TMDS64GPEVM: Enabling external CAN send/receive & setting baud rate

Daniel Rakowski

Part Number: TMDS64GPEVM
Other Parts Discussed in Thread: SYSCONFIG

I'm working with the example project mcan_loopback_polling_am64x-evm_r5fss0-0_nortos_ti-arm-clang, and I've configured it to use external CAN by setting internal loopback to FALSE in the call to App_mcanConfig. I added a second MCAN device in SysConfig to allow it to use both physical controllers. I changed the source code such that the messages are transmitted on MCAN0 and received on MCAN1, and that works perfectly (verified by connecting to a second computer with a CAN monitoring utility to verify that the messages were indeed send on the "real" bus).

Now I'd like to set up each CAN channel such that it's possible to send AND receive on one channel instead of sending on one and receiving on the other.

When I attempt to send and receive on the same channel over external CAN, the application stops after transmitting the first burst of 5 messages (that is, it doesn't get to the section of code in mcan_loopback_polling_main where the messages are pulled from the receive queue and contents are verified).

Secondly, I'd like some guidance on setting baud rate. I understand that the default is 1Mpbs, but I can't figure out which parameter(s) I should change to switch to 500kbps or 250kbps.

Thanks for your assistance!

over 4 years ago

0 Frank Livingston over 4 years ago

TI__Mastermind 30118 points

Hi Daniel,

I'm looking into this issue and will get back with you soon.

Regards,
Frank

0 Frank Livingston over 4 years ago

TI__Mastermind 30118 points

Hi Daniel,

Daniel Rakowski said:
Now I'd like to set up each CAN channel such that it's possible to send AND receive on one channel instead of sending on one and receiving on the other.

There is an external loopback example, please see:

https://software-dl.ti.com/mcu-plus-sdk/esd/AM64X/08_01_00_36/exports/docs/api_guide_am64x/EXAMPLES_DRIVERS_MCAN_EXTERNAL_LOOPBACK_INTERRUPT.html
<SDK>\examples\drivers\mcan\mcan_external_loopback_interrupt

In this example:

mcan_external_loopback_interrupt_am64x-evm_r5fss0-1_nortos_ti-arm-clang uses MCAN1 for transmit.
mcan_external_loopback_interrupt_am64x-evm_r5fss0-0_freertos_ti-arm-clang uses MCAN0 for receive.

The other digital (internal) loopback examples in the SDK (like the one you mention) configure a MCAN1 for transmit and receive.

Using these examples, it seems like it should be possible to develop another example with supports simultaneous external (using the TCAN1042HGVD tranceiver) transmit and receive on a single MCAN.

Daniel Rakowski said:
Secondly, I'd like some guidance on setting baud rate. I understand that the default is 1Mpbs, but I can't figure out which parameter(s) I should change to switch to 500kbps or 250kbps.

Inspecting mcan_loopback_interrupt_am64x-evm_r5fss0-0_freertos_ti-arm-clang, I see these MCAN driver API calls:

            mcan_loopback_interrupt_main()
                App_mcanConfig()
                    MCAN_initSetBitTimeParams()
                    MCAN_setBitTime()

It appears the final two APIs are used for configuring the baud rate.

API descriptions are provided here:

MCAN_setBitTime() writes the MCAN hardware module registers.

Details on the MCAN hardware module can be located in the AM64x TRM (spruim2c.pdf), 12.4.1 Modular Controller Area Network (MCAN).

Regards,
Frank

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TMDS64GPEVM: Enabling external CAN send/receive & setting baud rate