PDM decoding on PC

Using logic analyzer to grab PDM data

• Acquire PDM data using a Logic Analyzer and export the data in ASCII format. End result is a text file containing single rows of zeroes and ones. If using Salae logic analyzer, for example, you can use the "Parallel Decoder". See bellazio.txt.bz2 for a PDM dump file example.
• Convert PDM data in the format suitable for openpdm library, i.e.: packed PDM bits, using 'txt2bin.c' program: bzcat bellazio.txt.bz2 | ./txt2bin > bellazio.dat
• Listen to decoded audio passing PDM sampling frequency (-f option) and decimation factor (-d option) : pdm2pcm -f1024000 -d128 < ./bellazio.dat | aplay -fS16_LE -c1 -r8000
• All in a single line: bzcat bellazio.txt.bz2 | ./txt2bin | ./pdm2pcm -f1024000 -d128 | aplay -fS16_LE -c1 -r8000

Using Cypress FX2LP setup

• Follow instructions provided in the pdmgrabber folder for setting up the hardware.
• Grab up to eight microphones in parallel using fx2grabber utility as follows: fx2grabber -d4 dump.pdm
• Use packdata utility to extract microphone channels and decode them to PCM with: packdata.exe 0 < dump.pdm | pdm2pcm -f 2048000 -d128 | aplay -fS16_LE -c1 -r16000 where '0' is the index of the microphone to extract.