[En-Nut-Discussion] SJA1000

[Petri Hyötylä]

Thank you for quick and helpful response.
I am using a solderless breadboard and one wire was misplaced.

Now I have another problem. I am testing the CAN-circuit with
Peak System CAN debugger (Opto-decoupled USB-CAN Interface,
www.peak-system.com)
and I noticed a small discrepancy with it. I wrote some code that
sends the frames that it receives back to the bus with identical ID
and slightly altered
data bytes.

It seems that it works when I send frames with extended ID but when I send
frames with standard ID it returns a frame with ID with bits shifted
three bits
right. I guess that was not the best way to describe it but maybe
example helps.

Sent ID means the ID that the debugger sends and so on.
Sent ID:     0x050 (0000 0101 0000)
Received ID: 0x00A (0000 0000 1010)

Sent ID:     0x500 (0101 0000 0000)
Received ID: 0x0A0 (0000 1010 0000)

I tested with about 50 different combinations but I guess these two examples
suffice. Please Help. The code I used follows.
---------------------------------------------------------------------------
CANFRAME txCanFrame;
CANFRAME rxCanFrame;
CANINFO *canInfoPtr;

int main(void)
{

     u_short base_address = 0x8000;
     NutRegisterDevice(&devSJA1000, base_address, 0);

     // Set CAN bit rate
     CAN_SetSpeed(&devSJA1000, CAN_SPEED_125K);

     // Prepare a sample frame for sending
     memset(&txCanFrame, 0, sizeof(txCanFrame));
     txCanFrame.id = 0x123;
     txCanFrame.len = 8;
     txCanFrame.ext = 0; // Set to 1 to send an extended frame
     txCanFrame.byte[0] = 0x11;
     txCanFrame.byte[1] = 0x22;
     txCanFrame.byte[2] = 0x33;
     txCanFrame.byte[3] = 0x44;
     txCanFrame.byte[4] = 0x55;
     txCanFrame.byte[5] = 0x66;
     txCanFrame.byte[6] = 0x77;
     txCanFrame.byte[7] = 0x88;

     while(1)
     {
        CAN_TxFrame(&devSJA1000, &txCanFrame);
	  CAN_RxFrame(&devSJA1000, &rxCanFrame);

     	  txCanFrame.id = rxCanFrame.id;
     	  txCanFrame.len = 8;
     	  txCanFrame.ext = rxCanFrame.ext;
     	  txCanFrame.byte[0] = rxCanFrame.byte[0]+1;
     	  txCanFrame.byte[1] = rxCanFrame.byte[1]+1;
     	  txCanFrame.byte[2] = rxCanFrame.byte[2]+1;
     	  txCanFrame.byte[3] = rxCanFrame.byte[3]+1;
     	  txCanFrame.byte[4] = rxCanFrame.byte[4]+1;
     	  txCanFrame.byte[5] = rxCanFrame.byte[5]+1;
     	  txCanFrame.byte[6] = rxCanFrame.byte[6]+1;
     	  txCanFrame.byte[7] = rxCanFrame.byte[7]+1;


        NutSleep(2000);
     }

     return 0;
}

-- 
Petri