TMS570LS1224: CAN example doubt

Sakthi Sundaram

Part Number: TMS570LS1224
Other Parts Discussed in Thread: LAUNCHXL2-TMS57012

I have implemented the CAN example code in LAUNCHXL2-TMS57012 board. The messages transfer from CAN1 to CAN2. I had put a breakpoint at the line "while(1);", to view the output of CAN1 and CAN2 registers. But, I am not able to figure out the registers on the variables screen (CCS debug mode) . However, In SPI loopback mode i was able to view the messages there.

Please tell me how do i check whether am i sending the right message and is the message get received on CAN2.

code:

/* USER CODE BEGIN (0) */
/* USER CODE END */
/* Include Files */
#include "sys_common.h"
#include "system.h"
/* USER CODE BEGIN (1) */
#include "can.h"
/* Include ESM header file - types, definitions and function declarations for system driver */
#include "esm.h"
#define D_SIZE 9
uint8 tx_data[D_SIZE] = {'H','E','R','C','U','L','E','S','\0'};
uint8 rx_data[D_SIZE] = {0};
uint32 error = 0;
uint32 checkPackets(uint8 *src_packet,uint8 *dst_packet,uint32 psize);
/* USER CODE END */
/* USER CODE BEGIN (2) */
/* USER CODE END */
void main(void)
{
/* USER CODE BEGIN (3) */
/* initialize can 1 and 2 */
canInit(); /* can1 -> can2 */
/* transmit on can1 */
canTransmit(canREG1, canMESSAGE_BOX1, tx_data);
/*... wait until message receive on can2 */
while(!canIsRxMessageArrived(canREG2, canMESSAGE_BOX1));
canGetData(canREG2, canMESSAGE_BOX1, rx_data); /* receive on can2 */
/* check received data patterns */
error = checkPackets(&tx_data[0],&rx_data[0],D_SIZE);
/* ... run forever */
while(1);
/* USER CODE END */
}
/* USER CODE BEGIN (4) */
uint32 checkPackets(uint8 *src_packet,uint8 *dst_packet,uint32 psize)
{
uint32 err=0;
uint32 cnt=psize;
while(cnt--)
{
if((*src_packet++) != (*dst_packet++))
{
err++; /* data error */
}
}
return (err);
}
/* USER CODE END */

over 4 years ago

0 QJ Wang over 4 years ago

TI__Guru**** 197036 points

Hello,

You can check the rx_data in CCS memory browser, and check IF2DAT to see if the received data has been transferred to IF data register.

0 Sakthi Sundaram over 4 years ago in reply to QJ Wang

Intellectual 280 points

I have connected directly one physical wire between J10 connector pin 12 (CAN2_RX) and J10 connector pin 39 (CAN1_TX) in my LAUNCHXL2-TMS57012 board and 120ohm resistances aren't present in my launchpad .

In TX of CAN1 memory I am able to see the data but RX memory of CAN2 doesn't have any data.

DSP launchpad is connected and debug is completed. I have removed the breakpoint from my code.

Can I please know why I am not getting any data in CAN2 RX memory?

where am i going wrong ?

+1 QJ Wang over 4 years ago in reply to Sakthi Sundaram

TI__Guru**** 197036 points

You can not connect CAN1 TX to CAN RX for communication. For CAN bus communication, normally the CAN transceiver is required for a CAN node. The CAN_H and CAN_L must be terminated. You should use 120 ohms resistors for termination. If you place multiple devices on the CAN network, only the devices on the ends of the network need termination resistors.

If the cable between CAN nodes is very short, you can use non-transceiver way for CAN communication. Please refer to this application:

https://www.mikrocontroller.net/attachment/28831/siemens_AP2921.pdf

0 Sakthi Sundaram over 4 years ago in reply to QJ Wang

Intellectual 280 points

CAN node 1 TX -> CAN node 2 RX

CAN node 1 RX -> CAN node 2 TX

This is valid connection right ?

I am testing BTW two CAN node on the same launchpad. Cable length is small.

+1 QJ Wang over 4 years ago in reply to Sakthi Sundaram

TI__Guru**** 197036 points

No, it is not correct. Please see the application note in my previous post.

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TMS570LS1224: CAN example doubt