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DMA / SPI with GPIO trigger on K64

Question asked by Mikael Elharrar on Oct 7, 2017
Latest reply on Oct 18, 2017 by Mark Butcher

Hi Community,


It is the fifth post I write on this subject (DMA/SPI/GPIO trigger) and I didn't yet succeeded to close my issue.


I have an external ADC ( ADS121A02 from TI ) connected through SPI0 to my K64 microcontroller.


On this ADC, each time the both channels are ready to be read ( ADC is configured as slave and K64 as master), a GPIO pin ( called NRDY ) is asserted to logical level 0.


In order to not disturb the microcontroller each time a new sample is ready ( I have to reach 48KSample / sec), I would like to trigger the DMA automatically and get an interrupt each 32 new samples.


Each new sample, the SPI should output 12 bytes (4 bytes status, and 2 channels x 4 bytes each).


I configured the SPI TX to be triggered by the GPIO, and SPI Rx to pick an interrupt each 32 samples.


Unfortunately, when I configure my DMA to be triggered by an external GPIO, the SPI doesnt output any signal ....

I checked with a scope, and SCK/MOSI and  MISO are not performing the transfer at all, BUT the internal counter of the DMA was decreased (as expected).


I publish here my code. If someone can help / tell me what is wrong into it, it will be very nice.


It done with KDS.


Thank you all

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