I2S - Audio Samples and data type

[Dave_PL]

Hi,

I would like to generate some test audio signals like sine wave for testing codecs. But there is a problem because I do not know how the data is presented. Is it just simple Linear PCM? Then for example maximum amplitude (i.e. 1) of my sine wave would be 11111111 (if 8 bit data) and minimum amplitude (i.e. -1) is 00000000. Or is it 2s complement? So then maximum (1) is 01111111 and minimum (-1) is 10000000.

Regards,
Dave

 

[trav1s]

Yes, it is PCM. It is not two's complement. 00000000 is the minimum and 11111111 is the maximum.

 

[Dave_PL]

So why in I2S spec is written: "Serial data is transmitted in two's complement with the MSB first" ?

 

[trav1s]

So try it. If it doesn't work try the other way. The worst that could happen is you don't get a sine wave input, but this should be pretty easy to verify. Its not going to break just because the input isn't a pure tone.