Compatibility with Audio Injector and Cortex M4 usage on STM32MP157D-DK1

[JMart.13]

Hi,

We have acquired this board called Audio Injector (in the image) that has a WM8731, it is a raspberry pi hat, but we want to use it with the STM32MP157D-DK1 but the drivers we have found on the internet seems to be not compatible with this board (we are using the base OpenSTLinux), despite the board has the pinout of raspberry. Someone has used it before? 

Another question, how can we manipulate the Cortex M4 from the Operating system? there is a way we can use it capabilities from the OS? because we noticed that for the Cortex A7 we cannot use the SAI ports as I2S but from the Cortex M4 is possible to use them as I2S. (we saw that on the STM32Cube IDE and CubeMX).

Thanks for your answer.

[PatrickF · Accepted solution]

Hi,

regarding driver, I cannot help much. For information, we are successfully using WM8994ECS on STM32MP157F-EV1 board.

On Cortex-A7, you could certainly use SAI in I2S mode (see https://wiki.st.com/stm32mpu/wiki/SAI_device_tree_configuration), I guess this is the mode we use on our boards (e.g. with Cirrus CS42L51 on the STM32MP157D-DK1 you have).

Regarding pinout compatibility between this board and STM32MP157D-DK1, you should check signals location in the relevant documentations.

Note that SAI2 is available on the 40 pins connector, but it is the same port used with internal CS42L51 codec, so you need to change some 0 ohms (see SB1 to SB4 ans SB13 to SB16) to have it present on 40 pins connector.

Regards.