Arduino MCP 2515 CAN BUS controller Library glitch?

Projects Programming
1

Im using the CAN Bus shield built as a circuit on a breadboard. It is identical to the shield. Im using the SeedStudio library here.

The problem is the Send sketch does not seem to working properly. I can send the correct data but then i cant stop or send something else.

// demo: CAN-BUS Shield, send data
#include <mcp_can.h>
#include <SPI.h>

// the cs pin of the version after v1.1 is default to D9
// v0.9b and v1.0 is default D10
const int SPI_CS_PIN = 9;

MCP_CAN CAN(SPI_CS_PIN);                                    // Set CS pin

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

START_INIT:

    if(CAN_OK == CAN.begin(CAN_500KBPS))                   // init can bus : baudrate = 500k
    {
        Serial.println("CAN BUS Shield init ok!");
    }
    else
    {
        Serial.println("CAN BUS Shield init fail");
        Serial.println("Init CAN BUS Shield again");
        delay(100);
        goto START_INIT;
    }
}

unsigned char stmp[8] = {0, 1, 2, 3, 4, 5, 6, 7};
void loop()
{
    // send data:  id = 0x00, standrad frame, data len = 8, stmp: data buf
    CAN.sendMsgBuf(0x00, 0, 8, stmp); //Works fine
        CAN.sendMsgBuf(0x01, 0, 8, stmp); //Does not work, the circuit loops at the first message. 
    delay(100);                       // send data per 100ms
}

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

The sketch executes the first send command correctly but then does not execute the second send command. All i get is the first (0x00) command on loop. Any insight will be appreciated!

2

The labels and goto statements are completely useless. There are grown up constructs that perform the same capabilities. Use them!

    CAN.sendMsgBuf(0x00, 0, 8, stmp); //Works fine
        CAN.sendMsgBuf(0x01, 0, 8, stmp); //Does not work, the circuit loops at the first message.

So, what do those arguments mean?

3

Yes Paul, i know goto statements are frowned upon. I did not write this, it is an example taken from the library.

 CAN.sendMsgBuf(0x00, 0, 8, stmp); //0x00 is the CAN identifier you want to send, 0 signifies a standard CAN frame, 8 specifies the number of bytes to send, stmp is the buffer containing the bytes you are sending.
4

I did not write this, it is an example taken from the library.

Then you should not expect any more from the library than the crap you are getting.

5

Have you managed to make it work?
It might be that you attempt to send before the buffer has magaed to send the first message. A delay between them might then help.

Or there is no other node on the network that can ACK your message.

I might find out within a week. I just got a few generic modules myself. :slight_smile:

/Dick