Purpose of this document

This document exists as a description of the individual 'modules' in the car's network, the communication protocol used between these modules, and codepage maps of these modules.

Module List

Module Name	Module Purpose
Climate Control Module (CCM)	To control the peltier array and solenoid valves that are used to regulate cabin tempurature
Host Interface Module (HIM)	To control power to the main system computer and to communicate between the main system computer and the rest of the bus
Main Module	To control power to the battery charger during charging and the power steering pump during vehicle operation, as well as collecting tach and vehicle speed data
User Interface Module	To control two LCD displays and collect data from a NES controllor, as well as driving two analog meters
Measurement Module	To collect data from onboard instrumentation including two RS232 interfaced DMMs

Communications Protocol Description

The communcations protocol is by neccessity simplistic - among other things, it is necccesary to impliment this protocol on computers with 128 bytes of RAM (!). So, that having been said, here is the basic idea. All modules connect togeather via two wires on a bus. The first wire is used for attention signalling, the second wire for data signalling. Normally, all modules service their process requests - however, when it becomes neccesary for a module to send data it brings the attention line low. Then that modules pauses for a time (stored in nvram) that corrisponds to the wakeup delay for the module that module is trying to address.

The module being addressed responds with it's own address. The calling module will retry the address until the called module responds, or until retry events occur (another variable stored in nonvoliatile memeory)

The module addressing then sends a instruction block, and then delays long enough for the module to recover (again, hardcoded value), and then sends a data block.

The instructions for this block are as follows:

Instruction #	Operation performed	Requires data block?	Returns Data Block?	Services a interrupt
0	ping the callee. The callee should respond with a system status block
1	write nonvolitile memory for (short) blocks starting at address (short). Length of program is compiled in in the static nonvolitile section using a DATA statement.
2	read nonvolitile memory for (short) blocks statrting at address (short)
3	write volitile scratchpad memory for (short) blocks starting at address (short).
4	read volitile scratchpad memory for (short) blocks starting at address (short)
5	service a interrupt request, non-urgent
6	service a interrupt request, urgent

The following nonvolatile memory addresses are reserved for network operations:

Memory location	Purpose
N0	Network bit settings
N1-N16	Delay values for module address wake up
N17	Number of times to retry transmission
N18	collision backoff

Climate Control Module

Line	Function	Direction	Initial level	Name of driving subroutine	Memory location (if applicable)
0	Comm Bus Tranceve	Bidirectional	Open	part of the comm library
1	Comm Bus attention	Bidirectional	Open	Part of the comm library
2	Reserved
3	Reserved
4	Radiator valve (closed = high, but overriden by fan_out on inverter, indicating water is too hot to use only the core to cool it)	Output	Low	raddrv:	V0
5	Header core valve (closed = high)	Output	High	coredrv:	V1
6	Main pump drive (operating = high, ORed with main drive operating)	Output	Low	mainpumpdrv:	V2
7	Peltier pump drive (operating = high)	Output	Low	auxpumpdrv	V3
8	heat pump engage (panel sw)	Input	Low	chkengage	V4
9	heat/cool slider	I/O	open	chkslider	V5
10	pelt heatsink left	I/O	open	chkthermistor	V6
11	pelt heatsink right	I/O	open	chkthermistor	V7
12	pelt coldplate intake	I/O	open	chkthermistor	V8
13	pelt coldplate output	I/O	open	chkthermistor	V9
14	peltier drive	I/O	open	drv	V10
15	peltier direction select (high=heat)	output	low	drv	V11

Psuedocode for climate control module

initilize lines
initilize comm library
while(1) {
	check attention line, service network if neccesary
	increment counter variable
	if counter variable is pegged, rese it
	if counter variable mod (rescan therm time) rescan thermistors
	if counter variable mod (rescan slider/control time) rescan slider/control
	gosub calculate_drive();
}

calculate_drive() :

	baseline = slider;
	if baseline > (configged core turnon) engage core;
	if baseline > (configged radiator cutout) cutout radiator;. (hardware will open radiator anyway if inverter's fan drive output is high
	if heatsinktemp1 or heatsinktemp2 > stored cutoff temp return
	if coldplateoutlettemp > stored cutoff temp return
	if heatsinktemp - coldplatetemp > stored efficient value and mode = cool return
	drive peltier line with output pulse, width determined by baseline - tempdiff lookup
}

User Interface Module

The user interface module is responsable for all communication between the user and the computer system (except for voice I/O, which is the subject of another document). The UI module can run in two modes, interrupt-generating and non-interrupt generating. In order to lower bus congestion, I suspect it will be desirable to run it in interrupt generating mode all the time, but the code is there either way.

You may wish to see this link to understand the NES controllor better. One other thing to bear in mind - there's a slight mod to the network call on this program. If the network must service a interrupt, it drives a time-scaled out pulse to the meters to keep them from 'dipping'. The IO lines on this module are assigned as follows:

Line	Function	Direction	Initial level	Name of driving subroutine	Memory location (if applicable)
0	Comm Bus Tranceve	Bidirectional	Open	part of the comm library
1	Comm Bus attention	Bidirectional	Open	Part of the comm library
2	Reserved
3	Reserved
4	LCD data bit 0	bidirectional	low	part of the LCD library
5	LCD data bit 1	bidirectional	low	part of the LCD library
6	LCD data bit 2	bidirectional	low	part of the LCD library
7	LCD data bit 3	bidirectional	low	part of the LCD library
8	LCD/NES strobe	out	Low	part of the LCD and NES libraries
9	LCD instruct/data, NES clock	out	Low	part of the LCD and NES libraries
10	LCD read/write	out	low	part of the LCD library
11	LCD 1 enable	out	low	part of the LCD library
12	LCD 2 enable	out	low	part of the LCD library
13	NES data in	in	open	part of the NES library
14	Meter 1 out	out	open	mtrdrv	V0
15	Meter 2 out	out	open	mtrdrv	V1

Complete psuedocode, including network functions:

Host Interface Module

See this for wiring notes on interface cable.