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Compiler/TDC1000-TDC7200EVM: Changing SPI CLK frequency

Thibault Helle
Expert 2090 points

Part Number: TDC1000-TDC7200EVM

Tool/software: TI C/C++ Compiler

Hi!

I am integrating a RF95 wireless module on the same SPI bus as the TDC1000 and TDC7200 as a slave. The module could only handle max 10MHz of CLK so I needed to divide it by 4 (UCB0BR0) to get 6MHz instead of 12MHz, which worked. 

However I am afraid that it could affect the TOF measurement timings of the TDC1000/7200 communications. What are side affects of slowing CLK down? (using it for flow metering).

I had one idea of changing the frequency depending of which slave that is used, would that be a good idea? If so, do I need to shutdown the SPI bus every time I change it?

Thanks in advance!

Regards,
Thibault 

  • 0
    TI__Mastermind 31655 points
    Hi Thibault,

    The SPI clock is independent of any of the TOF measurement timing. The TOF measurements will not be affected by the speed of the SPI clock. The only thing that will be limited is the maximum frequency of the measurements which are determined by the TOF itself, and the speed with which you can read the time measurement registers from the TDC7200.

    It is not necessary to change the SPI clock frequency dependent on the slave being used.

    Regards,