U.S. patent application number 12/400683 was filed with the patent office on 2009-09-17 for multipurpose sensor port.
Invention is credited to Ammar Al-Ali, Rex J. McCarthy, Robert A. Smith.
Application Number | 20090234208 12/400683 |
Document ID | / |
Family ID | 34115356 |
Filed Date | 2009-09-17 |
United States Patent
Application |
20090234208 |
Kind Code |
A1 |
Al-Ali; Ammar ; et
al. |
September 17, 2009 |
Multipurpose Sensor Port
Abstract
A sensor port is adapted to connect to either a sensor or a data
source. A reader is configured to identify which of the sensor and
the data source is connected to the sensor port. A data path is
configured to communicate an analog signal associated with the
sensor and digital data associated with the data source to a signal
processor according to the identification made by the reader.
Inventors: |
Al-Ali; Ammar; (Tustin,
CA) ; Smith; Robert A.; (Lake Forest, CA) ;
McCarthy; Rex J.; (Mission Viejo, CA) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET, FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Family ID: |
34115356 |
Appl. No.: |
12/400683 |
Filed: |
March 9, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10898680 |
Jul 23, 2004 |
7500950 |
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12400683 |
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60490091 |
Jul 25, 2003 |
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Current U.S.
Class: |
600/323 ;
600/300 |
Current CPC
Class: |
A61B 5/0002 20130101;
A61B 2562/08 20130101; A61B 5/14552 20130101; A61B 2560/045
20130101; G16H 40/63 20180101; G05B 19/02 20130101; A61B 5/14551
20130101; A61B 5/02416 20130101 |
Class at
Publication: |
600/323 ;
600/300 |
International
Class: |
A61B 5/1455 20060101
A61B005/1455 |
Claims
1. A device configured to allow digital communication between a
sensor port of a patient monitor and a digital data source external
to the patient monitor, the device communicating over conductors at
times tasked with communicating analog drive signals to a sensor
and conductors at times tasked with communicating analog signals to
the patient monitor indicative of light detected by said sensor
that has been attenuated by body tissue, said device comprising a
sensor port interface configured to provide mechanical and signal
level compliance between said sensor port and said digital data
source, said sensor port digitally communicating through said
sensor port interface with said digital data source, said sensor
port communicating said analog signals with said sensor and wherein
only one of said sensor or said sensor port interface can be
connected with said sensor port at a time.
2. The device of claim 1 wherein the interface communicates digital
upgrade firmware data to the sensor port.
3. The device of claim 1 wherein the digital data source comprises
a PC and wherein the sensor port interface provides signal level,
mechanical, and communication protocol compliance to the output of
the PC.
4. The device of claim 3 wherein the PC transmits upgrade firmware
to the digital data interface, and wherein the interface translates
the upgrade firmware from a standard PC output signal into a sensor
port input signal and communicates the sensor input signal to the
sensor port.
5. The device of claim 1 wherein the digital data source comprises
a second physiological sensor and wherein the sensor port interface
communicates drive signals to the second physiological sensor and
wherein the physiological sensor generates digital data and
transmits the digital data through the sensor port interface to the
sensor port of the physiological measurement system.
6. The device of claim 1 wherein the digital data source comprises
a wireless data service.
7. The device of claim 1 wherein the digital data source employs a
network standard in its communication.
8. A method of adapting a communication bridge, said bridge between
a patient monitoring device and a physiological sensor the device
uses to acquire signals responsive to physiological parameters of a
patient to allow the device to determine measurement values for
said physiological parameters, said bridge accommodating
communication between said device and a digital data source, the
method comprising: providing an interface mechanically and
electrically connectable to a sensor port of the patient monitoring
device, the interface configured to communicate with the digital
data source, wherein the sensor port is also configured
mechanically and electrically connect to a physiological sensor
including emitters and one or more detectors adapted to detect
light from said emitters after attenuation by tissue at a tissue
site of said patient, said detected light responsive to said
parameters of said patient; and transmitting digital data between
the digital data source through the interface and to at least some
conductors associated with the sensor port wherein the at least
some conductors associated with the sensor port are also used to
communicate analog signals to the physiological sensor and wherein
only one of said sensor or said digital data source can be
connected with said sensor port at a time.
9. The method of claim 8 wherein the digital data further comprises
upgrade firmware for upgrading the firmware of the physiological
monitor.
10. The method of claim 9 wherein the digital data source comprises
non-volatile memory storing said upgrade firmware.
11. The method of claim 9 wherein the digital data source comprises
a PC storing said upgrade firmware.
12. The method of claim 8 wherein the digital data further
comprises measurement data from said physiological monitor.
13. The method of claim 12 wherein the digital data source
comprises non-volatile memory storing said measurement data.
14. The method of claim 12 wherein the digital data source
comprises a display.
15. The method of claim 12 wherein the display displays indicia
responsive to said measurement.
16. The method of claim 8 wherein the digital data source comprises
a PC and wherein the interface provides signal level, mechanical,
and communication protocol compliance to the output of the PC.
17. The method of claim 8 wherein the digital data source comprises
a second physiological sensor and wherein a drive signal is
communicated from the at least some conductors associated with the
sensor port, through the interface, to the physiological sensor and
wherein the physiological sensor generates raw digital data which
is communicated through the interface to the sensor port of the
physiological monitor.
18. The method of claim 8 wherein the digital data source is
comprises wireless data service.
19. A communication bridge adapted to communicate between an analog
sensor and a physiological measurement device and also adapted to
communicate between a digital data source and a physiological
measurement device, said bridge comprising: means for at one time
communicating digital data between a digital data source and a
sensor port of a physiological measurement system; and means for
communicating at another time between the sensor port of a
physiological measurement system an analog physiological sensor
including emitters and detector adapted to detect light from said
emitters after attenuation by tissue at a tissue site of said
patient.
20. The device of claim 19 wherein the digital data further
comprises upgrade firmware.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of application Ser. No.
10/898,680, entitled "Multipurpose Sensor Port," filed Jul. 23,
2004, and application Ser. No. 10/898,680 claims the benefit of
U.S. Provisional Application No. 60/490,091 filed Jul. 25, 2003,
entitled "Multipurpose Sensor Port." The present application
incorporates the disclosure of both of the foregoing applications
herein by reference.
BACKGROUND OF THE INVENTION
[0002] A pulse oximeter is a physiological instrument that provides
noninvasive measurements of arterial oxygen saturation along with
pulse rate. To make these measurements, a pulse oximeter performs a
spectral analysis of the pulsatile component of arterial blood so
as to determine the relative concentration of oxygenated
hemoglobin, the major oxygen carrying constituent of blood. Pulse
oximeters provide early detection of decreases in the arterial
oxygen supply, reducing the risk of accidental death and injury. As
a result, these instruments have gained rapid acceptance in a wide
variety of medical applications, including surgical wards,
intensive care units, general wards and home care.
[0003] FIG. 1 illustrates a pulse oximetry system 100 having a
sensor 110 and a monitor 120. The monitor 120 may be a
multi-parameter patient monitor or a standalone, portable or
handheld pulse oximeter. Further, the monitor 120 may be a pulse
oximeter 200, such as an OEM printed circuit board (PCB),
integrated with a host instrument including a host processor 122,
as shown. The sensor 110 attaches to a patient and receives drive
current from, and provides physiological signals to, the pulse
oximeter 200. An external computer (PC) 130 may be used to
communicate with the pulse oximeter 200 via the host processor 122.
In particular, the PC 130 can be used to download firmware updates
to the pulse oximeter 200 via the host processor 122, as described
below.
[0004] FIG. 2 illustrates further detail of the pulse oximetry
system 100. The sensor 110 has emitters 112 and a detector 114. The
emitters 112 typically consist of a red light emitting diode (LED)
and an infrared LED that project light through blood vessels and
capillaries underneath a tissue site, such as a fingernail bed. The
detector 114 is typically a photodiode positioned opposite the LEDs
so as to detect the emitted light as it emerges from the tissue
site. A pulse oximetry sensor is described in U.S. Pat. No.
6,088,607 entitled "Low Noise Optical Probe," which is assigned to
Masimo Corporation, Irvine, Calif. and incorporated by reference
herein.
[0005] As shown in FIG. 2, the pulse oximeter 200 has a preamp 220,
signal conditioning 230, an analog-to-digital converter (ADC) 240,
a digital signal processor (DSP) 250, a drive controller 260 and
LED drivers 270. The drivers 270 alternately activate the emitters
112 as determined by the controller 260. The preamp 220, signal
conditioning 230 and ADC 240 provide an analog front-end that
amplifies, filters and digitizes the current generated by the
detector 114, which is proportional to the intensity of the light
detected after tissue absorption in response to the emitters 112.
The DSP 250 inputs the digitized, conditioned detector signal 242
and determines oxygen saturation, which is based upon the
differential absorption by arterial blood of the two wavelengths
projected by the emitters 112. Specifically, a ratio of detected
red and infrared intensities is calculated by the DSP 250, and
arterial oxygen saturation values are empirically determined based
upon the ratio obtained. Oxygen saturation and calculated pulse
rate values are communicated to the host processor 122 for display
by the monitor 120 (FIG. 1). A pulse oximeter is described in U.S.
Pat. No. 6,236,872 entitled "Signal Processing Apparatus," which is
assigned to Masimo Corporation, Irvine, Calif. and incorporated by
reference herein.
[0006] Further shown in FIG. 2, the pulse oximeter 200 has a sensor
port 210 and a communications port 280. The sensor port 210
includes a connector and associated input and output signals and
provides an analog connection to the sensor 110. In particular, the
sensor port 210 transmits a drive signal 212 to the LED emitters
112 from the LED drivers 270 and receives a physiological signal
214 from the photodiode detector 114 in response to the LED
emitters 112, as described above. The communication port 280 also
includes a connector and associated input and output signals and
provides a bi-directional communication path 282 between the pulse
oximeter 200 and the host processor 122. The communication path 282
allows the DSP 250 to transmit oxygen saturation and pulse rate
values to the monitor 120 (FIG. 1), as described above. The
communication path 282 also allows the DSP firmware to be updated,
as described below.
[0007] Additionally shown in FIG. 2, the pulse oximeter 200 has a
micro-controller 290 and a flash memory 255. The flash memory 255
holds the stored program or firmware that executes on the DSP 250
to compute oxygen saturation and pulse rate. The micro-controller
290 controls data transfers between the DSP 250 and the host
processor 122. In particular, to update the DSP firmware, the
firmware is uploaded into the PC 130 (FIG. 1), which downloads the
firmware to the host processor 122. In turn, the host processor 122
downloads the firmware to the micro-controller 290, which downloads
it to the DSP 250. Finally, the DSP 250 writes the firmware to the
flash memory 255.
SUMMARY OF THE INVENTION
[0008] To update the firmware in a pulse oximeter, particularly
firmware on an OEM PCB integrated into a host instrument, requires
a circuitous path using multiple protocols and multiple processors
developed by different companies. Some of the protocols and
processor interfaces are non-standard, requiring custom programming
for different instruments. This is particularly problematic when
the instruments are part of an installed base at various medical
facilities. Further, some pulse oximeter products, such as handheld
products, may not have a communications port for connecting to an
external computer, and firmware upgrades would typically require
returning the instrument to the factory.
[0009] Every pulse oximeter has a sensor port, which provides
access to a DSP via one or more signal paths. Therefore, it is
desirable to utilize a sensor port for downloading pulse oximetry
firmware to the DSP. It is also desirable to provide this sensor
port capability in existing instruments without hardware
modification. Utilizing a sensor port in this manner would
alleviate an instrument manufacturer from having to provide
download communication capability between a host processor and an
OEM PCB and would allow easy field upgrades of all instruments,
including handhelds.
[0010] One aspect of a multipurpose sensor port is a physiological
measurement method comprising a sensor port adapted to connect with
an analog sensor, and a digital data source connected to the sensor
port. An identifier associated with said data source is read, where
the identifier is indicative that the data source is connected to
the sensor port in lieu of the analog sensor. Digital data is then
received over the sensor port. In one embodiment, the digital data
is compiled in a signal processor. Where the digital data are
instructions executable by the signal processor, the data may then
be written from the signal processor into a firmware memory. The
instructions may be uploaded to a PC, which is attached to a PC
interface that is attached to the sensor port. Alternatively, the
instructions are stored into a nonvolatile memory that is in
communications with the sensor port. In another embodiment, the
digital data is processed as a physiological signal.
[0011] Another aspect of a multipurpose sensor port is a
physiological measurement system having a sensor port adapted to
connect to a sensor and a data source. A reader is configured to
identify which of the sensor and the data source is connected to
the sensor port. A data path is configured to communicate an analog
signal associated with the sensor and digital data associated with
the data source to a signal processor according to the reader. In
one embodiment, a firmware memory is configured to provide
instructions to the signal processor. The signal processor is
programmed to download the instructions from the data source and
store the instructions in the memory. The instructions are
executable by the signal processor so as to extract a physiological
measurement from the analog signal. The data source may be a PC
interfaced to the sensor port, where the instructions are uploaded
to the PC. Alternatively, the data source is a nonvolatile memory
adapted to communicate with the sensor port, where the instructions
being stored in a nonvolatile memory.
[0012] In another embodiment, a first physiological measurement is
derivable by the signal processor from the analog signal, and a
second physiological measurement is derivable by the signal
processor from the digital data. In yet another embodiment, a drive
path is configured to communicate stored data associated with a
physiological measurement to a digital device connected to the
sensor port. The stored data may be trend data and/or log data
maintained in memory that can be accessed by the signal processor.
In a further embodiment, a drive path is configured to communicate
acknowledgement data in conjunction with the communication of the
digital data.
[0013] Yet another aspect of a multipurpose sensor port is a
physiological measurement method where a drive path is provided
that is adapted to activate emitters so as to transmit optical
radiation through a fleshy medium having flowing blood. A signal
path is provided that is adapted to communicate a detector response
to the optical radiation after attenuation by the fleshy medium,
where the response is indicative of optical characteristics of the
flowing blood. Output digital data is transmitted over at least a
portion of the drive path. In one embodiment, the output digital
data is read from a memory having trend data and/or log data. In
another embodiment, input digital data is received over at least a
portion of the signal path, and receipt of that input digital data
is acknowledged with the output digital data. In a particular
embodiment, the input digital data is stored for use as signal
processing instructions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a general block diagram of a prior art pulse
oximeter system utilizing an OEM printed circuit board (PCB);
[0015] FIG. 2 is a detailed block diagram of a prior art pulse
oximeter system;
[0016] FIGS. 3A-D are general block diagrams of a multipurpose
sensor port connected to an analog sensor, a digital data source,
or both;
[0017] FIG. 4 is a general block diagram of a multipurpose sensor
port having various digital data source inputs;
[0018] FIG. 5 is a block diagram of a multipurpose sensor port
configured to download pulse oximeter firmware;
[0019] FIG. 6 is a DSP firmware memory map;
[0020] FIG. 7 is a detailed block diagram of a multipurpose sensor
port embodiment and associated signal and data paths;
[0021] FIG. 8 is a flowchart of a digital data receiver routine;
and
[0022] FIG. 9 is a schematic of a RS232 interface for a
multipurpose sensor port.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Overview
[0023] FIGS. 3A-B illustrate a pulse oximeter 300 having a
multipurpose sensor port 301 connected to an analog sensor 310 and
a digital data source 320, respectively. As shown in FIG. 3A, if
the pulse oximeter 300 determines that an analog sensor 310 is
attached to the multipurpose sensor port 301, the multipurpose
sensor port 301 is operated in an analog mode and functions as a
typical sensor port, described above. As shown in FIG. 3B, if the
pulse oximeter 300 determines that a digital data source 320 is
attached to the multipurpose sensor port 301, the multipurpose
sensor port 301 is operated in a digital mode and functions as a
digital communications device. The data source 320 may connect to a
sensor port interface 330 which, in turn, connects to the sensor
port 301. The sensor port interface 330 may be used, for example,
to present a standard communications interface, such as RS-232, to
the data source 320. In one embodiment, when the pulse oximeter 300
is powered up, it reads an information element or other means of
identification (ID) for the device connected to the sensor port
301. The ID identifies the device as either an analog sensor 310 or
a data source 320. A sensor information element is described in
U.S. Pat. No. 6,397,091 entitled "Manual and Automatic Probe
Calibration," which is assigned to Masimo Corporation, Irvine,
Calif. and incorporated by reference herein.
[0024] FIG. 3C illustrates a sensor port embodiment where a
resistor value is a device ID. A resistor 303 is located in a
device 302, which includes a sensor 310 (FIG. 3A), data source 320
(FIG. 3B) or interface 330 (FIG. 3B). The sensor port 301 has a
reader 304 that measures the resistor value. The reader 304
includes a voltage source 305 and a current measurement device 307,
such as a current-to-voltage converter. The voltage source 305 has
a known voltage, which is applied to the resistor 303 when the
device 302 is connected to the sensor port 301. The current
measurement device 307 senses the magnitude of the resulting
current flowing through the resistor 303 so as to determine the
resistor value and, hence, the device ID.
[0025] FIG. 3D illustrates a pulse oximeter 300 having an analog
sensor 310, a digital data source 320 and a switch 360 connected to
a multipurpose sensor port 301. If the pulse oximeter 300 reads an
ID that identifies mixed analog and digital, then the multipurpose
sensor port 301 functions to transfer either an analog signal or
digital data, as determined by the switch 360. The state of the
switch 360 may be determined by the data source 320, the pulse
oximeter 300 or both. In one embodiment, the pulse oximeter 300
transmits an identifiable waveform over an LED drive path 510 (FIG.
5) that is recognized by the switch 360 as a change state command.
In this manner, the pulse oximeter 300 may occasionally receive
digital data from, or transmit digital data to, the data source
320.
Applications
[0026] FIG. 4 illustrates various digital data source 320 and
sensor port interfaces 330 that connect to a multipurpose sensor
port 301. In one application, a preprogrammed module 405 connects
directly to the sensor port 301. The module 405 has nonvolatile
memory preprogrammed with, for example, upgrade firmware for the
pulse oximeter 300. The module 405 also has the associated
electronics to readout the memory data and communicate that data to
the sensor port 301. In particular, the module 405 provides
mechanical, signal level, and communication protocol compliance
with the sensor port 301.
[0027] As shown in FIG. 4, in another application, a PC 410
connects to the sensor port 301 via a PC interface 450. For
example, the PC 410 can be used to download firmware to the pulse
oximeter 300, as described with respect to FIG. 5, below. As
another example, the PC 410 can be used to upload information from
the pulse oximeter 300, as described with respect to FIG. 6, below.
In one embodiment, the PC interface 450 provides mechanical and
signal level compliance with RS-232 on the PC side and mechanical
and signal level compliance with the sensor port 301 on the pulse
oximeter side, as described with respect to FIG. 9, below.
[0028] Also shown in FIG. 4, a physiological sensor 420 other than
a conventional pulse oximeter sensor is attached to the
multipurpose sensor port 301. A physiological sensor interface 460
drives the physiological sensor 420 and generates raw digital data
to the sensor port 301. In this manner, a pulse oximeter 300 can be
advantageously extended to provide physiological measurements in
addition to oxygen saturation and pulse rate.
[0029] Further shown in FIG. 4, a wireless data device 430 is
attached to the multipurpose sensor port 301 via a wireless
interface 470. In this manner, the pulse oximeter can be
advantageously extended to wireless data I/O and wireless networks.
In one embodiment, the wireless interface 470 provides mechanical
and signal level compliance with a wireless standard, such as
IEEE-802.11, on one side and mechanical and signal level compliance
with the sensor port 301 on the pulse oximeter side.
[0030] Additionally shown in FIG. 4, networked digital I/O devices
440 are attached to the multipurpose sensor port 301 via a network
interface 480. In one embodiment, the network interface 480
provides mechanical and signal level compliance with a network
standard, such as Ethernet, on one side and mechanical and signal
level compliance with the sensor port 301 on the pulse oximeter
side.
Firmware Upgrade Port
[0031] FIG. 5 illustrates a multipurpose sensor port 301 configured
to download pulse oximeter firmware 501. The firmware 501 is
uploaded to a PC 410 and downloaded over a standard communications
bus 503 to a target pulse oximeter 300. The standard bus 503 may
be, for example, RS-232, IEEE-488, SCSI, IEEE-1394 (FireWire), and
USB, to name just a few. A PC interface 450 translates the signal
levels on the sensor port 301 to the signal levels of the standard
bus 503, and vice-a-versa. In particular, an output signal on the
standard bus 503 is translated to a sensor port input signal 522,
and a sensor port output signal 512 is translated to an input
signal on the standard bus 503.
[0032] As shown in FIG. 5, the pulse oximeter 300 has a detector
signal path 520, a DSP 530, a flash memory 540 or other nonvolatile
memory and a LED drive path 510, such as described with respect to
FIG. 2, above. Data transmitted from the PC 410 is carried on the
sensor port input 522, over the detector signal path 520 to the DSP
530, which loads the data into a flash memory 540. Acknowledgement
data is transmitted from the DSP 530, over the LED drive path 510,
and is carried on the sensor port output 512.
[0033] FIG. 6 illustrates a memory map 600 for the DSP flash memory
540 (FIG. 5). The memory map 600 illustrates partitions for DSP
executable instructions such as boot firmware 610, signal
processing firmware 620 and sensor port communications firmware 630
in addition to application data 640. The boot firmware 610 executes
upon DSP power-up. The boot firmware 610 initializes the DSP and
loads either the signal processing firmware 620 or the
communications firmware 630 into DSP program memory, depending on
the device ID, as described with respect to FIGS. 3A-D, above. The
signal processing firmware 620 contains the oxygen saturation and
pulse rate measurement algorithms, referred to with respect to
FIGS. 1-2, above. The communications firmware 630 contains
communications protocol algorithms, such as described with respect
to FIG. 8, below. After completing its task of downloading firmware
and/or uploading the applications data 640, the communications
firmware 630 loads the signal processing firmware 620 so that the
DSP can perform pulse oximetry measurements.
[0034] Also shown in FIG. 6, the application data 640 includes
trend data 632, operational logs 634 and manufacturer's logs 638,
which can be advantageously uploaded to a PC 410 (FIG. 5) or other
digital device connected to the sensor port 301 (FIG. 5). Trend
data 632 contains oxygen saturation and pulse rate measurement
history. Operational logs 634 contain, for example, failure codes
and event information. Failure codes indicate, for example, pulse
oximeter board failures and host failures. Event information
includes alarm data, such as the occurrence of probe off and low
saturation events. Manufacturer's logs 638 contains, for example,
service information.
[0035] FIG. 7 illustrates a multipurpose sensor port embodiment 301
incorporating an LED drive path 510, a detector signal path 520 and
a DSP 530, which function generally as described with respect to
FIG. 5, above. The LED drive path 510 has a shift register 710, a
red LED drive 720 and an IR LED drive 730. The shift register 710
has a data input 712, a red control output 714 and an IR control
output 718. The DSP 530 provides serial control data on the shift
register input 712 that is latched to the shift register outputs
714, 718 so as to turn on and off the LED drives 720, 730 according
to a predetermined sequence of red on, IR on and dark periods. The
detector signal path 520 has a preamp 740, signal conditioning 750
and an ADC 760 that perform amplification, filtering and
digitization of the detector signal 522. The detector signal path
520 also has a comparator 770 that compares the preamp output 742
to a fixed voltage level and provides an interrupt output 774 to
the DSP 530 accordingly. The comparator 770 allows the DSP to
control the preamp voltage as a function of the level of the preamp
signal output 742, as described in U.S. patent application Ser. No.
10/351,961 entitled "Power Supply Rail Controller," filed Jan. 24,
2003, which is assigned to Masimo Corporation, Irvine, Calif. and
incorporated by reference herein. Advantageously, the comparator
signal path also allows the DSP to accept serial digital data, as
described with respect to FIG. 8, below.
[0036] FIG. 8 illustrates a serial data receiver 800 embodiment of
one aspect of the communications firmware 630 (FIG. 6). The data
receiver 800 utilizes the detector signal path 520 (FIG. 7)
described above. A DSP internal timer is initialized to generate an
interrupt at the incoming data baud rate. The timer interrupt
periodically starts the data receiver 800 to determine and store a
single bit. The data receiver 800 polls the status of the DSP
interrupt input 774 (FIG. 7), which is initialized to be
level-sensitive and disabled. Thus, whenever the comparator 770
(FIG. 7) is triggered, it will latch into a DSP interrupt pending
register but will not generate an interrupt event. The timer
service routine 800 polls the interrupt pending register 820. The
pending register value is determined 830. If the value is a "1,"
then a zero bit has been received 840, else a one bit has been
received 850. The received bit is stored 860 and the timer reset
870.
[0037] FIG. 9 illustrates an RS-232 PC interface embodiment 450
having an RS-232 connector 910, a sensor connector 920, a voltage
regulator 930 and a transceiver 940. The voltage regulator 930
draws power from either the RS-232 910 RTS (request to send) or DTR
(data terminal ready) signal lines and provides regulated VCC power
to transceiver 940. The transceiver 940 operates on either of the
sensor 920 red or IR drive signal lines to generate an RS-232 910
RXD (receive data) signal. The transceiver 940 further operates on
the RS-232 TXD (transmit data) signal line to generate a sensor 920
detector signal.
[0038] A multipurpose sensor port has been disclosed in detail in
connection with various embodiments. These embodiments are
disclosed by way of examples only and are not to limit the scope of
the claims that follow. One of ordinary skill in the art will
appreciate many variations and modifications.
* * * * *