AnsweredAssumed Answered

DMA does not work properly with LPC4088 (QSB)

Question asked by shogo matsubara on Dec 20, 2019
Latest reply on Dec 27, 2019 by Felipe García

LPC4088 QSB is used.

I want to acquire 128 samples each using DMA at a sampling rate of 16kHz.


I have two problems now.


Problem 1:

1kHz analog input is A / D converted and acquired by DMA.A clean waveform can be obtained when the ADC rate is set to 400 kHz, but if the rate is set to 1 kHz, the waveform will be very noisy.

This does not happen when polling and interrupts are used.


Problem 2:

When the DMA transfer size is set to 1 and 128, etc., the waveform obtained by DMA is different even if the same analog waveform is input.


(D / C conversion and seeing waveform with oscilloscope)


The source code uses periph_adc of the following sample code.


Thank you.

lpc4088 qsb lpcxpresso lpc4088