U.S. patent application number 16/843739 was filed with the patent office on 2020-10-15 for method for debouncing an electrical input signal, and debouncing module.
This patent application is currently assigned to ZF Automotive Germany GmbH. The applicant listed for this patent is ZF Automotive Germany GmbH. Invention is credited to Tobias Oesterwind.
Application Number | 20200328735 16/843739 |
Document ID | / |
Family ID | 1000004811404 |
Filed Date | 2020-10-15 |
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United States Patent
Application |
20200328735 |
Kind Code |
A1 |
Oesterwind; Tobias |
October 15, 2020 |
METHOD FOR DEBOUNCING AN ELECTRICAL INPUT SIGNAL, AND DEBOUNCING
MODULE
Abstract
A method for debouncing an electrical input signal (x.sub.in)
includes following steps: (1) an input signal (x.sub.in) is
received and a present value of the input signal (x.sub.in) is
ascertained; (2) ascertaining whether the present value of the
input signal (x.sub.in) is above or below at least one predefined
limit value (x.sub.G); (3) producing a debounce status variable
(x.sub.E) having a defined initial value; (4) altering the value of
the debounce status variable (x.sub.E) on the basis of at least
whether the value of the input signal (x.sub.in) is above or below
the at least one limit value (x.sub.G), (5) generating an output
signal (x.sub.out) on the basis of whether the value of the
debounce status variable (x.sub.E) corresponds to the minimum value
(W.sub.min), to the maximum value (W.sub.max) or to a value between
the minimum value (W.sub.min) and the maximum value
(W.sub.max).
Inventors: |
Oesterwind; Tobias;
(Duesseldorf, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ZF Automotive Germany GmbH |
Alfdorf |
|
DE |
|
|
Assignee: |
ZF Automotive Germany GmbH
Alfdorf
DE
|
Family ID: |
1000004811404 |
Appl. No.: |
16/843739 |
Filed: |
April 8, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H03K 5/1254
20130101 |
International
Class: |
H03K 5/1254 20060101
H03K005/1254 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 11, 2019 |
DE |
102019109653.7 |
Claims
1. A method for debouncing an electrical input signal (x.sub.in),
having the following steps: receiving the input signal (x.sub.in),
ascertaining a present value of the input signal (x.sub.in),
ascertaining whether the present value of the input signal
(x.sub.in) is above or below at least one predefined limit value
(x.sub.G); producing a debounce status variable (x.sub.E) having a
defined initial value; altering the value of the debounce status
variable (x.sub.E) on the basis of at least whether the value of
the input signal (x.sub.in) is above or below the at least one
limit value (x.sub.G), wherein the value of the debounce status
variable (x.sub.E) is alterable between a minimum value (W.sub.min)
and a maximum value (W.sub.max), and generating an output signal
(x.sub.out) on the basis of whether the value of the debounce
status variable (x.sub.E) corresponds to the minimum value
(W.sub.min), to the maximum value (W.sub.max) or to a value between
the minimum value (W.sub.min) and the maximum value
(W.sub.max).
2. The method according to claim 1, wherein the output signal
(x.sub.out) is a binary signal.
3. The method according to claim 1, wherein the value of the output
signal (x.sub.out) is altered if the value of the debounce status
variable (x.sub.E) reaches the minimum value (W.sub.min) or the
maximum value (W.sub.max).
4. The method according to claim 2, wherein the present value of
the output signal (x.sub.out) is maintained for as long as the
value of the debounce status variable (x.sub.E) is between the
minimum value (W.sub.min) and the maximum value (W.sub.max).
5. The method according claim 3, wherein the value of the debounce
status variable (x.sub.E) is raised with a predefined first
gradient if the ascertained present value of the input signal
(x.sub.in) is above the at least one limit value (x.sub.G;
x.sub.G1), and/or the value of the debounce status variable
(x.sub.E) is lowered with a predefined second gradient if the
ascertained present value of the input signal (x.sub.in) is below
the at least one limit value (x.sub.G; x.sub.G2).
6. The method according to claim 5, wherein the first gradient
and/or the second gradient are or is ascertained on the basis of
how far the present value of the input signal (x.sub.in) is above
or below the at least one limit value (x.sub.G; x.sub.G1,
x.sub.G2).
7. The method according to claim 6, wherein the magnitude of the
value of the first gradient and/or of the second gradient is
greater the further away the present value of the input signal
(x.sub.in) is from the at least one limit value x.sub.G; x.sub.G1,
x.sub.G2).
8. The method according to claim 6, wherein the first gradient
and/or the second gradient is ascertained on the basis of a
characteristic curve, wherein the characteristic curve assigns a
gradient to the value of the input signal (x.sub.in).
9. The method according to claim 7, wherein there is provision for
at least one primary and one secondary first gradient and also at
least one predetermined positive limit value (x.sub.P) above the at
least one limit value (x.sub.G; x.sub.G1), wherein the value of the
debounce status variable (x.sub.E) is raised with the primary first
gradient if the ascertained present value of the input signal
(x.sub.in) is below the at least one positive limit value (x.sub.P)
but above the at least one limit value (x.sub.G; x.sub.G1) and
wherein the value of the debounce status variable (x.sub.E) is
raised with the secondary first gradient if the ascertained present
value of the input signal is above the at least one positive limit
value (x.sub.P); and/or in that there is provision for at least one
primary and one secondary second gradient and also at least one
predetermined negative limit value (x.sub.N) below the at least one
limit value (x.sub.G; x.sub.G2), wherein the value of the debounce
status variable (x.sub.E) is lowered with the primary second
gradient if the ascertained present value of the input signal
(x.sub.in) is above the at least one negative limit value (x.sub.N)
but below the at least one limit value (x.sub.G; x.sub.G2) and
wherein the value of the debounce status variable (x.sub.E) is
lowered with the secondary second gradient if the ascertained
present value of the input signal (x.sub.in) is below the at least
one negative limit value (x.sub.N).
10. The method according to claim 8, wherein there is provision for
a first predefined limit value (x.sub.G1) and a second predefined
limit value (x.sub.G2), wherein the value of the debounce status
variable (x.sub.E) is maintained for as long as the present value
of the input signal is between the two limit values (x.sub.G1,
x.sub.G2).
11. The method according to claim 10, wherein the value of the
debounce status variable (x.sub.E) is raised with the first
gradient if the ascertained present value of the input signal
(x.sub.in) is above the greater of the two limit values (x.sub.G1,
x.sub.G2) and/or the value of the debounce status variable
(x.sub.E) is lowered with the second gradient if the ascertained
present value of the input signal (x.sub.E) is below the smaller of
the two limit values (x.sub.G1, x.sub.G2).
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to German Patent
Application No. 102019109653.7, filed Apr. 11, 2019, the disclosure
of which is incorporated herein by reference in its entirety.
TECHNICAL FIELD
[0002] The invention relates to a method for debouncing an
electrical input signal and to a debouncing module.
BACKGROUND
[0003] Electrical signals in general and electrical signals from
sensors specifically can be described as a superimposition
comprising an ideal, interference-free signal and additional
interference
[0004] Said interference typically has a randomly distributed
component that is described as additive white Gaussian noise, for
example. As a result, the electrical signal has high-frequency
interference superimposed on it. The interference thus alters the
electrical signal, so that it differs from the ideal signal.
[0005] In many different situations, it is necessary to ascertain
whether the interference-free electrical signal is above or below a
predefined limit value. This often involves a binary output signal
being produced, the value of which is dependent on whether the
interference-free electrical signal is above or below a predefined
limit value.
[0006] Particularly in immediate surroundings of the limit value,
however, the interference described above results in the electrical
signal changing between the range above the limit value and the
range below the limit value at a very high frequency and hence in
what is known as bouncing occurring. It is therefore difficult to
decide whether the interference-free signal is above or below the
limit value or exceeds the limit value. Accordingly, the value of
the output signal produced in this limit range would jump to and
from between the two possible values at a high frequency (this
phenomenon is also referred to as "toggling").
[0007] The prior art reveals methods in which the electrical signal
is debounced by virtue of the value of the output signal being
changed only when the electrical signal is continuously above or
below the limit value for a predefined period. This approach can
lead to long delays, however, particularly in the case of a very
noisy signal, since the electrical signal repeatedly exceeds the
limit value, if only briefly.
SUMMARY
[0008] It is thus an object of the invention to provide a method
for debouncing an electrical input signal and a debouncing module
that allow even very noisy electrical signals to be debounced with
short delay times.
[0009] The object is achieved according to the invention by a
method for debouncing an electrical input signal, having the
following steps:
[0010] receiving the input signal;
[0011] ascertaining a present value of the input signal;
[0012] ascertaining whether the present value of the input signal
is above or below at least one predefined limit value;
[0013] producing a debounce status variable having a defined
initial value;
[0014] altering the value of the debounce status variable on the
basis of at least whether the value of the input signal is above or
below the at least one limit value, wherein the value of the
debounce status variable is alterable between a minimum value and a
maximum value; and
[0015] generating an output signal on the basis of whether the
value of the debounce status variable corresponds to the minimum
value, to the maximum value or to a value between the minimum value
and the maximum value.
[0016] The method according to the invention is based on the basic
idea of introducing an additional variable, namely the debounce
status variable, which is a measure of how likely it is that the
actual value of the electrical input signal is above or below the
limit value.
[0017] In contrast to the prior art, a timer is thus not reset each
time the electrical input signal exceeds the limit value, but
rather the value of the debounce status variable is continually
adjusted.
[0018] For a change in the value of the output signal, it is
therefore sufficient if the present value of the input signal is
one side of the limit value for long enough on the whole over a
certain period, It is thus no longer necessary for the present
value of the input signal to be continuously one side of the limit
value over the certain period.
[0019] The influence of brief, that is to say high-frequency,
fluctuations is reduced thereby and the electrical signal is
debounced with shorter delays.
[0020] Preferably, the initial value of the debounce status
variable is determined on the basis of the present value of the
input signal. To be more precise, the initial value is set equal to
the minimum value if the present value of the input signal is less
than the limit value, and is set equal to the maximum value if the
present value of the input signal is greater than the limit value.
Alternatively, the initial value of the debounce status variable
may also be prescribed, however, for example as the minimum value
or as the maximum value.
[0021] By way of example, the minimum value is equal to zero and
the maximum value is equal to one. Naturally, however, any other
isolated range can also be used.
[0022] In particular, the electrical input signal is a measurement
signal from a sensor or an already further-processed measurement
signal from a sensor. By way of example, the electrical input
signal is the signal from a torque sensor, from an angle position
sensor, from a temperature sensor, from a voltage sensor, from a
current sensor and/or from a force sensor. The applicable sensor
from which the input signal originates may be part of a steering
system for a motor vehicle.
[0023] In accordance with one configuration of the invention, the
output signal is a binary signal. The output signal thus has two
possible values corresponding to the interpretations "electrical
input signal above the limit value" and "electrical input signal
below the limit value".
[0024] Preferably, the value of the output signal is altered if the
value of the debounce status variable reaches the minimum value or
the maximum value. In this case, the minimum value corresponds to
the interpretation that the electrical input signal is below the
limit value, which is why the reaching of the minimum value is
followed by an output signal being output that corresponds to this
state. Analogously, the maximum value corresponds to the
interpretation that the electrical input signal is above the limit
value, which is why the reaching of the maximum value is followed
by an output signal being output that corresponds to this
state.
[0025] A further aspect of the invention provides for the present
value of the output signal to be maintained for as long as the
value of the debounce status variable is between the minimum value
and the maximum value. Expressed another way, the output signal is
thus altered only if the debounce status variable reaches one of
its two extreme values, that is to say the minimum value or the
maximum value. This reliably prevents the value of the output
signal from changing at a high frequency, in particular from
jumping to and fro at a high frequency.
[0026] In accordance with a further configuration of the invention,
the value of the debounce status variable is raised with a
predefined first gradient if the ascertained present value of the
input signal is above the at least one limit value, and/or the
value of the debounce status variable is lowered with a predefined
second gradient if the ascertained present value of the input
signal is below the at least one limit value. The first and second
gradients may be equal to or different from one another.
[0027] At this juncture and below, the term "predefined gradient"
means that the first gradient and/or the second gradient are at
least stipulated, that is to say constant, or are ascertained by
the signal processing unit on the basis of stipulated criteria.
[0028] Preferably, the first gradient and/or the second gradient
are or is ascertained on the basis of how far the present value of
the input signal is above or below the at least one limit value. As
a result, there is more weight to values of the input signal that
are very far away from the limit value and thus give a greater
indication that the input signal is on a specific side of the limit
value.
[0029] More preferably, the magnitude of the value of the first
gradient and/or of the second gradient is greater the further away
the present value of the input signal is from the at least one
limit value. As a result, the value of the debounce status variable
is altered more quickly if the present value of the input signal is
further away from the limit value, as a result of which the delays
when debouncing the input signal are reduced further.
[0030] In accordance with a further configuration of the invention,
the first gradient and/or the second gradient is ascertained on the
basis of a characteristic curve, wherein the characteristic curve
assigns a gradient to the value of the input signal. Expressed
another way, the gradient of the debounce status variable is then
thus a function of the distance of the present value of the input
signal from the limit value, preferably a monotonously rising
function, in particular a stringently monotonously rising function.
The function in this case may be continuous or discontinuous. By
way of example, the characteristic curve can have staircase-shaped
sudden changes.
[0031] A further aspect of the invention provides for there to be
provision for at least one primary and one secondary first gradient
and also at least one predetermined positive limit value above the
at least one limit value, wherein the value of the debounce status
variable is raised with the primary first gradient if the
ascertained present value of the input signal is below the at least
one positive limit value but above the at least one limit value and
wherein the value of the debounce status variable is raised for the
secondary first gradient if the ascertained present value of the
input signal is above the at least one positive limit value, and/or
in that there is provision for at least one primary and one
secondary second gradient and also at least one predetermined
negative limit value below the at least one limit value, wherein
the value of the debounce status variable is lowered with the
primary second gradient if the ascertained present value of the
input signal is above the at least one negative limit value but
below the at least one limit value and wherein the value of the
debounce status variable is lowered with the secondary second
gradient if the ascertained present value of the input signal is
below the at least one negative limit value.
[0032] Expressed another way, the at least one limit value, the
positive limit value and the negative limit value define multiple
bands that each correspond to a predefined gradient of the debounce
status variable. In particular, the gradient is constant within the
individual bands but different between the individual bands.
[0033] There may be provision for a second predefined limit value,
wherein the value of the debounce status variable is maintained for
as long as the present value of the input signal is between the two
limit values. The two limit values thus bound a dead band as it
were, within which the value of the debounce status variable does
not change. As such, a dead band can be implemented in a simple
manner.
[0034] In particular, the value of the debounce status variable is
raised with the first gradient if the ascertained present value of
the input signal is above the greater of the two limit values
and/or the value of the debounce status variable is lowered with
the second gradient if the ascertained present value of the input
signal is below the smaller of the two limit values. The at least
one limit value is thus replaced by a dead band as it were, wherein
the value of the debounce status variable is raised if the present
value of the input signal is above the dead band, and is lowered if
the present value of the input signal is below the dead band.
[0035] The object is furthermore achieved according to the
invention by a debouncing module, in particular a controller,
having a signal input for receiving an input signal, a signal
output for outputting an output signal and a signal processing
unit, wherein the signal processing unit is configured to perform a
method as described above. In consideration of the advantages and
features, reference is made to the explanations above in
consideration of the method, which accordingly also apply to the
debouncing module, and vice versa.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] Further advantages and properties of the invention are
obtained from the description below and the accompanying drawings,
to which reference is made and in which:
[0037] FIG. 1 schematically shows a block diagram of a debouncing
module according to the invention;
[0038] FIG. 2 shows a graph of an electrical input signal plotted
against time;
[0039] FIG. 3 shows (a) an enlarged detail from the electrical
input signal of FIG. 2 and (b) a graph of a resulting output signal
in the absence of debouncing for the input signal;
[0040] FIG. 4 schematically shows a flowchart for a method
according to the invention for debouncing the electrical input
signal;
[0041] FIG. 5 shows a graph of an output signal, debounced in
accordance with the method according to the invention from FIG. 4;
plotted again time; and
[0042] FIG. 6 shows a graph of the input signal plotted against
time to illustrate further aspects of the method according to the
invention.
DETAILED DESCRIPTION
[0043] FIG. 1 shows a debouncing module 10 that has a signal input
12 for receiving an electrical input signal x.sub.in(t), a signal
output 14 for outputting an electrical output signal x.sub.out(t)
and a signal processing unit 16.
[0044] The signal processing unit 16 is arranged in a manner
connected downstream of the signal input 12 and is connected to the
signal input 12 in signal-transmitting fashion. Further, the signal
processing unit 16 is arranged in a manner connected upstream of
the signal output 14 and is connected to the signal output 14 in
signal-transmitting fashion.
[0045] Expressed in a general way, the signal processing unit 16 is
designed to receive the electrical input signal x.sub.in via the
signal input 12, to process the input signal x.sub.inand to
generate the output signal x.sub.out on the basis of the input
signal x.sub.in.
[0046] FIG. 2 shows an exemplary depiction of the input signal
x.sub.in(t) in a manner plotted against time t. The input signal
x.sub.in is a superimposition comprising an interference-free
signal x.sub.in,id and interference, so that the value of the input
signal x.sub.in at least intermittently differs from the value of
the interference-free signal x.sub.in,id. This interference may be
random, that is to say can have a Gaussian distribution. However,
the interference can also have deterministic components.
[0047] In particular, the electrical input signal x.sub.in(t) is a
measurement signal from a sensor or is an already further-processed
measurement signal from a sensor. By way of example, the electrical
input signal x.sub.in(t) is the signal from a torque sensor, from
an angle position sensor, from a temperature sensor, from a voltage
sensor, from a current sensors and/or from a force sensor.
[0048] The applicable sensor from which the input signal x.sub.in
originates may be part of a steering system for a motor
vehicle.
[0049] Accordingly, the debouncing module 10 may be part of a
controller of a motor vehicle or of an applicable subsystem of a
motor vehicle.
[0050] Further, the input signal x.sub.in is an analog signal or a
digital signal, in particular a binary signal.
[0051] For many different applications, the signal processing unit
16 needs to ascertain whether a value of the interference-free
signal x.sub.in,id is above or below a predefined limit value
x.sub.G. It should be pointed out that the input signal x.sub.in in
FIG. 2 is indicated in units of the limit value x.sub.G, which is
why the value of the limit value x.sub.G is one.
[0052] The output signal x.sub.out is then a binary signal that is
produced by the signal processing unit 16 with one or two possible
different values, specifically depending on whether the value of
the interference-free input signal x.sub.in,id is above or below
the limit value x.sub.G. The two different possible values of the
output signal x.sub.out are denoted by E and below.
[0053] If the input signal x.sub.in, as shown in FIG. 2, has
high-frequency noise of non-negligible amplitude, it is difficult
to determine whether the value of the interference-free signal
x.sub.in,id is above or below the limit value x.sub.G.
[0054] This is illustrated once again in more detail in FIGS. 3(a)
and (b). FIG. 3(a) shows an enlargement of the range surrounded by
dots from FIG. 2 and FIG. 3(b) shows the applicable resulting value
of the output signal x.sub.out.
[0055] For the interference-free input signal x.sub.in,id, an
interference-free output signal x.sub.out,id is obtained that has a
single, step-shaped transition from to E.
[0056] For the actual input signal x.sub.in, on the other hand, a
greatly fluctuating output signal x.sub.out,r would be obtained
without further processing of the input signal x.sub.in on account
of the noise component.
[0057] To produce a stable output signal, the input signal x.sub.in
is thus processed by the debouncing module 10, to be more precise
by the signal processing unit 16.
[0058] Expressed in a general way, the debouncing module 10 is
designed to debounce the input signal x.sub.in and to take the
input signal x.sub.in as a basis for producing the output signal
x.sub.out. The output signal x.sub.out is thus a binary signal
having values E and that corresponds to the debounced input signal
x.sub.in.
[0059] To be more precise, the debouncing module 10 is designed to
perform the method for debouncing the electrical input signal
x.sub.in, that is described below with reference to FIGS. 4 to
6.
[0060] First, the electrical input signal x.sub.in is received via
the signal input 12 and forwarded to the signal processing unit 16
(step S1).
[0061] A present value of the input signal x.sub.in is then
ascertained (step S2). At this juncture and below, the "present
value" should be understood to mean a measurable signal parameter,
for example a present amplitude or a present power of the input
signal x.sub.in.
[0062] In step S2, the present value of the input signal x.sub.in
is additionally compared with the limit value x.sub.G. This
involves ascertaining whether the present value of the input signal
x.sub.in is above or below the limit value x.sub.G.
[0063] Additionally, a debounce status variable x.sub.E is produced
having a predefined initial value (step S3). The predefined initial
value is in a predefined range bounded by a minimum value W.sub.min
and a maximum value W.sub.max. In particular, W.sub.min is equal to
zero and W.sub.max is equal to 1. Naturally, any other isolated
range can also be used, however.
[0064] The initial value of the debounce status variable x.sub.E is
determined on the basis of the present value of the input signal
x.sub.in. To be more precise, the initial value is set equal to
W.sub.min if the present value of the input signal x.sub.in is less
than the limit value x.sub.G, and is set equal to W.sub.max if the
present value of the input signal x.sub.in is greater than the
limit value x.sub.G.
[0065] Alternatively, the initial value of the debounce status
variable x.sub.E may also be prescribed, however, for example as
zero or as one.
[0066] On the basis of the present value of the input signal
x.sub.in, the value of the debounce status variable x.sub.E is
altered (step S4). To be more precise, the value of the debounce
status variable x.sub.E is raised with a predefined first gradient
if the ascertained present value of the input signal x.sub.in is
above the limit value x.sub.G. Analogously, the value of the
debounce status variable x.sub.E is lowered with a second
predefined gradient if the ascertained present value of the input
signal x.sub.in is below the limit value x.sub.G.
[0067] The debounce status variable x.sub.E is always in the
predefined range. It thus cannot become less than the minimum value
W.sub.min or become greater than the maximum value W.sub.max.
[0068] At this juncture and below, "predefined gradient" means that
the first gradient and/or the second gradient are already
stipulated, that is to say constant, or are ascertained by the
signal processing unit 16 on the basis of stipulated criteria.
[0069] In FIG. 5, the resulting debounce status variable x.sub.E(t)
is plotted against time. The magnitude of the value of the first
gradient and the magnitude of the value of the second gradient are
equal in this case and independent of how far the present value of
the input signal x.sub.in is above or below the limit value
x.sub.G.
[0070] Alternatively, the first gradient and the second gradient,
to be more precise the magnitudes thereof, may also be different
from one another.
[0071] Additionally, the first and/or the second gradient may be
dependent on how far away the present value of the input signal
x.sub.in is from the limit value x.sub.G. The gradient of the
debounce status variable is then thus a function of the distance of
the present value of the input signal x.sub.in from the limit value
x.sub.G, that is to say
m=f(x.sub.in(t)-x.sub.G),
[0072] where m denotes the gradient. Expressed another way, the
gradient of the debounce status variable x.sub.E is thus
ascertained on the basis of a characteristic curve and/or another
computation code, the characteristic curve and/or the computation
curve being defined by the function f(x.sub.in(t)-x.sub.G).
[0073] Preferably, f is a monotonously rising function having a
zero crossing at x.sub.in(t)=x.sub.G, so that the magnitude of the
gradient is greater the further away the present value of the input
signal x.sub.in is from the limit value x.sub.G.
[0074] The output signal x.sub.out is produced on the basis of
whether the value of the debounce status variable x.sub.E is equal
to the minimum value W.sub.min, is equal to the maximum value
W.sub.max or corresponds to a value between the minimum value
W.sub.min and the maximum value W.sub.max (step S5).
[0075] As can be seen in FIG. 5, the value of the output signal
x.sub.out remains unaltered for as long as the value of the
debounce status variable x.sub.E is between the minimum value
W.sub.min and the maximum value W.sub.max.
[0076] When the debounce status variable x.sub.E reaches the
maximum value W.sub.max, however, which is the case at the time
t.sub.1 in FIG. 5, the value of the output signal x.sub.out is
changed to E.
[0077] Analogously, the value of the output signal x.sub.out is set
to again, only when the value of the debounce status variable
x.sub.E reaches the minimum value W.sub.min again.
[0078] In comparison with FIGS. 3 and 5, it can be seen that in
this manner the input signal x.sub.in is debounced efficiently with
a short delay.
[0079] FIG. 6 depicts a further graph of the input signal x.sub.in
in a manner plotted against time, on the basis of which two further
aspects, which can each be integrated into the method described
above on their own or else in combination, are described below.
[0080] Unlike in the method described above, there is provision in
this case not for a single limit value but rather for a first limit
value x.sub.G1 and a second limit value x.sub.G2. The limit value
x.sub.G is between the first limit value x.sub.G1 and the second
limit value x.sub.G2.
[0081] While the present value of the input signal x.sub.in is
between the first limit value x.sub.G1 and the second limit value
x.sub.G2, the value of the debounce status variable x.sub.E remains
unaltered.
[0082] Expressed in another way, the gradient of the debounce
status variable x.sub.E is thus set to zero for as long as the
present value of the input signal x.sub.in is between the first
limit value x.sub.G1 and the second limit value x.sub.G2.
[0083] The first limit value x.sub.G1 and the second limit value
x.sub.G2 thus define a dead band within which the debounce status
variable x.sub.E does not change.
[0084] Otherwise, the method for debouncing the input signal
x.sub.in proceeds analogously to that described above, wherein
above the first limit value x.sub.G1 the value of the debounce
status variable x.sub.E is raised and below the second limit value
x.sub.G2 the value of the debounce status variable x.sub.E is
lowered.
[0085] Alternatively or additionally, there is provision for a
positive limit value x.sub.P and a negative limit value x.sub.N.
The positive limit value x.sub.P is greater than the limit value
x.sub.G or than the first limit value x.sub.G1, and the negative
limit value x.sub.N is less than the limit value x.sub.G or than
the second limit value x.sub.G2.
[0086] The text below merely describes the case portrayed in FIG.
6, that is to say the case with the first limit value x.sub.G1 and
the second limit value x.sub.G2. However, the explanations that
follow also apply to the case of the single limit value x.sub.G,
apart from the dead band, which is then absent.
[0087] The multiple limit values x.sub.P, x.sub.N, x.sub.G1 and
x.sub.G2 define five bands that each correspond to a fixed,
predefined gradient of the debounce status variable.
[0088] To be more precise, the debounce status variable x.sub.E is
raised with a constant primary first gradient if the present value
of the input signal x.sub.in is between the first limit value
x.sub.G1 and the positive limit value.
[0089] If the present value of the input signal x.sub.in is greater
than the positive limit value x.sub.P, the debounce status variable
x.sub.E is raised with a constant secondary first gradient that is
greater than the primary first gradient.
[0090] If the present value of the input signal x.sub.in is between
the negative limit value x.sub.N and the second limit value
x.sub.G2, the present value of the debounce status variable x.sub.E
is lowered with a constant primary second gradient.
[0091] If the present value of the input signal x.sub.in is less
than the negative limit value x.sub.N, the debounce status variable
x.sub.E is lowered with a constant secondary second gradient, the
magnitude of which is greater than the magnitude of the primary
second gradient.
[0092] Expressed in another way, the limit values x.sub.P, x.sub.N,
x.sub.G1 and x.sub.G2 thus define the five bands within which the
gradient of the debounce status variable x.sub.E is constant in
each case, the gradient changing in the event of a transition
between the bands, however.
[0093] Naturally, there may also be provision for more than five
bands, for example by virtue of there being provision for multiple
positive limit values and/or multiple negative limit values.
[0094] Preferably, the magnitude of the gradient of the debounce
status variable x.sub.E increases with the distance from the limit
value x.sub.G in this case too.
* * * * *