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TMS320F2800137: Cannot set registers when more than 2 SPI slaves (LDC 1101) are connected

Arun Vishwanath
Prodigy 50 points
Part Number: TMS320F2800137


Tool/software:

I am using a TMS320F2800137 LaunchPad and am using SPI to set and control LDC 1101 sensors. Reading and writing to LDC 1101 registers using SPI works when I connect up to 2 LDC 1101 slaves. I am using GPIO pins for STE (i.e. chip select).

But when I connect 3 (or more), writing to a register and reading the data back does not seem to work. In other words, writing a 1 and reading the register back does not return 1.

Is there a limitation on how many SPI devices can be connected to this launchpad or is there something I need to configure when using more than 2 SPI slaves?

Thank you very much for your insights.

  • 0
    TI__Mastermind 24380 points

    Hello,

    Arun Vishwanath said:
    writing to a register and reading the data back does not seem to work. In other words, writing a 1 and reading the register back does not return 1.

    Can you please clarify what register(s) you are referring to here? What is the setup of your testing and what is indicating an error?

    You should be fine with multiple SPI peripheral devices as long as the chip select is handled separately. Are you scoping all of the SPI lines to ensure/confirm your communication and behavior of SPI is as expected?

    Best Regards,

    Allison

  • +1 in reply to Allison Nguyen
    Prodigy 50 points

    I was not initialised the GPIO pins correctly. Setting them all HIGH to begin with and then selecting each peripheral device individually by driving CS low solved the problem. Thanks Allison for your reply.