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TCAN4550-Q1: SPI to CAN

Hangjie Wang
Intellectual 1210 points
Part Number: TCAN4550-Q1
Other Parts Discussed in Thread: TCAN4550

We have one new project, that would use TI DSP(spiclk can reach 12.5M), which is without CAN FD a.
We promote TCAN4550-Q1 as SPI to CAN FD bridge transciver.
The limitation is, for F28034 DSP, the max SPI clock is 12.5MHz max.
Could you help check with 12.5M SPI clock, what’s the CAN FD max data rate could be ? And how to calculate or evaluate ?
Customer is expecting 5Mbps CAN FD, if TCAN4550 could not meet, do you have any other suggestions ?

I understand that the data rate from SPI to CAN FD is satisfied, but the speed from CAN FD to SPI depends on the maximum memory of a single CAN message and the minimum time between two CAN messages

Can you tell me if the SPIclk clock is set to 18M and CAN 5MHz are connected? Or SPICLK18M speed is just a hardware process limitation,

Thanks.

  • 0
    TI__Guru 53555 points

    Hi Hangjie,

    It is certainly possible to achieve 5Mbps CAN rates with a 12.5MHz SPI clock. However, there are a few more variables that dictate this relationship, namely the CAN data payload size (64 bits is best) and CAN arbitration rate. Also important to note are the extra delays on the SPI side for inter-frame spacing and delay between nCS assertions. 

    I've discussed this further with your college via email. I will add you to the email chain so you can see my full response and get access to a helpful tool for these calculations.

    Regards,
    Eric Schott

  • 0 in reply to Eric Schott1
    TI__Intellectual 1210 points

    I have received your email and thank you very much for your support.