CAN BUS Shield Help

Products & Technology Shields
#1

Hi all, i have been trying to get the CAN bus recieve code to work from the wiki site, i have one UNO R3 and sparkfun shield, i can transmit with the sent code and view on my CAN Analyser,

When i upload the Recieve code, and send out some data on address 0X00 as in the send code, and view the serial monitor, i see nothing at all,

I notice there is no serial.begin or serial.print code in the recieve code on the wiki site? is this correct?

Thanks for the help

Rich

#2

hey~ yes, there is something wrong in the wiki~ You need to add a code “Serial.begin()”. The guy who design the shield will refresh the wiki soon!

#3

Can you advise on what else is needed and at which point in the code you think it should go?

I have added the serial.begin(9600) to the code as shown below, but as soon as i iopen the serial monitor, it crashes the BUS.

#include “mcp_can.h”
#include <SPI.h>
#include <stdio.h>
#define INT8U unsigned char

INT8U Flag_Recv = 0;
INT8U len = 0;
INT8U buf[8];
char str[20];
void setup()
Serial.begin(115200); ADDED HERE
{
CAN.begin(CAN_500KBPS);
attachInterrupt(0, MCP2515_ISR, FALLING);
}

void MCP2515_ISR()
{
Flag_Recv = 1;
}

void loop()
{
if(Flag_Recv)
{
Flag_Recv = 0;
CAN.readMsgBuf(&len, buf);
if(buf[0] == 02 && buf[1] == 01 && buf[2] == 00)
{
unsigned char b[8] = {0x06, 0x41, 0x00 ,0xbe ,0x3f ,0xa8 ,0x13 ,0x00};
unsigned char c[8] = {0x06, 0x41, 0x00 ,0x98 ,0x1e ,0x80 ,0x13 ,0x00};
CAN.sendMsgBuf(0x7e8, 0, 8, b);
CAN.sendMsgBuf(0x7e9, 0, 8, c);

  }
  
  if(buf[0] == 02 && buf[1] == 01 && buf[2] == 0x0d)
  {
    unsigned char a[8] = {0x03 ,0x41 ,0x0d ,0x00 ,0x00 ,0x00 ,0x00 ,0x00};
    CAN.sendMsgBuf(0x7e8, 0, 8, a);
    CAN.sendMsgBuf(0x7e9, 0, 8, a);
  }
}

}

#4

it crashes the BUS ? hey, I am sorry that I can’t understand what you mean exactly, do you mean the can bus shield didn’t get anything or something else?

#5

I meant that the BUS became full of recieve errors,

Deray has now sent me a new library which works great,

Can you help with one issue,

When doing a CAN.readMsgBuf, is there any way of conditioning it to look at only a single specified CAN base Id, such as a message being sent with ID 0x400 for example?

I had a look in the keywords folder and thjere is a GetCANid command, but im unsure of how to implement this,

Thanks

Rich

#6

yes, when you had received a CAN-Bus frame (readMsgBuf()), you can use getCanId to get the ID of the frame~

#7

Hi, I saw this post which was quite some time back, however I am also using the sparkfun shield, and are unable to receive anything.

any suggestion on this?