I2S Peripheral - Disable slot swapping?

[AnkhInnovationsLLC]

Hello,

Is there a way to disable the slot swapping of the I2S peripheral?

Take the following example, without any HAL_I2S callbacks...

 

void start_loopback(I2S_HandleTypeDef* is2_handle) {
	printf("--> Starting algorithm loop back...\n");

	for (int i=0; i<I2S_FRAME_SAMPLES; i++){
		i2sTxBuffer[i] = i;
	}

	int hal_res = HAL_I2SEx_TransmitReceive_DMA(is2_handle, i2sTxBuffer, i2sRxBuffer, I2S_FRAME_SAMPLES);
	if(hal_res != HAL_OK) {printf("I2S - HAL_I2SEx_TransmitReceive failed, hal_res = %d!\r\n", hal_res); HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_0);}

	while(1){
		vTaskDelay(100);
	}

 

 It unexpectedly produces the following on the receiving end:

 

1 0 3 2 5 4 7 6 9 8 11 10 13 12 15 14 17 16 19 18 21 20 23 22 25 24 27 26 29 28 31 30 

 

 

As I'm consuming and producing I2S samples in software, there is no need for the swap, the DMA buffer will already be in an appropriate format to send over the I2S wire.

[LCE]

That looks like some DMA buffer / width mismatch.

Start simple, set all to WORD / 32 bit.

[AnkhInnovationsLLC]

So this ended up being on the receiver side of things, the ESP32:

https://www.esp32.com/viewtopic.php?t=11023

Thanks!