LPC4088 QSB is used.
I want to acquire 128 samples each using DMA at a sampling rate of 16kHz.
I have two problems now.
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.
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.