Tiva C and Max31865

[leahy268 0]

Hi everyone,

 

Long time reader rare poster.  So anyway long story short.  I have been trying to get my SSI module working with this for about 2 weeks with the Max31865.  On my logic analyser I am definitely getting signal.  I have been trying every code sample that I can find both energia\arduino samples and any others that I can find.  However as all that I get back from it is 0x00's or 0xff's I think I'm missing something.  

 

Does anyone have any sample code that definitely works on Tiva?  I own a tm4c123 launchpad.  Nothing I can do seems to work.  I don't know if it's the max31865 or my Tiva is broken or what the problem is.  I am planning on borrowing a raspberry Pi which I do have working code for to test the max31865 board.  

 

Thanks in advance for anyones help...

[spirilis 1,265]

Maybe the wiring is wrong?  I have no issues talking to a MAX31855 with my Tiva LP fwiw.  I don't know anything about the MAX31865 but I'd be shocked if it worked much different...

 

Be sure the Chip Select line is left in a HIGH state when inactive and pulled low before any SPI comms.

 

e.g. if the MAX31865 CS line is connected to pin 4,

void setup() {
  pinMode(4, OUTPUT);
  digitalWrite(4, HIGH); // set INACTIVE
  SPI.begin();
  Serial.begin(115200);
}

void loop() {
  // Read from the chip
  digitalWrite(4, LOW);  // MAX31865 is now ACTIVE and will clock out bytes
  uint8_t fourbyte[4];
  fourbyte[0] = SPI.transfer(0);
  fourbyte[1] = SPI.transfer(0);
  fourbyte[2] = SPI.transfer(0);
  fourbyte[3] = SPI.transfer(0);
  digitalWrite(4, HIGH);  // Deactivate MAX31865 so it releases MISO line for other SPI devices.

  Serial.print("Output: ");
  int i;
  for (i=0; i < 4; i++) {
    Serial.print(fourbyte[i], HEX);
    Serial.print(' ');
  }
  Serial.println();
  delay(1000);  // wait 1 second then do it again
}