Generating tone via SAI with imx8 as slave

[abtom87]

I am configuring the SAI pins and enabling external clock like so:

	IOMUXC_SetPinMux(IOMUXC_SAI3_TXFS_SAI3_TX_SYNC, 0U);
	IOMUXC_SetPinMux(IOMUXC_SAI3_TXC_SAI3_TX_BCLK, 0U);
	IOMUXC_SetPinMux(IOMUXC_SAI3_TXD_SAI3_TX_DATA0, 0U);
	IOMUXC_SetPinMux(IOMUXC_SAI3_MCLK_SAI3_MCLK, 0U);

	// Set Pin Config
	IOMUXC_SetPinConfig(IOMUXC_SAI3_TXFS_SAI3_TX_SYNC, value);
	IOMUXC_SetPinConfig(IOMUXC_SAI3_TXC_SAI3_TX_BCLK, value);
	IOMUXC_SetPinConfig(IOMUXC_SAI3_TXD_SAI3_TX_DATA0, value);
	IOMUXC_SetPinConfig(IOMUXC_SAI3_MCLK_SAI3_MCLK, value);

	// Enable extern MCLK
	IOMUXC_GPR->GPR[2] |= IOMUXC_GPR_GPR2_GPR_SAI3_EXT_MCLK_EN(1);

Then i create the transfer Tx handle which contains the SAI Tx callback like so:

	SAI_Init(SAI_I2S);
	SAI_TransferTxCreateHandle(SAI_I2S, &saiHandle, sai_tx_callback, saiBuffer);
	saiHandle.bitWidth = 32U;
	saiHandle.channel = 0;
	saiHandle.channelMask = SAI_CHANNEL_MASK;
	saiHandle.channelNums = 2;
	saiHandle.endChannel = 1;

I configure the imx as slave

	sai_fifo_t fifo;
	sai_fifo_packing_t packing;
	packing = kSAI_FifoPacking8bit;
	SAI_TxSetFIFOPacking(SAI_I2S, packing);

	sai_transceiver_t config;
	SAI_GetClassicI2SConfig(&config, SAI_BIT_WIDTH, SAI_MONO_STEREO, SAI_CHANNEL_MASK);
	config.fifo = fifo;
	config.masterSlave = kSAI_Slave;
	config.syncMode = kSAI_ModeAsync;
	config.bitClock.bclkSource = kSAI_BclkSourceMclkOption1;
	SAI_TxSetConfig(SAI_I2S, &config);

Do a fifo reset before preparing my data and sending the data using 

SAI_TxSoftwareReset(SAI_I2S, kSAI_ResetTypeSoftware);
 
	// Prepare transfer
	sai_transfer_t xfer =
	{
		.data = (uint8_t *)saiBuffer,
		.dataSize = sizeof(uint32_t) * SAI_BUFFER_SIZE,
	};

	if ((ret = SAI_TransferSendNonBlocking(SAI_I2S, &saiHandle, &xfer)) == kStatus_Success)
	{
	}
	else 
	{
		//Do some debugging
	}

The weird part is, the interrupt fires, the callback is called and I am printing out the TFR and TDR registers which all show 0x00. What am i doing wrong here? Is EDMA the only way or something else? Any help or pointers would be appreciated!

[Manuel_Salas]

Hello @abtom87 

I hope you are doing very well.

Before to start looking for any code issue, could you please measure the MCLK signal?

I would like to be sure there is the signal in the PAD.

Best regards,

Salas.

[abtom87]

Yes I measured the clock. There is signal. The interrupt wouldnt be fired otherwise or?