Audio rate sampling on lpc1343

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by RPrice on Mon Nov 05 09:07:33 MST 2012

  I'm doing audio rate sampling on the lpc1343, I have a piece of test code that samples the input and sends it back out unaltered to a DAC connected by SPI. It works fairly well but I have quiet high frequency whine that I think is due to sampling noise on the input, it looks like a square wave on the output even when I'm sampling silence (input flat at 1.5 v).

  I think the internal capacitor on the ADC isn't charging quick enough and is the source of the noise. This points to a source impedance problem on my circuit.

  My question is has anyone had any success sampling at 22khz at the full 12 bit resolution offered by the lpc1343?