Audio signal recording with ADC and DMA

[martinlorenz]

Hello,

I have a LPCxpresso1549 board and I'm new to LPC MCUs.

I'm desperately looking for a tutorial / code example / application note which shows how to capture an audio or other signal (mono or several channels) with a given sample rate and a given numer of samples corresponding to a certain duration.

It would be great if the ADC is coupled with DMA so that the captured signal is stored in a given SRAM array in the background without any CPU load.

Perhaps the whole recording process can be controlled and triggered by a SCT in the background?

My use case:

The LPC1549 has two fast ADCs with 2 MSample/s and I want to record a mono and stereo signals with at least 500kS/s, so this should be easily possible. I need to sample 1024 points and want to do a FFT and other signal processing afterwards.

I'm pretty shure that thousands of engineers have the same or similar use case, so please, dear NXP support, provide us with an example or application note on this topic

[ianbenton]

Easy enough to make the ADC sample at any given frequency just by setting Burst (bit 27) in the SEQA control register so that it runs continuously, and then choosing a value for CLKDIV (bits 0:7 of CTRL) so that it runs at the required speed, but why such a high sample rate? A 1024 point FFT at 500kSamples/second isn't going to show anything below 500Hz.

[martinlorenz]

Why such a high sample rate?

Off course we don't have an ordinary audio application.

But we want to measure ultrasonic signals at frequencies far above 20kHz.

And therefore we need such high sample rates!

[martinlorenz]

Do NXP people read this forum?

I would be glad to hear a comment from them.

[vicentegomez]

Hi

there is not a sample like you need but you can check all the samples on the

LPCOpen Software Development Platform LPC15XX​

I hope this will help you.

Regards

Vicente Gomez

[lpcware]

bump