TMS320F280049: CAN Port Setup using C2000ware

Todd,

            If you scope the CANTX pin, do you see any activity? Even assuming there is a clock config problem, you should see some activity in the CANTX pin.

Hareesh
Thanks for your reply. I will scope TX. So far, I am getting good response when I connect Pcan to the CAN bus. I have also been able to connect to customer’s app.

Hareesh:
For some reason on F280049 ControlCard, using the external oscillator and resulting SYSCLK as source for CAN did not work, BUT if I sourced external oscillator directly to the CAN, it did work - came up and ran without any problems.

This was highly unusual, because I also have an F2837x ControlCard, and CAN will work with both external oscillator as direct connection and using SYSCLK, with SYSCLK being sourced from external oscillator.

Do you know of any reasons why the F280049 ControlCard needed CAN to be sourced directly from the external oscillator?

Todd,

            I presume you ran the C2000ware example “as is” to start with.

 

Can you confirm you are using the clock path highlighted by the dotted red line in the attachment? I presume you are writing to the CLKSRCCTL2 register to switch the CAN clock source and changing that frequency to 20 MHz.

 

What bit-rate are you using? Does it make a difference if you use a very low bit rate like 50 kbps?

 

By any chance, are you using the 10 MHz internal oscillator (INTOSC)?

Todd,
Any update on this?

Hareesh:
Yes, I am using the path highlighted to supply clock to CAN (20 MHz on ControlCard). And as far as I know, I am using the same 20 MHz clock as an external clock source. However, trying to route the SYSCLK to CAN did not work on my particular ControlCard. I will try another ControlCard that is present here, to see if it exhibits the same problem. The code is based on C2000WARE, but is custom code that was ported from an F2837x ControlCard.

Hareesh:
Here is snippet of the code used. I have commented out the working external clock, and attempted to add 2 lines using internal clock source.

/** - initialize port pins for CAN-A */
GPIO_setPinConfig( GPIO_30_CANRXA );
GPIO_setPinConfig( GPIO_32_CANTXA );

/** - initialize the CAN controller, select SYSCLK source and set 500 kbps */
CAN_initModule( CANA_BASE );

/* This is an attempt to use internal clock source - does not work. */
CAN_selectClockSource( CANA_BASE, CAN_CLOCK_SOURCE_SYS );
CAN_setBitRate(CANA_BASE, 100000000, 1000000, 16);

/* Below two lines are code that does work -
CAN_EXT_CLK is 20,000,000, CAN_BIT_RATE is 500,000, CAN_BIT_TIME is set to 20

CAN_selectClockSource( CANA_BASE, CAN_CLOCK_SOURCE_XTAL );
CAN_setBitRate( CANA_BASE, CAN_EXT_CLK, CAN_BIT_RATE, CAN_BIT_TIME );
*/
CAN_setAutoBusOnTime( CANA_BASE, ABO_DELAY_SEC * HZ_PER_MHZ * SYSCLK_MHZ );
CAN_enableAutoBusOn( CANA_BASE );

/** - wait for broadcast from downloader */
vConfigRxMailboxes( BROADCAST_ID, MODE_NORMAL );

/** - start CAN module A operation */
CAN_startModule( CANA_BASE );