Having trouble getting adc values with dma

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Having trouble getting adc values with dma

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Muhammet
Contributor I

I am using MPC5744P and having trouble getting ADC values with DMA. I am using hardware trigger for DMA and using the scan continuous method for ADC. When I looked at the buffer in RAM realized that there are repetitive and non-valid values in the buffer. I researched RM to mask non-valid values but unfortunately, I could not find anything about it. How should I follow so that non-valid values are not written to the buffer?

 

exp_of_adc_prob.png

1 Reply

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petervlna
NXP Employee
NXP Employee

Hello,

That's pretty hard to tell from one screenshot of array.

Basically DMA after each HW conversion from ADC clears the valid bit by acknowledging it.

It really depends on how you set DMA (its not so simple). So, first try to successfully transfer 1 ADC results via one DMA channel. Once you get that working you can start play with target address adjustment etc... in DMA.

DMA is only dummy HW, so all you need to do is to set it correctly.

Best regards,

Peter

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