Code:
/* CCM Interaction Test Sketch for Arduino Mega 2560
This sketch pretends to be the PCM for a 1994 to 1995 Chevrolet Corvette.
It listens for the CCM poll request bytes (40 57 XX XX Checksum),
then sends the appropriate diagnostic string upon receipt.
The diagnostic string is idle values except for coolant temp,
which is either static (236F) or variable (based on ADC0 input).
This sketch works on the 1994 to 1995 Corvette. It may work for 1996.
1990-1991 Corvettes use shorter polls (40 55 6B) and have shorter responses.
To use for a 1990-1991 Corvette, change the sliding window to 3 bytes
and just use the following match code without checksum ifs:
((window[0] == 0x40) && (window[1] == 0x55) && (window[2] == 0x6B))
Then comment out the top lines with output[21] and use the ones
with output[15]. If using dynamic CTS, change output[20] in the
last line of code to output[14].
The 1992-1993 Corvettes use the same poll as the 94-96, but their response
is shorter. To use for a 92-93 Corvette, just comment out the top
lines with output[21] and use the ones with output[18]. If using
dynamic CTS, change output[20] in the last line of code to output[17].
This sketch only works on the Arduino Mega 2560 family.
This is because we're using Serial1, UCSR1B, RXEN1, RXCIE1.
If you want to try it on a different board, change these accordingly.
*/
#include <avr/io.h>
#include <wiring_private.h>
#include <FastLED.h>
byte window[5]; //define the 5-byte-wide sliding window
//byte output[21]= {0x41, 0x67, 0x02, 0xF5, 0x00, 0xCD, 0x87, 0x01, 0x00, 0x00, 0x00, 0x00, 0x88, 0x00, 0x48, 0xFF, 0xFF, 0x00, 0xFF, 0xFF, 0x40}; //define the static CTS message
//byte output[21]= {0x41, 0x67, 0x02, 0xF5, 0x00, 0x87, 0x87, 0x01, 0x00, 0x00, 0x00, 0x00, 0x88, 0x00, 0x48, 0xFF, 0xFF, 0x00, 0xFF, 0xFF, 0x86}; //define the dynamic CTS message
byte output[18]= {0x41, 0x64, 0x01, 0xF3, 0x00, 0xCD, 0x60, 0x01, 0x00, 0x6F, 0x0F, 0xD6, 0x83, 0x00, 0x51, 0xFF, 0xFF, 0x13}; //define 1992-1993 Corvette static CTS message
//byte output[18]= {0x41, 0x64, 0x01, 0xF3, 0x00, 0x5A, 0x60, 0x01, 0x00, 0x6F, 0x0F, 0xD6, 0x83, 0x00, 0x51, 0xFF, 0xFF, 0x86}; //define 1992-1993 Corvette dynamic CTS message
//byte output[15]= {0x41, 0x61, 0x00, 0xEC, 0x00, 0xCD, 0x39, 0x01, 0x00, 0x00, 0x00, 0xB4, 0x00, 0x39, 0x45}; //define 1990-1991 Corvette static CTS message
//byte output[15]= {0x41, 0x61, 0x00, 0xEC, 0x00, 0x39, 0x39, 0x01, 0x00, 0x00, 0x00, 0xB4, 0x00, 0x39, 0x12}; //define 1990-1991 Corvette dynamic CTS message
void setup() {
analogReference(DEFAULT); //Switch to default reference explicitly
pinMode(A0, INPUT); //Make sure A0 is an input explicitly
bitSet (DIDR0, ADC0D); //Disable digital buffer on A0
bitSet (DIDR0, ADC1D); //Disable digital buffer on A1
bitSet (DIDR0, ADC2D); //Disable digital buffer on A2
bitSet (DIDR0, ADC3D); //Disable digital buffer on A3
bitSet (DIDR0, ADC4D); //Disable digital buffer on A4
bitSet (DIDR0, ADC5D); //Disable digital buffer on A5
bitSet (DIDR0, ADC6D); //Disable digital buffer on A6
bitSet (DIDR0, ADC7D); //Disable digital buffer on A7
bitSet (DIDR1, AIN0D); //Disable digital buffer on AIN0
bitSet (DIDR1, AIN1D); //Disable digital buffer on AIN1
bitSet (DIDR2, ADC8D); //Disable digital buffer on A8
bitSet (DIDR2, ADC9D); //Disable digital buffer on A9
bitSet (DIDR2, ADC10D); //Disable digital buffer on A10
bitSet (DIDR2, ADC11D); //Disable digital buffer on A11
bitSet (DIDR2, ADC12D); //Disable digital buffer on A12
bitSet (DIDR2, ADC13D); //Disable digital buffer on A13
bitSet (DIDR2, ADC14D); //Disable digital buffer on A14
bitSet (DIDR2, ADC15D); //Disable digital buffer on A15
analogRead(0); //Burn an analog reading on A0
Serial1.begin(8192); //Open UART1 at 8192 baud
UBRR1H = (uint8_t)(121>>8); //Switch to 8192 baud at 1x
UBRR1L = (uint8_t)121; //Switch to 8192 baud at 1x
cbi(UCSR1A, U2X0); //disable 2x mode
cbi(UCSR1A, MPCM0); //disable multi-processor mode
cbi(UCSR1B, TXEN1); //disable transmitter for now
cbi(UCSR1B, TXCIE1); //disable transmit interrupts for now
FastPin<18>::setInput(); //tri-state TX1
}
void loop() {
if (Serial1.available()) {
// Slide the 5-byte window
for (uint8_t i = 0; i < 4; i++) {
window[i] = window[i + 1];
}
// Add new bytes as they come in
window[4] = Serial1.read();
// Check the first two bytes for a match
if ((window[0] == 0x40) && (window[1] == 0x57)) {
// Calculate the checksum byte
byte cs = 0;
for (uint8_t i = 0; i < 4; i++) {
cs += window[i];
}
cs = 0xFF - cs;
cs += 0x01;
// If checksum byte matches, send diagnostic data
if (cs == window[4]) {
cbi(UCSR1B, RXEN1); //disable receiver
cbi(UCSR1B, RXCIE1); //disable receive interrupts
window[0] = 0x00; //poison the sliding window
delay(2); //delay to allow ALDL line to settle
FastPin<18>::setOutput(); //reenable TX1 as Output
sbi(UCSR1B, TXEN1); //enable transmitter
sbi(UCSR1B, TXCIE1); //enable transmit interrupts
Serial1.write(output, sizeof(output)); //write the PCM diagnostic message
Serial1.flush(); //wait until transmit completes
cbi(UCSR1B, TXEN1); //disable transmitter
cbi(UCSR1B, TXCIE1); //disable transmit interrupts
FastPin<18>::setInput(); //tri-state TX1
sbi(UCSR1B, RXEN1); //reenable receiver
sbi(UCSR1B, RXCIE1); //reenable receive interrupts
}
}
}
//Read A0 to check status of potentiometer, save to cts byte
//output[5] = analogRead(0)>>2;
//Calculate new checksum and save to checksum byte
byte checksum = 0;
for (uint8_t i = 0; i < 20; i++) {
checksum += output[i];
}
checksum = 0xFF - checksum;
checksum += 0x01;
output[17] = checksum;
}
EDIT.. I think this line is wrong and I missed the modification specifically the 20 
Originally Posted by NomakeWan
Reply With Quote
Bookmarks