TCAN4550-Q1: How do enable internal loop back or external loopback mode

QJ Wang

Guru**** 197336 points

Part Number: TCAN4550-Q1
Other Parts Discussed in Thread: TCAN4550

Hello Expert,

TCAN4550 has two kind of loop back modes for diagnostic test. Setting LBCK bit (bit 4 of test register) will enable the loop back mode. Is there a bit to enable internal loop back and external loop back?

If loop back (internal or external) is enabled, I write data to TX fifo and transmit, I will get the same data in RX FIFO, is that correct?

over 6 years ago

0 Miguel Robertson over 6 years ago

TI__Guru 62920 points

Hi QJ,

We are looking into this one too. It is taking a little longer due to having people out of the office.

Max

0 Eric Hackett over 6 years ago

TI__Guru 74292 points

QJ,

You are correct in that setting LBCK bit enables the loopback mode. To set external loopback mode, you must set bit 5 in the CCCR register (0x1018) to 0, and for internal loopback mode you set bit 5 in the CCCR register to 1.

And yes, that is correct. In loopback mode, the M_CAN treats its own transsmitted messages as received messages and stores them into an RX buffer or an RX FIFO.

Please let me know if you have any other questions or concerns.

Regards,

0 QJ Wang over 6 years ago in reply to Eric Hackett

TI__Guru**** 197336 points

Thanks Eric. You answered my question. I noticed that Max gave me the answer last year. Thank you all!

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TCAN4550-Q1: How do enable internal loop back or external loopback mode