputer, the signal is or is not from said tuner so
that, only when the signal inputted at said wake-up terminal is
determined to be the signal from said tuner, a function for
switching said power supply from said low power consumption mode to
said normal power supplying mode, and a function for checking as to
whether the signal from said tuner inputted at the digital input
terminal of said microcomputer is or is not normal are executable,
and said microcomputer being further configured to output .[.the.].
.Iadd.a .Iaddend.signal for waking up a selected control device at
.[.the.]. .Iadd.an .Iaddend.output terminal of said microcomputer
when the signal from said tuner inputted at the digital input
terminal of said microcomputer is determined to be normal.
12. An electronic control for a car, comprising a microcomputer
configured to have a low power consumption mode and a wake-up
terminal and a digital signal terminal, .[.a tuner for receiving
the signal from a remote controller, and.]. a power supply
switchable between said low power consumption mode in which the
power is intermittently supplied to .[.said.]. .Iadd.a
.Iaddend.tuner and a normal power supplying mode in which the power
is continuously supplied, said microcomputer being further
configured to receive a plurality of signals including .[.the.].
.Iadd.a .Iaddend.signal from a remote controller at said wake-up
terminal of said microcomputer, .Iadd.and .Iaddend. .Iadd.said
tuner being configured to receive the signal from remote controller
and to send said received signal to said wake-up terminal,.Iaddend.
said microcomputer being further configured to perform function
checking as to whether, when a signal is inputted at said wake-up
terminal of said microcomputer, the signal is or is not from said
tuner, and only when the signal inputted at said wake-up terminal
has been the signal from said tuner, a function for switching said
power supply from said low power consumption mode to said normal
power supplying mode, and a function for checking as to whether the
signal from said tuner inputted at the digital input terminal of
said microcomputer is or is not normal are executable, and said
microcomputer being still further configured to restore said power
supply to said low power consumption mode and to be shifted to said
low power consumption mode when the signal from said tuner inputted
at the digital input terminal of said microcomputer .[.has been.].
.Iadd.is .Iaddend.determined .[.as.]. .Iadd.to be .Iaddend.normal.
.Iadd.
13. An electronic control apparatus for a car, comprising: a key
insertion detecting unit for detecting the presence or absence of
the key inserted into a key switch, a door state detecting unit for
detecting an open or closed state of a door, a tuner connected to
an antenna for receiving the signal from a remote control unit, and
a control processing unit having; an input output interface
connected with said tuner, said key insertion detecting unit, and
said door state detecting unit, and a microprocessor for generating
an output signal to be transmitted to another unit on the basis of
a signal from said tuner, said key insertion detecting unit, and
said door state detecting unit through said input output interface,
said microprocessor being configured to be awakened for a short
time period upon reception by the antenna of a signal to determine
if the signal is or is not noise, and then wake-up another control
unit for the first time when the signal is not
noise..Iaddend..Iadd.
14. An electronic control apparatus for a car, comprising: a tuner
connected to an antenna for receiving the signal from a remote
control unit, a trunk opening actuator electrically coupled to an
actuator control unit for opening a trunk, and a control processing
unit having an input-output interface connected with said tuner and
said trunk opening actuator control unit, and a microprocessor for
generating an output signal applied to said trunk opening actuator
control unit on the basis of a signal from said tuner through said
input-output interface, wherein said control processing unit wakes
up said trunk opening actuator control unit upon receiving a signal
for said antenna to place said trunk opening actuator in a
controllable state and said microprocessor is configured to be
awakened for a short time period when said antenna receives the
signal in order to determine if the signal is or is not noise so
that the trunk opening actuator control unit can be wakened for the
first time if the signal is not noise..Iaddend..Iadd.
15. An electronic control apparatus for a car, comprising: a key
switch connected to a battery having an accessory terminal for
connecting said battery and a radio, an ignition terminal for
connecting said battery and an engine controlling unit, and a
starter switch for connecting said battery and a starter motor, a
tuner connected to an antenna for receiving the signal from a
remote control unit, control units directly applied with the
electric power from said battery without going through said key
switch, signal communication lines for transmitting a signal
between said control units, a communication unit provided on each
of said control units for effecting the transmission through said
signal transmission lines, and at least one of said control units
having the following, an input-output interface connected with said
tuner and further operatively coupled to said accessory terminal,
said ignition terminal and said starter switch, and a
microprocessor for generating a sleep/wake-up signal to be applied
to the at least one of said control units on the basis of the
signal from said tuner through said input-output interface, said
microprocessor being configured to be awakened for a short-time
period upon reception by the antenna of a signal to determine if
the signal is or is not noise, and then wake-up the at least one of
said control units for the first-time when the signal is not
noise..Iaddend.
Description
BACKGROUND OF THE INVENTION
The present invention relates to an electronic control system for
performing remote control over a car or vehicle with use of a radio
signal such as radio wave or infrared ray, called keyless entry and
more particularly, to an electronic control system for car remote
control which switches between its sleep and operational modes as
well as to a multiplex communication system employed for the
electronic control system.
As a system for controlling supply of power to this type of
electronic control system not having a remote control function, it
is known as disclosed in JP-A-63-71451 to stop a terminal clock
when power supply is unnecessary.
Also disclosed in JP-A-5-32142 is a system, when a
microcomputer-controlled system is put in its sleep mode, for also
causing a power supply for a watch dog timer to be automatically
turned OFF, thus realizing reduction in its current consumption.
Further, when it is desired to provide a remote control function to
the electronic controller, such a power control system as to follow
is considered.
An exemplary schematic arrangement of the power control system is
shown in FIG. 1 wherein reference numeral 50' denotes an electronic
controller. An antenna 54' receives a radio wave signal issued from
a transmitter T carried by a car driver and sends the radio wave
signal to a tuner 55'. The tuner 55' in turn, when receiving the
radio wave signal from the antenna 54', modulates the radio wave
signal into a digital signal and sends the digital signal to a
microprocessor unit (MPU) 56'. The MPU 56' judges the signal
received from the tuner 55' to control a trunk lid opener motor 60'
or the like. Numeral 58' denotes a low-frequency oscillation
circuit and numeral 59' denotes a high-frequency oscillation
circuit. The MPU operates with a high frequency clock received from
the high-frequency oscillation circuit 59' for the purpose of
performing high-speed calculating operation in a usual operational
mode; whereas, the MPU operates with a low frequency clock received
from the low-frequency oscillation circuit 58' for the purpose of
suppressing current consumption in a sleep mode. Control signals
62' and 63' act to stop the low- and high-frequency oscillation
circuits 58' and 59' respectively. In the illustrated example, even
in the sleep mode, the MPU operates at a low speed to monitor the
signal received from the tuner.
Such another system as shown in FIG. 2 is also considered. That is,
the system is arranged so that the output signal of the tuner 55'
is processed by a signal processing circuit 65 not by the MPU 56'
to be applied to the MPU as a wake-up signal and a control signal
for the MPU.
With the above prior art control unit for receiving the radio wave
signal and controlling power supply based on the received signal,
various types of electromagnetic waves are present in the air so
that, even when the tuner fails to receive the normal radio wave
signal, the tuner can issue an output signal. To avoid this, power
supply to the tuner is intermittently carried out from an
intermittent power supply 53' shown in FIG. 1 or 2 to reduce a
current to be consumed by the tuner. Further, for preventing noise
from waking up the control unit, the unit judges whether or not the
output signal of the tuner is normal on the basis of only first
part of the entire tuner output signal within a time duration
shorter than an intermittent time duration. When the control unit
judges that the tuner output signal is normal, the control unit
shifts the clock of the MPU to a higher frequency clock for usual
operation and also causes the intermittent power supply circuit to
supply power continuously in the example of FIG. 1. In the example
of FIG. 2, when a processing circuit 65 judges that the tuner
signal is normal, the MPU starts its operation to perform the usual
operation, and also causes the intermittent power supply 53' to
supply power continuously. Since the tuner signal having such a
waveform as shown in FIG. 3 is judged as not normal, the MPU will
not perform the usual operation. When the tuner signal is such a
pulse signal having a relatively wide pulse width as shown in FIG.
4 and first one (A) of pulses in the pulse signal is normally
input, on the other hand, the MPU performs the usual operation and
causes the intermittent power supply 53' to continuously supply
power to the tuner, thus reducing current consumption. In either
example, in order to judge whether or not the tuner signal is
normal, the oscillation circuits of the MPU are required in the
example of FIG. 1 while the oscillation circuit of the processing
circuit is required in the example of FIG. 2. In addition, even
when the pulses in the tuner signal are followed by a noise pulse
signal having a relatively small pulse width as in FIG. 4, that is,
even when it is later judged as unnecessary to start or wake up the
MPU, the MPU is already put in the usual control operation after
the once normal judgement. For this reason, the MPU can be put in
the sleep mode only after a re-sleeping procedure is carried out.
In this way, in the prior art, the low-frequency oscillation
circuit is operated even in the sleep mode so that, even when it is
unnecessary to wake up the system, the entire system is put in the
usual operation, thus disabling realization of sufficiently reduced
current consumption.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an electronic
control system and method which can sufficiently suppress current
consumption even in a high-noise application environment, and also
to provide a multiplex communication system using the electronic
control system or method.
In order to attain the above object, when a wake-up signal is
input, an MPU is first operated even when the wake-up signal is a
noise signal to merely judge whether or not the input signal is
normal, and only after the MPU reliably judges that the input
signal is a normal signal, the MPU is shifted to its usual
operation. Further, when judging that the input signal is the noise
signal prior to input of the full tuner signal, the MPU immediately
shifts to a sleep mode.
With such an arrangement as mentioned above, since the need for
provision of an oscillation circuit to a circuit for judgement of
whether to be a wake-up signal can be eliminated, current
consumption in the sleep mode can be suppressed. Further, even
after the MPU starts its operation, the MPU is not shifted to a
usual control operation until the MPU judges that the wake-up
signal is normal. Thus, as soon as the MPU judges that the input
signal is the noise signal, the MPU can be immediately shifted to
the sleep mode, whereby the time duration of operation of the MPU
can be minimized and current consumption can be suppressed even in
a high noise state.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of an arrangement of a prior art
electronic control system as a first example;
FIG. 2 is a block diagram of an arrangement of a prior art
electronic control system as a second example;
FIG. 3 shows waveforms of signals appearing in the prior art
example of FIG. 1 for explaining how to detect an output of a tuner
therein;
FIG. 4 shows waveforms of signals appearing in the prior art
example of FIG. 2 for explaining how to detect an output of a tuner
therein;
FIG. 5 is a block diagram of a central processing unit shown in
FIG. 6 showing a first embodiment of the present invention;
FIG. 6 is a block diagram of an arrangement of an electronic
control system in accordance with the first embodiment of the
present invention;
FIG. 7 is a block diagram of a terminal processor in the embodiment
of FIG. 6;
FIG. 8 shows waveforms of signals appearing in the embodiment of
FIG. 6 for explaining how to detect an output of a tuner
therein;
FIG. 9 shows waveforms of the signals appearing in the embodiment
of FIG. 6 for explaining how to detect the output of the tuner
therein;
FIG. 10 shows waveforms of the signals appearing in the embodiment
of FIG. 6 for explaining how to detect the output of the tuner
therein;
FIG. 11 shows waveforms of the signals appearing in the embodiment
of FIG. 6 for explaining how to detect the output of the tuner
therein.
FIG. 12 is a block diagram of an arrangement of a system for an
entire car;
FIG. 13 is a block diagram of the central processing unit as a
receiver;
FIGS. 14A, 14B and 14C show waveforms of parts of a signal for
explaining the operation of the electronic control system when
receiving a remote control signal;
FIG. 15 shows waveforms of the output of the tuner when the
electronic control system receives no remote control signal,
wherein
FIG. 15A is when noise is absent in the frequency band of the
signal received at an antenna and
FIG. 15B is when noise is present in the frequency band
thereof;
FIG. 16 shows waveforms of preamble and data parts A, B and B' in
the tuner output waveform, wherein
FIG. 16A is when the preamble part has no noise,
FIG. 16B is when the preamble part has noise,
FIG. 16C is when the data part has no noise and
FIG. 16D is when the data part has noise;
FIG. 17 is a flowchart for explaining how to avoid noise when
sample timing coincides with noise;
FIGS. 18A and 18B show waveforms of an input signal and an
extracted signal in a prior art and in the present invention
respectively;
FIG. 19 is a flowchart for explaining signal analyzing
operation;
FIG. 20 is a block diagram for explaining the operation of interior
of the central processing unit;
FIG. 21 shows waveforms of signals for explaining how to measure
pulse width;
FIG. 22 is a flowchart for explaining how to analyze a preamble
signal;
FIG. 23 is a waveform of the input signal for explaining how to
analyze the preamble signal;
FIG. 24 shows waveforms of an input signal at a terminal PI and a
free-run timer signal for comparison therebetween;
FIG. 25 is a flowchart for explaining the operation of the entire
system; and
FIG. 26 shows waveforms of converted high and low signals.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
There is shown a block diagram of an arrangement of an electronic
control system in accordance with a first embodiment of the present
invention in FIGS. 5 and 6, wherein FIG. 5 is a block diagram of
details of a central processing unit (CPU) 1 in FIG. 6. In FIGS. 5
and 6, terminal processors 3, 4 and 5 are connected to each other
by a multiplex communication line 7 so that input information on
switches connected to the respective terminal processors or output
information on lamps or motors connected thereto are transferred on
a multiplex communication basis to carry out entire control
thereover. In FIG. 5 showing the configuration of the central
processing unit 1, a battery 31 supplies power to the central
processing unit and also to respective devices of the entire
vehicle including the terminal processors 3, 4 and 5. A second
power supply circuit 32 switches between supply or non-supply of a
voltage of the battery to circuits positioned downstream thereof on
the basis of a signal received from a microprocessor unit (MPU) 11,
and a third power supply circuit 33 switches between supply or
non-supply of an output of a constant-voltage power supply circuit
30 to circuits positioned downstream thereof on the basis of a
signal received from the MPU 11. A switch unit 35 is made up of a
plurality of switches connected to the central processing unit to
supply power from the second or third power supply circuit to the
MPU through pull-up resistors 34a, 34b, 34c, 34d and 34e.
Similarly, a wake-up switch unit 36 is made up of a plurality of
switches connected to the central processing unit to supply power
from the battery or constant-voltage power supply circuit to the
MPU through the pull-up resistors 34a and 34c. More specifically,
switch signals of these switch units are connected to input ports
of the MPU to be read therein for control. The car is equipped with
a keyless entry radio system for remote control of the car, which
has a portable transmitter for emitting signals in the form of
electromagnetic wave or infrared ray such as a start signal of an
engine, an open/close signal of a trunk, or an open/close signal of
a power window, and which also has a receiver mounted on the car
for receiving the signal emitted from the transmitter. An antenna
37, which is attached to the receiver of the above radio system,
receives the aforementioned signal from the transmitter of the
radio system and applies it to a tuner 38 where the input signal is
demodulated an then sent to the MPU 11. A power supply circuit 39
for power supply to the tuner supplies power continuously for
intermittently to the tuner on the basis of a control signal
received from the MPU 11. An output signal of the switch unit 36
and an output signal of the tuner 38 are applied to a logical gate
40 which output is connected to the MPU 11 as a wake-up signal.
Although not illustrated in the drawing, these input signals are
previously subjected by a hardware filter circuit to removal of
high frequency components. An oscillation circuit 41 oscillates in
an operational mode of the car while stops its oscillating
operation in a sleep mode to reduce current consumption. A
communication IC 12 performs multiplex communication with another
terminal processor through the multiplex communication line 7. This
communication IC may be built in if necessary.
Shown in FIG. 7 is a structure of the terminal processor 3. The
terminal processors 4 and 5 have substantially the same structure
as the terminal processor 3. In the drawing, a communication IC 8
performs multiplex communication with the central processing unit
(CPU) 1 through the multiplex communication line 7 to send input
data from a device connected to the terminal processor to the
central processing unit 1 and to send data received from the
central processing unit 1 to an actuator 6 or the like connected to
the terminal processor. A communication control circuit 42 controls
the sending and receiving operation of the communication IC 8. An
oscillation control circuit 43 detects a sleep/wake-up signal from
the central processing unit and on the basis of the detected
signal, controls the oscillating operation of the oscillation
circuit 41 or stoppage thereof. Reference numeral 44 denotes an
input/output interface circuit. The terminal processors 4 and 5
have substantially the same structure as the terminal processor 3,
except that their input/output circuits are connected with switches
and actuators different from those of the terminal processor 3.
The MPU 11 of the central processing unit 1 receives input signals
from the switch units 35 and 36 and input signals from other
sensors and terminal processors, calculates control data on motors,
lamps, etc. connected to the central processing unit and on
actuators of the other terminal processors, and outputs the
calculated data thereto to perform entire control over the system.
With such an in-car system, when the engine is stopped and no
person rides in the car, the MPU stops oscillation of a clock
within the MPU, turns. OFF the second and third power supply
circuits 32 and 33, or stops oscillation of a clock within the
terminal processor, for the purpose of suppressing the power
consumption of the battery. The switches of the switch unit 36
include a door switch, a key insertion switch and an ignition
switch. Since these switches are used to shift the sleep mode to
the operational mode, it is necessary to detect the states of the
switches even when the system is in the sleep mode. To this end,
the switches are pulled up to the battery voltage or the voltage of
the constant-voltage power supply circuit 30. The switches of the
switch unit 35 include, for example, a wiper switch and a rear
defogger switch which states will not change in the sleep mode. As
for the rear defogger switch for example, this switch is operated
only when the ignition switch is in its ON state, so that the ON
state of the rear defogger switch means that the ignition switch is
already turned ON before the defogger switch in turned ON and thus
the system is in the operational mode. Thus, since it is
unnecessary in the sleep mode to detect the states of the switches,
the power to be supplied to the switches are set at the power of
the second or third power supply circuit 32 or 33 which is turned
OFF in the sleep mode. The tuner power supply circuit 39 is
required to operate even in the sleep mode, but the continuous
operation of the tuner power supply circuit at all times involves
great current consumption. To avoid this, the tuner power supply
circuit 39 is of an intermittent power supply type which supplies
power intermittently in the sleep mode. The intermittent power
supply circuit continuously supplies power during the operation of
the MPU. The signals of the wake-up switch unit 36 and the output
signal (tuner signal) of the tuner 38 for shifting the sleep mode
to the operational mode are applied to the MPU and concurrently
also to the logical gate 40. The logical gate 40 is connected at
its output to a wake-up request terminal of the MPU to output a
wake-up signal thereto so that, when receiving the wake-up signal,
the MPU initiates the oscillation circuit 41 to start the wake-up
operation.
Explanation will next be made as to the operation of the present
embodiment by referring to a flowchart of FIG. 11. When the entire
system is in the sleep mode, an input of a signal to the wake-up
request terminal causes the MPU to start the wake-up operation of
FIG. 11. More in detail, the system first judges at a step 101
whether or not the input signal to the wake-up request terminal is
the wake-up signal from the tuner on the basis of signals other
than the tuner signal applied to the terminals other than the
wake-up request terminal. When determining the wake-up request from
the non-tuner, the system transmits, at a step 105, the wake-up
request to the other control units (terminal processors 3, 4 and 5
in the present embodiment) through the multiplex communication line
7. The terminal processors 3, 4 and 5, when receiving the wake-up
signal, start their oscillating operation to start their main
operation. At a next step 106, the system turns ON the second and
third power supply circuits 32 and 33 to start power supply to the
entire circuits. After this operation, the system starts usual
control operation at a step 107. In this way, when the wake-up
signal is other than the tuner signal, the signal carries less
noise thereon and high frequency noise is eliminated by the
hardware filter circuit. Thus, when the system judges at the step
101 the signal applied to the wake-up request terminal, the system
can reliably determine it as a normal signal. Therefore, only once
judgement causes the system to shift to the usual control. When
judging at the step 101 that the input signal is from the tuner,
the system determines the input signal is the wake-up request from
the tuner and executes the operation of a step 102. Since the power
supply to the tuner is intermittently carried out in the sleep
mode, the input of the wake-up request signal causes the system to
output a change-over signal for continuous power supply. With it,
the system can judge whether or not the subsequent signal is
rightly input. The system judges at a step 103 whether the tuner
signal is normal or not until the system judges at a step 104 that
the tuner signal was fully input. The tuner signal is set in the
present embodiment to be constituted of 50 msec, or more of a
header signal having a period of 5 msec, and a duty cycle of 50%
followed by encoded ID code and command. When judging before the
full input of this tuner signal that the tuner signal is abnormal,
the system, at a step 108, performs sleep operation to cause the
MPU to stop its oscillating operation and enter again into the
sleep mode. Only when the tuner signal is fully input, the system
executes the operations of the steps 105 and 106 to initiate the
other control units and to turn ON the second and third power
supply circuits 32 and 33 to supply power to the entire circuits,
and then starts at the step 107 the usual control operation. In
this way, only when the tuner signal is fully normally input, the
entire system is shifted to the usual operational mode. Although
the entire system has been set to be shifted to the usual
operational mode only when the tuner signal is fully input in the
present embodiment, the shift to the usual control operation may be
carried out, e.g., when only the header signal is fully input or
when part of the header signal is input.
Explanation will then be made as to the effects of the present
embodiment. When power is intermittently supplied to the tuner,
noise is also input due to the presence of any type of
electromagnetic wave in the air. However, the noise is usually
shifted in frequency band and has a pulse width much narrower than
the normal signal. In addition, since the noise is eliminated by
the hardware filter circuit, the noise will not be included in the
wake-up request signal applied to the MPU. The noise, however, may
have a pulse width similar to that of the normal signal. In such a
case, the MPU wakes up. When the noise has such a waveform as shown
in FIG. 8, the input of the noise signal having a pulse width
similar to the normal signal causes the MPU to receive the wake-up
request signal (step 105). The MPU starts its oscillating operation
to execute the wake-up operation of FIG. 11. However, when the
system is monitoring the tuner signal in the wake-up operation and
immediately judges the signal is noise, this causes the MPU to be
immediately put in the sleep mode, so that the terminal processors
remain the sleep mode and the second power supply circuit also
remains in the OFF state. When the system is put in the sleep mode,
the power supply of the tuner power supply circuit to the tuner is
once turned OFF and later then tuner power supply circuit performs
its intermittent power supplying operation, which results in that
the time duration of power supply to the tuner becomes shorter than
that in the usual sleep mode and thus the current consumption of
the tuner is suppressed. Further, even when such a signal A similar
to the normal signal continues for some time as in FIG. 9, the
system is not shifted to the usual control operation until the
keyless signal is fully input, so that, as in FIG. 8, the terminal
processors keep the sleep mode and the second and third power
supply circuits 32 and 33 also remain in the OFF state.
Furthermore, as in the prior art, once the system is put in the
usual operational mode, it is necessary to put the terminal
processors in the sleep mode or to judge whether or not the
terminal processors have actually been put in the sleep mode. For
this reason, after shifted to the usual control mode, even when the
system judges that keyless signal is not normal and tries to shift
the current mode to the sleep mode, the entire system fails to
immediately shift to the sleep mode. In the present embodiment, on
the other hand, after the system judges that the keyless signal is
the normal signal, the system shifts the current mode to the usual
operational mode, which results in that, when the system judges
that the keyless signal is not the normal signal on the way, the
entire system can immediately shift the current mode to the sleep
mode. Accordingly, even when the keyless signal is not the normal
signal, the MPU put in the operational mode simultaneously causes
all controls to be put in the usual operational mode in the prior
art; whereas, only when the keyless signal is normal, the terminal
processors and the second power supply circuit are activated, thus
suppressing current consumption in the present embodiment. FIG. 10
shows the operational state of the input tuner signal when the
signal is normal.
In FIG. 10, more in detail, when a pulse signal having a pulse
width having a predetermined value or more is detected as a tuner
output and the pulse signal having the pulse width is continuously
received up to a time point P where all the keyless signal is
input; the system judges that the system is in the usual
operational mode and completes the wake-up operation. After the
time point P, the second and third power supply circuits 32 and 33
are operated to put the terminal processors in the operational
mode.
In accordance with the present invention, since the control system
is shifted to the usual operational mode only after the system
judges whether or not a signal received at the receiver is the
normal signal, even when the received signal contains much noise,
the current consumption can be suppressed.
Although the embodiment of the present invention has been explained
above in connection with FIGS. 5, 6 and 7, the present invention
will be explained in more detail in connection with a case where
the present invention is applied as a car electronic control
system. Referring to FIG. 12, there is shown a configuration of the
entire car electronic control system. In the drawing, a battery 31
supplies power to the car electronic control system. Reference
numeral 50 denotes an ignition key switch by which key position the
battery power is distributed to different locations. That is, when
the ignition key switch 50 is at a key position OFF, power supply
lines 90, 91 and 92 are disconnected from the battery power so that
no power is supplied; when the switch 50 is at an
accessory.(referred to merely as the ACC, hereinafter) key
position, the battery power is supplied only onto the power supply
line 90; when the switch 50 is at an ignition (referred to merely
as the IGN, hereinafter) key position, the battery power is
supplied to the power supply lines 90 and 91; and when the switch
50 is at a starter (referred to merely as the START, hereinafter)
key position, the battery power is supplied to the power supply
lines 91 and 92, in which case the power supply line 90 is
disconnected from the battery power. A radio set 52 is operated on
power supplied from the power supply line 90. A starter motor 51,
when the key switch is at the START position, is supplied with
power from the power supply line 92 and is driven to start an
engine. An engine control machine 53 (which will be referred merely
as the ECM 53, hereinafter), when receiving an intake air amount or
an engine rotational speed from a sensor (not shown), performs fuel
injection control or ignition control to drive a fuel injection
valve 56 (which will be referred to the injector 56, hereinafter),
a fuel pump 57 and so on. An anti-lock brake system (ABS)
controller 54 (which will be referred merely as the ABS controller
54, hereinafter) functions, even when an ABS motor 58 is controlled
to apply abrupt braking operation, to prevent wheels from being
locked. An automatic transmission (A/T) controller 55 (which will
be referred to merely as the A/T controller 55, hereinafter)
controls solenoids 59 and 60 and so on to automatically perform
gear shifting operation over a transmission according to the
driving state of the car. The ECM controller 53, ABS controller 54
and A/T controller 55 are designed to be operated when supplied
with power from the power supply line 91, i.e., when the ignition
key is at the IGN or START position.
Reference numeral 1 denotes a control processing unit (CPU) (which
will be referred to merely as the CPU 1, hereinafter), and numerals
3, 4, 5 and 69 denote terminal processors. The terminal processors
are interconnected to each other by means of a multiplex
communication line 7 so as to transfer input information on
switches or input information on actuators such as motors or lamps
connected to the associated terminal processors therebetween on a
multiplex communication basis to thereby realize general control.
The CPU 1 and terminal processors 3, 4, 5 and 69 are supplied with
power directly from the battery regardless of the position of the
ignition key switch. The CPU 1 includes a power supply circuit 67
made up of such constant-voltage power supply circuit 30, second
power supply circuit 32 and third power supply circuit 33 as shown
in FIG. 5, an I/O interface 66 having such a tuner 38 as shown in
FIG. 5, an MPU 11, and a communication IC 12. The operations of
these elements have been already explained in the foregoing
embodiment, and thus explanation thereof is omitted. Further, since
the structures and operations of the terminal processors 3, 4, 5
and 69 are the same as those in FIG. 7. Thus explanation will
centers, in particular, on constituent parts associated with the
keyless entry system. Numeral 68 denotes a transmitter for the
keyless entry system. An antenna 37 is used to receive a signal
transmitted from the transmitter 68. Although the antenna is
illustrated as provided outside of the CPU 1 in the present
embodiment, the antenna may be mounted inside of the CPU 1 as
necessary. Numeral 2 denotes a trunk opener motor for opening the
trunk, 61 a key insertion switch for detecting the presence or
absence of the key inserted in place, 62 a door switch for
detecting an open or closed state of the door, 63 a rear defogger
switch for controlling turning ON and OFF of the rear defogger, 64
a windshield wiper switch, 65 an illumination lamp for illuminating
the rear defogger switch 63, windshield wiper switch 64 and the
like. Such switches, lamp and motor as mentioned above are
connected to the CPU 1. Also connected to the CPU 1 are signals
ACC, IGN and START. The terminal processors 3, 4, 5 and 69 are
mounted to the doors of driver and assistant driver's seats and the
right- and left-side back seats and are also electrically connected
with door lock motors 71, 75, 79 and 83 for locking or unlocking
the associated doors and with power window motors 72, 76, 80 and 84
for opening or closing the door windows, respectively. Connected to
the terminal processor 3 of the driver seat are a door lock switch
73 for locking or unlocking the doors of all the seats, a power
window switch 74, other power window switches (not shown) of the
seats other than the driver seat, and a door lock detection switch
for detecting the locked or unlocked state of the doors. Connected
to the terminal processors 4, 5 and 69 of the assistant driver's
seat right- and left-side back seats are power window switches 77,
81 and 85.
Explanation will next be made as to the operation of the keyless
entry system. The `keyless entry system` as used herein refers to
such a system as to lock or unlock car doors or to open or close
the trunk room using a signal received from a radio device on a
remote control basis. The keyless entry system, because of being
operated on a remote control basis, is activated basically when no
person rides in the car. When the key insertion switch is in its
OFF state, i.e., when the key is not inserted, pushing of a lock
switch of the transmitter causes the transmitter to transmit a lock
signal (which will be detailed later). The signal is received at
the antenna 37 and sent to the CPU 1. When CPU 1 judges that the
received signal is the lock signal, the communication IC 12 in the
CPU 1 issues via the multiplex communication line 7 to the
communication ICs 8, 9, 10 and 70 of the terminal processors 3, 4,
5 and 69 such a signal as to drive the door lock motors 71, 75, 79
and 83 in such directions as to lock the associated doors
respectively. The communication ICs 8, 9, 10 and 70 of the terminal
processors 3, 4, 5 and 69, when receiving the aforementioned signal
from the communication IC 12, output lock signals to the door lock
motors 71, 75, 79 and 83 to lock the associated doors respectively.
Similarly, pushing of an unlock switch of the transmitter causes
the respective seat doors to be unlocked. Pushing of a trunk switch
of the transmitter causes the CPU 1 to output a signal to the trunk
opener motor connected to the CPU 1 per se to thereby open the
trunk.
Generally speaking, such operations are carried out in such a
manner that the transmitter user pushes the door lock switch on the
transmitter when he or she gets off and leaves the car, the user
pushes the transmitter door unlock switch while approaching the car
to ride in, or the user pushes the transmitter trunk switch while
approaching the car to put a shopping bag or bags in the trunk
after shopping. To this end, as mentioned above, the CPU 1 and
terminal processors 3, 4, 5 and 69 associated with the above are
directly connected to the battery so as to be always supplied with
power therefrom. Such a keyless signal, however, may be input
immediately after the user leaves the car or may be input after a
long period of time such as several hours or several days. In the
latter case, the continuous energization of the terminal processors
undesirably involves great current consumption. For the purpose of
suppressing the power consumption of the battery, in this case, the
terminal processors are put in the sleep mode. More specifically,
the terminal processors are designed to be put in the sleep mode
when the ignition key is in the OFF state or the key is not
inserted yet, the doors are closed, no keyless signal is input, and
all the loads are not activated at all. The operation of system in
the sleep mode and the operation thereof in the wake-up mode have
been already explained above and thus explanation thereof is
omitted.
Next, the keyless entry system will be explained in more detail.
Shown in FIG. 13 is a configuration of the entire system. A remote
control signal emitted from the remote controller or transmitter 68
is received at the antenna 37 and then sent to the tuner 38 built
in the CPU 1 as a master or base station. The signal guided into
the tuner 38 is converted to such a digital signal of high and low
levels as seen in FIG. 14B and then applied to the MPU 11 at its
terminal PI. The MPU 11 first decodes the remote control signal and
extracts a key code. After completing the extraction of the key
code, the MPU 11 then judges whether or not the key code is right.
When determining that the key code is right, the MPU 11 outputs a
signal to the communication IC 12 to drive the associated motor 6.
The communication IC 12 is connected to the plurality of line
control units (LCUs) or terminal processors as slave or branch
stations through the multiplex communication line 7 to communicate
therewith on a half duplex communication basis. The terminal
processors have unique addresses that are not overlapped with each
other, so that one of the terminal processors to communicate with
is selected based on their addresses. The signal for driving the
associated motor 6 is sent to the motor together with the address
of the associated terminal processor to drive the motor 6.
FIGS. 14A, 14B and 14C show a key code signal issued from the tuner
38. The signal is roughly divided into 3 pattern parts A, B and B',
and of course, the remote control signal per se issued from the
transmitter 68 is also divided into 3 parts.
More in detail, the part A corresponds to a preamble part of the
signal in which high and low levels are regularly repeated in the
signal waveform. The preamble part A is used for the MPU 11 to
judge whether the signal issued from the tuner 38 is a noise signal
or a remote control signal or to stabilize the operation of the
tuner circuit.
The part B is a data part which forms a pulse width modulation
(PWM) signal. The data part corresponds to a command part of the
remote control signal issued from the transmitter 68 (command
signal part). The part B is made up of a data head indicative of
the head of the data, 8 bits (from bit 7 to bit 0) of command
portion, and a parity bit.
The bit details of the command portion has such a waveform that `0`
and `1` are distinguished according to the pulse width, as shown in
the drawing. More specifically, when the pulse width is (1/3)T
(T:period), the pulse indicates `0`; whereas, when the pulse width
is (2/3)T, the pulse indicates `1`. The interpretation of a command
based on the distinguished `0` and `1` is known as "command signal
analysis". The part B' similar to the part B is used to carry out
again the command signal analysis in order to judge whether or not
the result of the signal analysis of the part B by the MPU 11 is
truly right. In other words, the part B' is used to judge whether
or not the result of the signal analysis is employed depending on
whether or not the signal analysis result of the part B coincides
with the that of the part B'. That is, this means that
two-successive signal collation is carried out. In this connection,
it is unnecessary that the parts B and B' have exactly the same
pattern. For example, an inversion of the signal of the part B may
correspond to the part B' for inverted 2 successive-signal
collation.
FIG. 15 shows waveforms of the output signal of the tuner 38 when
the CPU 1 fails to receive the remote control signal, wherein FIG.
15A is when noise is absent in the frequency band of a signal
received at the antenna 37. The preamble part of the output signal
of the tuner 38 has a continuous waveform always having a level
Lo.
FIG. 15B is when noise is present in the frequency band of the
received signal. That is, the preamble part of the signal has a
irregular pulsative waveform.
Differences between such regular right waveform, continuous
waveform and irregular fine pulsative waveform as mentioned above
are detected on the basis of differences in the pulse period of
`Hi` and `Lo` or in the pulse width to determine whether the remote
control radio signal was received or the remote control signal is a
noise signal.
First of all, explanation will be made as to the types of noise to
be removed. The noise shown in FIG. 15 is called usually white
noise, such as noise sound "Zaaa . . . " generated from an FM radio
receiver when the radio receiver is failing to receive broadcasting
electromagnetic waves. The receiver must distinguish the noise
signal from the remote control signal. The next type of noise is
high-frequency noise entrapped during the reception of the remote
control signal. This noise is featured generally by its great
energy and very narrow pulse width. In gasoline engines for use in
automobiles or cars, in particular, fuel ignition is entailed by
generation of ignition noise corresponding often to the above
high-frequency noise. Accordingly, the receiver must eliminate the
two types of noise, i.e., the white noise and high-frequency
one-shot-like noise.
FIGS. 16A to 16D shows waveforms of a key code signal when a remote
control signal is input in the absence or in the presence of noise.
The waveforms with "noise" in the drawing locally contain
high-frequency signal having narrow widths, that is, the original
signal is `polluted`. This noise signal corresponds to the latter
type of noise in the above explanation.
When it is desired to restore an input signal, in general, the
input signal is subjected to a sampling operation by a technique
based on the sampling theorem to be restored according to the
sampling period. However, if the noise position undesirably
coincides with the sampling timing, then this means that it is
impossible to execute the right sampling operation. To avoid this,
the receiver is reduced in its sensitivity not to pick up the
noise. This technique however, also makes it difficult to pick up
not only the noise but also the normal signal, so this is not a
good idea. In accordance with the present invention, after the
input signal is sampled with a sampling period, the input signal is
again confirmed after passage of a time sufficiently shorter than
the sampling period, whereby noise can be easily removed.
Shown in FIG. 17 is a flowchart for explaining how to avoid such a
case that the sampling timing coincides with noise position as
mentioned above and how to distinguish the remote control signal
from the white noise. A fixed-time interrupt operation 200 is
basically executed at intervals of a sampling period set based on
the sampling theorem to monitor a preamble part (part A) of the
output signal of the tuner to judge whether the input signal is the
remote control signal or the white noise.
More specifically, when the tuner output signal received at the
terminal PI of the MPU 11 has a "H" level in a step 201, the MPU 11
provides a predetermined delay time at a step 203. This delay time
is necessary to set a time corresponding to a pulse width of high
frequency noise to be removed. Subsequently at a step 204, the MPU
11 again examines the state of the terminal PI. This is when the
MPU 11 determined that the terminal PI has an "L" level state at
the step 204, that is, when the MPU 11 once recognized the terminal
state is "H" but the state was changed after the passage of the
time delay of the step 203. This means that the recognition of the
state at the terminal PI carried out at the step 201 or 204 is
invalid. That is, the signal picked up noise at the step 201 or
204. Thus, the MPU 11 returns to the step 201 to re-examine the
state of the terminal PI. This operation is repeated until the
state of the terminal PI before the delay time of the step 203
coincides with that after the delay time in a 2 successive
collation manner. Thus it will be seen from this operation that
noise having frequencies (or having pulse widths shorter than)
smaller than the delay time set at the step 203 is ignored. The
same holds true for steps 202 and 205 except that the logic of the
terminal PI is reversed to the steps 203 and 204. Explanation will
next be made as to how the signal is specifically changed by
referring to FIGS. 18A and 18B.
FIG. 18 shows a difference in the recognized (extracted) waveforms
of the input signal of the terminal PI based on the present
invention and a prior art when the input signal contains noise and
the sample timing coincides with the noise position. More
specifically, FIG. 18A is in the case of the prior art, in which,
since the MPU 11 judges the noise as a signal, the extracted
waveform collapses and thus the MPU 11 fails to perform correct
waveform recognition. On the other hand, FIG. 18B is in the case of
the present invention, in which the MPU 11 can perform correct
waveform recognition through the 2 successive collation of the
steps 201 to 205 in FIG. 17. In this way, in accordance with the
present invention, it will be appreciated that, even when noise is
entrained in the signal, the signal re-recognition is carried out
until a coincidence is found between the terminal states through
the 2 successive collation, which results in that correct waveform
recognition can be carried out.
Turning again to the explanation of the fixed-time interrupt
operation of FIG. 17, this interrupt operation basically monitors
the preamble part (part A) in the output signal of the tuner to
judge whether the signal is the remote control signal or white
noise signal, as already mentioned above. After the MPU 11 finishes
the operation when the sample timing coincides with the noise
position, the MPU 11 checks at a step 206 whether or not a counter
CT1 is 0. In the case of 0, the MPU 11 clears a flag HIOK at a step
207.
Subsequently, the MPU 11 increments the counter CT1 at a step 208
and clears a counter CT2 at a step 209. When the counter CT1
exceeds 4 at a step 210, the MPU 11 sets the flag HIOK at a step
211.
When the terminal PI is not in the "H" level state at the step 205,
the MPU 11 checks at a step 212 whether or not the counter CT2 is
0. If 0 then the MPU 11 clears a flag LOOK at a step 213.
Then the MPU 11 increments the counter CT2 at a step 214 and clears
the counter CT1 at a step 215. If the counter CT2 exceeds 4 at a
step 216, then the MPU 11 sets the flag LOOK at a step 217.
The MPU 11 judges at a step 218 whether or not the flags HIOK and
LOOK are both set. When the flags are set, the MPU 11 sets flag
RCOK at a step 219, that is, judges that the input signal is the
remote control signal. And at a step 220, the MPU 11 stops the
fixed-time interrupt operation.
As mentioned above, the noise/signal distinction is carried out
based on the pulse width or pulse period of the aforementioned part
A of the "Hi" and "Lo". In the present embodiment, when the pulse
width and period of the "Hi" and "Lo" are regularly repeated, the
MPU 11 determines that the input signal is the remote control
signal.
In this connection, the MPU 11 has a pulse width measuring function
of storing time moments at which rising edges in the input signal
the signal is applied to the terminal PI and at which a falling
edge in the input signal the signal is applied to the terminal PI.
Using this function, the MPU 11 usually can precisely measure the
pulse width or period. To this end, such a technique as shown in
FIG. 17 is employed. When much white noise is input, this causes
the operation based on the pulse width measuring function to be
repeated many times, which disadvantageously makes it impossible to
execute the other operations. The employment of the technique of
FIG. 17 is for the purpose of avoiding such a problem.
As has been explained above, in accordance with the present
invention, the separation between the white noise and remote
control signal is first carried out according to the procedure of
FIG. 17 and then the analysis of the remote control signal is
carried out using the pulse width measuring function of the MPU 11,
which advantageously results in that, even when the system is used
in a bad noisy environment, the analysis of the remote control
signal can be accurately realized. In this connection, it is
necessary that the fixed-time interval of the fixed-time interrupt
operation, the counting frequency of the counters, etc. be adjusted
according to the different waveforms of the remote control signal
and noise or to the different sampling methods so as to positively
realize the noise/signal distinction.
Next, explanation will be directed to the analyzing operation of
the remote control signal. FIG. 19 is a flowchart for explaining
how to recognize the key code in the remote control signal applied
to the terminal PI using the pulse width measuring function of the
MPU 11. This analyzing operation is automatically initiated by the
flag RCOK="1". This initiating method does not form an essential
part of the present invention and thus explanation thereof is
omitted.
Explanation will first be made as to the pulse width measuring
function of the MPU 11. FIG. 20 schematically shows the pulse width
measuring function. An edge detector 1010 selects catching of a
rising edge in the tuner output signal or catching of a falling
edge therein according to a command issued from an edge selector
1011 to always observe the signal applied to the terminal PI. The
command of the edge selector 1011 can be arbitrarily selected on a
software basis. A latch circuit 1012 holds a current value of a
free-fun timer 1013 on the basis of an edge detection signal
received from the edge detector 1010. The free-fun timer 1013
comprises a 16-bit counter which continually performs its
counting-up operation always in a constant time (1 .mu.sec in the
present embodiment), that is, which counts up from $0000 to $FFFF
and, when exceeding $FFFF, again starts its counting up operation
from $0000. In other words, when receiving the command from the
edge selector 1011 to catch the rising edge, the edge detector 1010
monitors the rising edge in the signal applied to the terminal PI
in such a manner that, when the edge detector 1010 inputs the
rising edge, the then value of the free-fun timer 1013 is held in
the latch circuit 1012.
Explanation will then be made as to hoe to measure the pulse width
with reference to FIG. 21 showing the input signal of the terminal
PI and the value of the free-fun timer 1013. In the drawing, the
free-run timer has a caught value of $F000 at a first rising edge
point A of the PI terminal input signal, has a caught value of
$8000 at a next falling edge point B and has a caught value of
$1000 at a next rising edge point C. Since time axis is set to be
directed from the left to the right in the drawing, a pulse width T
during which the input signal of the terminal PI has a level of
"Hi", corresponding to a subtraction of the count value at the
point A from the count value at the point B. Similarly, a pulse
width T' during which the terminal input signal has a level of
"Lo", corresponds to a subtraction of the count value at the point
B from the count value at the point C. Since a time taken for one
count of the free-run timer is 1 .mu.sec, the respective times T
and T' can be easily found by multiplying the count value by 1
.mu.sec. Accordingly, the time T is ($8000)-($F000)=$9000.
Similarly, the time T' is ($1000)-($8000)=$9000. These values are
represented in hexadecimal notation. Thus when these values are
converted to decimal values and then to time values, the time of
36.864 msec is obtained. It will be appreciated that the pulse
width or period can be freely measured by setting a falling or
rising edge in the signal of the terminal PI.
Turning again to the signal analyzing operation of FIG. 19,
explanation will be made as to how to receive the remote control
signal and as to how to remove noise when high-frequency noise is
included in the remote control signal during the reception of the
remote control signal. First, the general flow of the signal
analyzing operation will be explained. When the MPU 11 recognizes
through the fixed-time interrupt operation of FIG. 17 that the
remote control signal was input, the MPU 11 starts the signal
analyzing operation of FIG. 19. When the signal analysis is
completed at a step 301, the MPU 11 jumps to a step 306 to stop the
command signal analyzing operation and at a step 307, initiates and
completes the fixed-time interrupt operation, thus returning to a
remote control signal wait state.
When the signal analysis is not completed yet, the MPU 11 judges at
a step 302 whether or not the analysis of the part A (preamble
part) is completed. When the analysis is not completed yet, the MPU
11 goes to a step 400 to continuously execute the analysis of the
part A. The analysis of the part A at the step 400 is for the
purpose of reconfirming that the signal/noise distinction carried
out in FIG. 17 is truly correct.
When the detection of the part A is completed, the MPU 11 checks at
a step 303 whether or not the analysis of the part B (data part) is
completed. When the analysis of the part B is not completed yet,
the MPU 11 continuously executes the analysis of the part B at a
step 500. The key code analysis is actually carried out at this
step 500.
The MPU 11 checks at a step 304 a difference between the signal and
noise in the pulse width, pulse period and pattern or such an
abnormality as the time-over of data frame. In the presence of an
abnormality, the MPU 11 erases the analyzed command at a step 305.
At the next step 306, the MPU 11 stops its own command signal
analyzing operation, and initiates and completes at the step 307
the fixed-time interrupt operation.
Explanation will next be made as to the preamble analyzing
operation of the step 400. In this operation, the part A of the
remote control signal is analyzed as already mentioned above. The
part A has such a regular correct square waveform having a duty
cycle of 50% as shown in FIG. 14. In the present embodiment, only
when such a signal part continues for a predetermined time TM1, the
MPU 11 judges that the signal part corresponds to the head of the
remote control signal.
Shown in FIG. 22 is a flowchart for explaining the preamble
analyzing operation. The MPU 11 first clears the timer TMR at a
step 401. This timer, which performs its counting-up operation
based on a fixed-time interrupt operation different from the
fixed-time interrupt operation of FIG. 17, eventually measures an
edge interval of the signal at the terminal PI. The signal
analyzing operation of FIG. 19 is initiated only in response to the
presence of the input signal. Thus, when the input signal becomes
null, the signal analyzing operation is not initiated and remains
without being initiated indefinitely. To avoid this, this timer is
used to cause the MPU 11 to detect the absence of the input signal
applied to the terminal PI (i.e., the absence of the remote control
signal), to interrupt the signal analyzing operation and to return
the current operation to the initial state. Thus, even when the
remote control signal breaks off after starting of the remote
control signal analyzing operation, the MPU 11 can recognize its
abnormality and retry it from the beginning, thus realizing the
execution of the signal analysis without waste time.
At a step 402, the MPU 11 judges whether the input edge is rising
one or falling one. When the input edge is rising one, the MPU 11
waits for a certain time at a step 403. After this, the MPU 11
confirms the level of the input signal at the terminal PI at a step
404. When the input signal has a level of "L", that is, when the
signal does not rise though the MPU 11 catches the rising edge in
the input signal of the terminal PI, the MPU 11 can regard the
caught signal as a high frequency noise signal. At this stage, the
MPU 11 interrupts the operation and finishes the operation of the
step 400 to get ready for a new input signal. Similarly, when the
MPU 11 judges at the step 402 that the input edge is falling one,
the MPU 11 goes to a step 405 to provide a delay time and then goes
to a step 406 to confirm the level of the input signal. When the
input signal has a level of "H" though the MPU 11 catches the
falling edge, the MPU 11 judges the input signal is a high
frequency noise signal and finishes the operation of the step
400.
The operations as far as this stage will be explained by referring
to FIG. 23. The drawing shows a waveform of the remote control
signal applied to the terminal PI, an enlarged waveform of the
remote control signal having high frequency noise (such as car
ignition noise or the like) carried thereon, and the effects of the
respective steps 405 and 406. In general, high frequency noise is
characterized by having a narrow pulsative width. Utilizing this
feature, the present invention is designed to eliminate the noise.
It is assumed in FIG. 23 that, when the MPU 11 tried to detect the
next falling edge to measure its pulse width following the
detection of a rising edge in the remote control signal during
analysis of the preamble signal, noise was input to the remote
control signal.
When the falling edge of the signal is applied to the terminal PI
and the MPU 11 initiates the signal analyzing operation of FIG. 19,
the MPU 11 executes the preamble analysis operation of the step
400. Because of the falling edge, the MPU 11 first provides the
delay time at the step 405 to wait for a certain time. Since this
delay time is data to vary depending on the pulse width of noise to
be eliminated, its exact value cannot be determined
unconditionally. After this, the MPU 11 checks the level of the
signal at the terminal PI at the step 406. Now that the initiation
condition of the step 400 was satisfied, that is, that the MPU 11
caught the falling edge, the signal naturally should have a level
of "L". When the signal has a level of "H" in spite of the above
fact, however, it is considered that pulse shorter than the delay
time of the step 405 was input. Since the pattern of the remote
control signal applied to the terminal PI is naturally known on the
receiver side, the MPU 11 can readily judge that such a short
signal is an abnormal signal (noise). Accordingly, even when high
frequency noise is input a plurality of times, the MPU 11 can judge
that these are all noise. In this connection, when noise is present
in the vicinity of the edge of the correct remote control signal,
this noise might be judged as a normal signal. However, since an
error caused by this noise takes place for a time corresponding to
the above delay time, this noise continues for a time is too small
to be significant. In the present embodiment, for example, the
normal remote control signal has a pulse width of about 2 msec,
whereas the sustained time (delay time) of noise to be removed is
about 10 .mu.sec.
Since the present invention can completely separate the high
frequency noise from the normal remote control signal through such
operations as mentioned above, the invention can provide a signal
analysis technique which is immune to noise environment.
Turning again to FIG. 22, explanation will be continued. When first
detecting a rising edge, the MPU 11 passes through the steps 403
and 404 and goes to a step 407 to measure a time TP2. At the very
beginning, there is no data at a time SVFRCT at which the previous
rising edge was input. Thus, the value of a pulse period TP2 is
unreliable so that the MPU 11 finds NO at a step 408, executes the
operation of a step 410 to find a relation of TP2OK="0". The flag
TP2OK is used to judge whether or not the pulse period TP2 is
normal. At a next step 411, the MPU 11 causes the edge selector
1011 in FIG. 20 to be switched so as to select a falling edge. At a
next step 412, the MPU 11 stores the time of the rising edge in the
time SVFRCT. Thus it will be understood that the data of the time
SVFRCT indicates a time at which the rising edge of the signal
applied to the terminal PI was input. At a step 418, the MPU 11
judges whether or not the flags TP1OK and TP2OK are both "1". In
this case, since the both flags are not both "1" (NO), the MPU 11
goes to a step 420 to clear a timer TM1. The timer TM1 starts and
counts up like the timer TMR at the step 401 when the flags TP1OK
and TP2OK are both "1". This timer is used to judge the completion
of detection of the preamble only when the preamble was
continuously detected for a certain time. This timer also
prescribes a time after the completion of the preamble detection
until the next key code analyzing operation starts. In the present
embodiment, for the purpose of recognizing the remote control
signal more reliably, there are provided the timer TMR for
detecting a break or interruption in the remote control signal, the
timer TM1 for prescribing a limit time from the detection-of the
preamble signal to the start of the key code analysis, and a timer
TM2 for prescribing a limit time from the start of the key code
analysis to the completion of the analysis. Though not described in
the present embodiment, when the timer TM1 expires its preset time,
the MPU 11 issues a sign signal indicative of the completion of the
preamble part analysis at the step 302 to give a clue to the next
step 303, or detects an abnormality to initialize the signal
analyzing operation to quickly get ready for a next input of the
remote control signal.
The storage of data in the time SVFRCT means to have determined a
reference time. Further, since the terminal PI is set so as to
catch the next falling edge, the terminal gets ready for the next
falling edge.
An input of the falling edge causes the MPU 11 to pass through the
step 402, 405 and 406 and to go to a step 413 to measure a time
TP1. Symbol ICR denotes the value of the free-run timer caught by
the latch circuit 1012 in FIG. 20. Accordingly, when the time
SVFRCT is subtracted from the value ICR, a time necessary from the
rising edge to the falling edge is found. It will be noted that the
found necessary time corresponds to the pulse width of the "Hi"
duration in the signal applied to the terminal PI. It will also be
easily appreciated that the aforementioned pulse period TP2
corresponds to a time duration from the rising edge to the rising
edge, i.e., the pulse period. Further, TP1L, TP1H and TP2L, TP2H
are tolerance limit ranges for judgement of the input signal as a
normal signal having the respective times TP1 and TP2. As will be
seen, when the times TP1 and TP2 are within their tolerance ranges,
the flags TP1OK and TP2OK are set; whereas, when the TP1 and TP2
are out of their tolerance ranges, these flags are cleared.
Shown in FIG. 24 is a relationship among these data and limit
values. It will be noted from the drawing that the time TP1
indicates a pulse width, TP1H and TP1L are tolerance ranges
thereof, the time TP2 indicates another pulse width, TP2H and TP2L
are tolerance ranges thereof, the TP1 corresponds to a difference
between points B and A of the free-run timer, the TP2 corresponds
to a difference between points C and A, and measurement is
sequentially repeated.
It will be appreciated from the foregoing explanation that the
preamble part analyzing/detecting operation of FIG. 22 can be
immune to noise environment.
Explanation will next be made as to the key code analyzing
operation of the step 500 in FIG. 19. At a first step 501, the MPU
11 clears the timers TMR and TM1 and executes the timer TM2 start
judging operation. The timer TMR similar to that used in the step
401 in FIG. 22 is used for the same purpose and thus explanation
thereof is omitted. At a step 502, the MPU 11 performs
high-frequency noise removing operation. This noise removing
operation is the same as the contents already explained in FIGS. 22
and 23 and thus explanation thereof is omitted. At a next step 503,
the MPU 11 confirms the presence or absence of an input edge, that
is, judges whether the input edge is rising one or falling one. In
the case of the falling edge, the pulse width measurement is
carried out as mentioned in FIG. 22. In the case of key code, a
means for distinguishing between data "0" and "1" depending on the
magnitude of the pulse width is added. Which has been already
explained in connection with FIG. 14. In the operations of from the
step 507 to a step 511, the MPU 11 judges the data "0" or "1"
depending on whether the falling edge position is within a pulse
width or range TD1 or TD2. When the falling edge is out of the
range, the MPU 11 immediately stops the operation. This means that
signals outside of the judgement ranges are ignored, or to the
contrary, that any data is judged as normal so long as the data is
within the judgement ranges. Assume now that a remote control
signal similar in pattern to that in the present embodiment was
input. Then this signal can be easily judged as correct data
disadvantageously. This disadvantage is eliminated by repetitively
inputting its data part a plurality of times. In other words, the
frame of the input data part is examined on a multiple successive
collation basis to judge whether to be genuine (parts B and B' in
FIG. 14).
In this way, in accordance with the present invention, since a
signal similar to the remote control signal is positively input,
this helps improve the reception sensitivity; while, since the
input data is examined on a multiple successive collation, this
helps secure the data reliability, thus realizing provision of a
noise-immune receiver.
When judging at the step 503 the input edge is rising one, the MPU
11 judges at steps 504 and 506 whether or not the rising edge
position is normal. When the rising edge position is normal, this
results in that TD3OK="1", whereas, when the rising edge position
is abnormal, this results in that TD3OK="0". When the MPU 11 judges
at a step 512 whether or not the flag TD3OK and pulse width are
both normal. If the both are abnormal, then the MPU 11 goes to a
step 518 to perform initializing operation and to retry the signal
analyzing operation of FIG. 19 from the beginning. When determining
at the step 512 that the both are normal, the MPU 11 proceeds to a
step 513 to store the judged data and then to a step 514 to clear
the timer TM1 and to start the timer TM2. The timer TM1 is cleared
at this time point, since the timer TM1 is started at the step 419
in FIG. 22 and prescribes the sustained preamble time and a time
until the key code recognition is started. The timer TM2 is started
only once when the key code analyzing operation starts, and
prescribes the limit time from the start of the key code analyzing
operation to the completion of extraction of the key code. This
timer also counts up through a fixed-time interrupt operation
different from the fixed-time interrupt operation as in the
aforementioned timers, detects an abnormality when the key code
detection becomes too long or when the signal is interrupted in
order to immediately get ready for reentry of the execution from
the beginning. When the time-limited timers are built in at various
locations as in the present invention, even generation of an
abnormality enables the invention can perform signal analyzing
operation without waste or idle time.
At a step 515, the MPU 11 judges the completion or non-completion
of input of all the data. When determining the completion of the
full data input, the MPU 11 goes to a step 516 to perform data
collation. That is, the MPU 11 judges on a multiple successive
collation basis whether or not the data parts inputted a plurality
of times are the same. When this judgement result is OK, the MPU 11
proceeds to a step 518; whereas, when the result is NO, the MPU 11
goes to the step 519 to initialize the operation and to reentry the
operation from the beginning.
Shown in FIG. 26 is a relationship among data "0" and "1", data
values on pulse periods, and tolerance ranges thereof with respect
to the input signal applied to the terminal PI. In the drawing, the
signals are illustrated by solid lines when the data "0" is input,
while, the signals are illustrated by broken lines when the data
"1" is input. FIG. 26 basically has the same contents as FIG.
24.
As has been explained in the foregoing, in accordance with the
present invention, since a signal can be separated from noise while
preventing the receiver sensitivity from being decreased, there can
be provided a remote-controlled system which can exhibit its
performance ability fully even in severe noise environment.
* * * * *