hi,
szoshi How does the bela system use the I2S
Actually it doesn't. Not quite. The McASP (multi-channel audio serial port, on the SoC side) and the TLV320AIC3104 codec are both pretty flexible in terms of data format. What we have at the moment is a custom format, but it could be set to work in standard-compliant I2S mode.
szoshi Is an exact freq like 24.576 MHz generated anywhere in the system or does the system work with the 26 MHz that the AM3358 McASP seems to generate?
There is a PLL on the TLV320AIC3104 which can generate an internal BCLK based on a wide range of external voltages. The McASP can provide a 24MHz clock, optionally routed through a divider. We send 12MHz to the codec which then generates bit clock and frame clock.
Hope the above puts you on the right track, there are some more details in the actual code. I shall also let you know that at Bela we do consultancy work to tailor our software and hardware to the customer's needs. If that is of interest to you - now or in the future - do not hesitate to contact us at info@bela.io.