Revision B
MAC
™
5000 resting ECG analysis system
2-31
2024917-010
Equipment Overview:
Theory of Operation
processor in the wrong spot on the board and a single pile of paperwork
supports all of the MAC 5000’s 68HC05 production volume. More
detailed information may be found in the source code.
Startup Self Identification
As each controller is released from reset, it executes a common
“WhoAmI” routine to determine its identity on the board. Each
controller’s environment is uniquely and easily identified with a few port
pin tests. Once the identity is discovered, the code jumps to the
appropriate entry point in the unified image and microcontroller
assumes the desired personality.
The flow for the “WhoAmI” routine is as follows:
Run ChkMoe:
Basically if the BBus (PD5) is low we are Moe. Since
Moe controls the power supply for +3V-M which is off at the moment,
the BBus pull-up resistors will actually pull the BBus lines low. This
can only occur with Moe since all other Stooges are powered by +3V-
M, Moe is powered by +3V-C instead.
Run ChkCurly:
Though the Curly is removed, the firmware related
to Curly is still present, for backward compatibility.
Run ChkShemp:
If bit 4 of Port A is high, we are Shemp. At this
point we are either Shemp or Larry. Shemp has pull-up resistors on
Port A so bit 4 should be high. Larry on the other hand has uses
Port A to drive a makeshift DAC. Since Port A is not being driven at
the moment, bit 4 will be pulled to low via the common DAC resistor
R136 which is grounded.
We must be Larry.
At this point we have eliminated all other
Stooges.
BBus
All three stooges (Moe, Larry and Shemp) communicate with the ATMEL
CPU via BBus connections. BBus is a single wire, half-duplex serial
connection that places minimal hardware requirements on the
microcontroller while yielding respectable bit transfer rates (~50KBps).
A common set of BBus commands allow the ATMEL CPU to access 128
bytes of RAM in each microcontroller. This dual port access allows the
ATMEL CPU to examine and modify internal variables in each controller
while code is executing. This ability is used to allow the unalterable
HC05 code to handle modest changes in hardware, such as changes in
paper drive gearing or battery pack capacity.
Shemp
Similar in function to the ABus keyboard controller in Max-1
architecture machines, Shemp scans the keyboard and queues key
presses for the ATMEL CPU. Unlike previous designs, key presses are
reported both on press and release, allowing system software to
implement auto-repeat as well as the continuous operation of treadmill
control keys (up/down, faster/slower). A special key code indicates when
all keys are up as a safeguard against stuck keys in the application
software.
Содержание MAC 5000
Страница 9: ...Revision B MAC 5000 resting ECG analysis system 1 1 2024917 010 1 Introduction ...
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Страница 59: ...Revision B MAC 5000 resting ECG analysis system 3 1 2024917 010 3 Installation ...
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Страница 77: ...Revision B MAC 5000 resting ECG analysis system 4 1 2024917 010 4 Maintenance ...
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Страница 103: ...Revision B MAC 5000 resting ECG analysis system 5 1 2024917 010 5 Troubleshooting ...
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Страница 135: ...Revision B MAC 5000 resting ECG analysis system 6 1 2024917 010 6 Parts List ...
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Страница 143: ...Revision B MAC 5000 resting ECG analysis system A 1 2024917 010 A Appendix A Abbreviations ...
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Страница 155: ...Revision B MAC 5000 resting ECG analysis system B 1 2024917 010 B Appendix B Technical Specifications ...
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Страница 163: ...Revision B MAC 5000 resting ECG analysis system C 1 2024917 010 C Appendix C Electromagnetic Compatibility ...
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Страница 171: ...Revision B MAC 5000 resting ECG analysis system Index 1 2024917 010 Index ...
Страница 172: ...Index 2 MAC 5000 resting ECG analysis system Revision B 2024917 010 ...
Страница 174: ...Index Index 4 MAC 5000 resting ECG analysis system Revision B 2024917 010 ...
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