• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 80 subscribers
  • Views 216 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

Testing CAN output without transciever

TMS320F280049: CAN bus Problem on TMS320F280049

Richard Robinson
Intellectual 720 points
Part Number: TMS320F280049
Other Parts Discussed in Thread: SYSBIOS

Hi,

I have an interesting problem with the CAN controller on a F280049. I am using CAN controller 'A' connected using GPIO32 and GPIO18. Using the CAN controller without loopback I get no data from GPIO32/CANA_TX, however if I enable external loopback I can receive CAN messages externally on the PC using PCAN Explorer. I have checked the mux configuration for both GPIO18 and GPIO32 by looking directly at the mux registers and they are correctly configured. Given this information I know the following 

1) Bit rate configuration is correct.

2) my code is sending packets and I can receive the packets correctly. Therefore the transmit path up to and including the CAN transceiver is working correctly.

Here is my test code I am using SYSBIOS but I believe this not to be relevant to this issue. 

//CANA -> CAN0 Pinmux
GPIO_setPinConfig(GPIO_18_CANA_RX);
GPIO_setPinConfig(GPIO_32_CANA_TX);

//CAN0 initialization
CAN_initModule(CANA_BASE);

// Enable CAN test mode
CAN_enableTestMode(CANA_BASE, CAN_TEST_EXL);

// Refer to the Driver Library User Guide for information on how to set
// tighter timing control. Additionally, consult the device data sheet
// for more information about the CAN module clocking.
//
CAN_setBitRate(CANA_BASE, DEVICE_SYSCLK_FREQ, 125000, 10);

//
// Enable interrupts on the CAN peripheral.
//
CAN_enableInterrupt(CANA_BASE, CAN_INT_IE0 | CAN_INT_ERROR |
CAN_INT_STATUS);
//
// Enable the CAN interrupt signal
//
CAN_enableGlobalInterrupt(CANA_BASE, CAN_GLOBAL_INT_CANINT0);

//
// Enable auto-retry on CAN transmit.
//
CAN_enableRetry(CANA_BASE);

//
// Configure the message objects that are based on the device number.
//
CANDeviceNumSet(CAN_DEVNO_RMTPHS);

//
// Start CAN module A operations
//
CAN_startModule(CANA_BASE);

Any help would be appreciated.

Thanks,

Richard.

  • 0
    Intellectual 720 points

    Hi,

    Well I figured out what the problem is, you cannot use GPIO18 when you are using X1 as a clock input. That does raise the question as to why you would put a CAN bus signal on a pin that cannot be used when you have a clock connected, as you need the clock for correct CAN bus timing! I guess the moral of the story is read the whole datasheet!

    Thanks,

    Richard.