leafdtc.ino

#include <mcp_can.h>
#include <SPI.h>

#define CAN0_CS 10 /* Set CS to pin 10 */

MCP_CAN CAN0(CAN0_CS); /* Set CS to pin 10 */

// UDS request for DTCs
unsigned char stmp[8] = {0x19, 0x02, 0xFF, 0x00, 0x00, 0x00, 0x00, 0x00};

// Flow control frame
unsigned char flowControlFrame[8] = {0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};

// Buffer for multi-frame messages
unsigned char multiFrameBuffer[255];
unsigned char multiFrameIndex = 0;
unsigned char multiFrameExpectedIndex = 1; // For checking frame sequence

// Rate limiter
unsigned long lastRequestTime = 0;
const unsigned long requestInterval = 2000; // Send request every 2 seconds

void setup() {
  Serial.begin(115200);

  if (CAN0.begin(MCP_ANY, CAN_500KBPS, MCP_16MHZ) == CAN_OK) {
    Serial.println("MCP2515 Initialized Successfully!");
  } else {
    Serial.println("Error Initializing MCP2515...");
  }
  
  CAN0.setMode(MCP_NORMAL);
}

void loop() {
  unsigned char len = 0;
  unsigned char buf[8];
  unsigned long rxId;

  if (CAN0.readMsgBuf(&rxId, &len, buf) == CAN_OK) { // If message received
    if (rxId == 0x78C) { // If message is from target ECU
      // First frame of a multi-frame message
      if (buf[0] >> 4 == 0x1) {
        multiFrameIndex = 0;
        multiFrameExpectedIndex = 1;
        int numBytes = ((buf[0] & 0x0F) << 8) | buf[1];
        for (int i = 2; i < len; i++) {
          multiFrameBuffer[multiFrameIndex++] = buf[i];
        }
        CAN0.sendMsgBuf(0x784, 0, 8, flowControlFrame); // Send flow control frame
      }
      // Consecutive frame
      else if (buf[0] >> 4 == 0x2) {
        if ((buf[0] & 0x0F) != multiFrameExpectedIndex) {
          Serial.println("Received frame out of order");
          return;
        }
        multiFrameExpectedIndex = (multiFrameExpectedIndex % 0x0F) + 1;
        for (int i = 1; i < len; i++) {
          multiFrameBuffer[multiFrameIndex++] = buf[i];
        }
        if (multiFrameExpectedIndex == 0x0F) {
          // We have received all frames of the multi-frame message
          printDTCs(multiFrameBuffer, multiFrameIndex);
        }
      }
      // Single frame
      else if (buf[0] >> 4 == 0x0) {
        printDTCs(&buf[1], len - 1);
      }
    }
  } else { // If no message is received
    unsigned long now = millis();
    if (now - lastRequestTime > requestInterval) { // If enough time has passed since last request
      CAN0.sendMsgBuf(0x784, 0, 8, stmp); // Send request to target ECU
      lastRequestTime = now; // Update last request time
    }
  }
}

// Helper function to print DTCs
void printDTCs(unsigned char* data, unsigned char len) {
  for (int i = 0; i < len; i += 2) {
    String dtc;
    
    // First character
    switch (data[i] >> 6) {
      case 0: dtc += 'P'; break;
      case 1: dtc += 'C'; break;
      case 2: dtc += 'B'; break;
      case 3: dtc += 'U'; break;
    }
    
    // Second character
    dtc += (data[i] & 0x20) ? '1' : '0';
    
    // Third character
    dtc += String((data[i] & 0x1C) >> 2);
    
    // Fourth and fifth characters
    dtc += String(((data[i] & 0x03) << 2) | ((data[i+1] & 0xC0) >> 6));
    dtc += String(data[i+1] & 0x3F);
    
    Serial.print("DTC: ");
    Serial.println(dtc);
  }
}