Nucleo-H743ZI No data out in I2S slave mode

[savvn001]

HI, I'm trying to interface this board to a cirrus logic CS42448 codec. I set up the I2S3 peripheral in slave mode configured in CubeMX as so:

The project is built with this and in the main while loop I have a simple bit of code to get it to transmit some random data:

 /* Infinite loop */

 /* USER CODE BEGIN WHILE */

bool channel = false;

uint16_t data_test[2] = { 0x0324, 0x0000};

while (1) {

 /* USER CODE END WHILE */

 /* USER CODE BEGIN 3 */

if (HAL_I2S_GetState(&hi2s3) == HAL_I2S_STATE_READY) {

HAL_I2S_Transmit(&hi2s3, &data_test[channel], 1, 0);

channel = !channel;

}

}

 /* USER CODE END 3 */

}

The codec is providing the LR/WS clock and bit clock and I have it running at a sample rate of 32kHz (my logic analyser has limited bandwith). I can verify however that the clocks are coming in at the right frequencies with my logic analyser, however there isn't any data coming out of the board.

When I re-configure the board in I2S master mode however and disconnect the codec, with the exact same settings and code I can see there is data coming out.

Thanks!

[waclawek.jan]

From RM0433, 50.9.2 Pin sharing with SPI function:

> SDO: Serial Data Output (mapped on the MOSI pin) to transmit the audio samples in

> master, and to receive the audio sample in slave.

You can try to set SPI_CFG2.IOSWP.

I am not sure about what  Serial data line swapping table indicates, IMO it contradicts the narrative I quoted above.

Disclaimer, I don't use the 'H7.

JW

[savvn001]

Hi, thanks for the response, I've tried that but it's not making a difference. I've got probes on the input and output pins so I would see if something comes out of either

[waclawek.jan]

As I've said I don't use 'H7, and the SPI/I2S on that is different from the other STM32 families, so can't help with that, sorry.

JW

[savvn001]

Has anyone else managed to get I2S working on the STM32H7? Hit a bit of a brick wall here with this one, as there isn't any example projects at all for I2S or even SAI with the H743.