Looking for asistance with ALDL project...

[steveo]

oh man that's like cheating!

[steveo]

you should try to 0xff some of the unused bytes just for fun to see if any undocumented stuff lights up

[steveo]

have you decided what you’re going to write the code with? arduino c?

[Quaraxkad]

I've ordered an Arduino Uno, it will be here tomorrow. I believe it's C++, not C. First step is basically just the example code shown here: https://www.arduino.cc/reference/en/.../serial/write/. Except I'll swap the hello string for the 0A 58 40 0D AC byte sequence and the proper 8192 baud rate. If I've done my math correctly and it works, that should give me a tach reading of 3500.

[steveo]

right on

here's a general function to generate a checksum byte with c or c++, just run it against the array

char checksum_generate(char *buf, int len) {
  int x = 0;
  unsigned int sum = 0;
  for(x=0;x<len;x++) sum += buf[x];
  return ( 256 - ( sum % 256 ) );
}

here's a function to test an incoming checksum (not that you should have to for this program)

bool checksum_test(char *buf, int len) {
  int x = 0;
  unsigned int sum = 0;
  for(x=0;x<len;x++) sum += buf[x];
  if((sum & 0xFF) == 0) {
    return true;
  } else {
    return false;
  }
}

[Quaraxkad]

Ah yes, I had completely forgotten about the checksum! Adding in your checksum function, this is pretty much the entirety of the initial test! I'm leaving out all of the other bytes because I expect they are uneccessary. I'm assuming the gauge cluster will only look at the 5 bytes after 0x0A.

void setup() {
  Serial.begin(8192);
}

void loop() {
  if (Serial.availableForWrite() > 5) {
    byte b[5] = {0x0A, 0x58, 0x40, 0x0D, 0xAC};

    unsigned int x, sum = 0;
    for (x = 0; x < sizeof(b); x++) sum += b[x];
    byte cs = ( 256 - ( sum % 256 ) );

    Serial.write(b, 5);
    Serial.write(cs);
  }
}

It compiles without errors or warnings, but that doesn't mean my logic is sound!

[Quaraxkad]

Adding a little math to convert an integer RPM into MSB and LSB...

void setup() {
  Serial.begin(8192);
}

void loop() {
  if (Serial.availableForWrite() > 5) {
    int rpm = 3200;
    byte msb = floor(rpm / 256);
    byte lsb = rpm % 256;
    
    byte b[5] = {0x0A, 0x58, 0x40, msb, lsb};

    unsigned int x = 0, sum = 0;
    for (x = 0; x < sizeof(b); x++) sum += b[x];
    byte cs = ( 256 - ( sum % 256 ) );

    Serial.write(b, 5);
    Serial.write(cs);
  }
}

Now if that works, I will add a potentiometer and read that for input to convert to an rpm reading, and I should be able to control my tachometer in real time!