MCP2515 Interfaced with Arduino Mega using

Projects General Guidance
1

I am currently using the mcp_2515 library provided by cory fowler as posted. GitHub - coryjfowler/MCP_CAN_lib: MCP_CAN Library I am running into issues sending an extended CANBUS message. I have a CANBUS shield with a 16MHz Crystal with a MCP2515 and TJA1050. I have attached how I have the MCP2515 connected to the Mega as well as my code. Any help on how to get this working would be helpful!

ArduinoMega_MCP2515
ArduinoMega_MCP25151282×523 64.7 KB

Serial.println(sndStat,DEC); is returning a Timeout message

`// CAN Send Example
//

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

 MCP_CAN CAN0(53);     // Set CS to pin 10

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

 // Initialize MCP2515 running at 16MHz with a baudrate of 500kb/s and the masks and filters 
  disabled.
 while(CAN0.begin(MCP_ANY, CAN_500KBPS, MCP_16MHZ) != CAN_OK) 
Serial.println("MCP2515 Initializing");

Serial.println("Initialized MCP2515");

 CAN0.setMode(MCP_NORMAL);   // Change to normal mode to allow messages to be 
  transmitted
}

byte data[8] = {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07};

void loop()
{
   // send data:  ID = 0x100, Standard CAN Frame, Data length = 8 bytes, 'data' = array of data 
   bytes to send
   byte sndStat = CAN0.sendMsgBuf(0xFFA1, 1, 8, data);
    if(sndStat == CAN_OK){
   Serial.println("Message Sent Successfully!");
    } else {
    Serial.println(sndStat,DEC);
   }
  delay(3000);   // send data per 100ms

 }







  /******************
 END FILE

 *******/`
2

What 'issues' are you haing?

4

It is initializing fine. When it enters the main loop, it fails sending the message with an extended ID of "FFA1" with a code of 7 which is #define CAN_SENDMSGTIMEOUT (7). No idea why the message wont send

5

Are you testing in isolation or is it connected to a second MCP2515 or a CAN bus with active devices?
To test a sender you also need a receiver otherwise ACKS don't get set.

6

Ah it was in isolation. Will set up a receive device and get back

7

Wired up a second unit connected to an UNO and am running a receive example and still getting the error code...

// CAN Receive Example
//

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

long unsigned int rxId;
unsigned char len = 0;
unsigned char rxBuf[8];
char msgString[128];                        // Array to store serial string

#define CAN0_INT 2                              // Set INT to pin 2
MCP_CAN CAN0(10);                               // Set CS to pin 10


void setup()
{
  Serial.begin(115200);
  
  // Initialize MCP2515 running at 16MHz with a baudrate of 500kb/s and the masks and filters disabled.
  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);                     // Set operation mode to normal so the MCP2515 sends acks to received data.

  pinMode(CAN0_INT, INPUT);                            // Configuring pin for /INT input
  
  Serial.println("MCP2515 Library Receive Example...");
}

void loop()
{
  if(!digitalRead(CAN0_INT))                         // If CAN0_INT pin is low, read receive buffer
  {
    CAN0.readMsgBuf(&rxId, &len, rxBuf);      // Read data: len = data length, buf = data byte(s)
    
    if((rxId & 0x80000000) == 0x80000000)     // Determine if ID is standard (11 bits) or extended (29 bits)
      sprintf(msgString, "Extended ID: 0x%.8lX  DLC: %1d  Data:", (rxId & 0x1FFFFFFF), len);
    else
      sprintf(msgString, "Standard ID: 0x%.3lX       DLC: %1d  Data:", rxId, len);
  
    Serial.print(msgString);
  
    if((rxId & 0x40000000) == 0x40000000){    // Determine if message is a remote request frame.
      sprintf(msgString, " REMOTE REQUEST FRAME");
      Serial.print(msgString);
    } else {
      for(byte i = 0; i<len; i++){
        sprintf(msgString, " 0x%.2X", rxBuf[i]);
        Serial.print(msgString);
      }
    }
        
    Serial.println();
  }
}

/*********************************************************************************************************
  END FILE
*********************************************************************************************************/
8

Post a photo of the MCP2515 board.
Try to get everything in focus so you can see the writing on the crystal.

9

It is a 16Mhz crystal I am using fyi.

10

The outline of the board you posted looks like a Niren board and they ship with a 8MHz crystal. Have you made your own version of a Niren board with a 16MHz crystal?

11

Yes I soldered one on. I have the CAN communication working now. Did not jumper the terminator resistor. Onto the next step

12

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