Basically there is a master I2S interface I2S0, and a slave interface I2S1. They share the same GPIO pins so I2S1 can slave off of I2S0 if you want, though not sure why you would use this. Each I2S module has 4 bidirectional ports SDI[0-3] and SDO[0-3], sharing the same pins.
I assume the third interface is for the PDM microphone inputs, but that uses SDO[2], SDO[3] and SDI[3] GPIOs so obviously you lose some I2S functionality.
To be quite honest, adding $1 RP2350s to implement as many I2S or TDM ports as you want and passing processed data into the CM5 can be an attractive option as you can use separate clocks and syncs as desired. This works well for one of our products and we downgraded to a cheaper CM4 as it had more than enough computing power but obviously that depends on your application.
I assume the third interface is for the PDM microphone inputs, but that uses SDO[2], SDO[3] and SDI[3] GPIOs so obviously you lose some I2S functionality.
To be quite honest, adding $1 RP2350s to implement as many I2S or TDM ports as you want and passing processed data into the CM5 can be an attractive option as you can use separate clocks and syncs as desired. This works well for one of our products and we downgraded to a cheaper CM4 as it had more than enough computing power but obviously that depends on your application.
Statistics: Posted by MikeDB — Wed Nov 26, 2025 11:58 pm