RTOS/CC1350: SPI Master/Slave driver example not working with SPI_POL0_PHA0 mode

Tim Simerly

Genius 10075 points

Part Number: CC1350

Tool/software: TI-RTOS

Dear Support:

I am checking out the SPI slave driver and cannot get it to work when setting the following:

spiParams.frameFormat = SPI_POL0_PHA0

however it does work with the example that comes in the driver as:

spiParams.frameFormat = SPI_POL0_PHA1

I am using SDK v2.20.0.38. I have setup 2 different CC1350 boards and running the spimaster and spislave driver examples which is setup in the SDK for SPI_POL0_PHA1 and it runs fine with no issues. However when changing the master and slave code to use SPI_POL0_PHA0, there is no output from the master or slave - the slave callback function is never called and hence no result. Is there something wrong with running the SPI slave in SPI_POL0_PHA0 mode? Or possibly something I am doing wrong? Please advise.

BTW - the master outputs the proper output when running in either SPI_POL0_PHA0 or SPI_POL0_PHA1, it's just the slave that is exhibiting the problem when running with SPI_POL0_PHA0.

Thanks,
Tim

over 7 years ago

0 IUsedToBeARealPerson (M-W) over 7 years ago

TI__Guru 58425 points

Hi Tim,

I'm looking into this, I'll let you know as soon as I have a answer for you!

0 IUsedToBeARealPerson (M-W) over 7 years ago in reply to IUsedToBeARealPerson (M-W)

TI__Guru 58425 points

Hi Tim,

This is behavior is expected. The reason is that when using the SPI_POl0_PHA0 mode, the SPI master hardware requires the mater to toggle the FSS (chip select) pin between each transferred word. In any other frame format, you would be OK as this example implements a 3-wire SPI per default.

If you want to use the SPI_POL0_PHA0 frame format, you will need to also assign and connect a chip select pin for the SPI driver in the board file.

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RTOS/CC1350: SPI Master/Slave driver example not working with SPI_POL0_PHA0 mode