I'm attempting to use I2S to drive the WM8978 for audio recording (the SAI pins are already occupied, so please don't suggest switching to SAI). I've ported the well-tested WM8978 driver code from the F4 series and configured I2S DMA to receive data. However, I haven't been able to receive audio data—there's only clean background noise. I've tested the waveforms at the I2S interface, and here's how I've configured I2S in my code:
<i2s config>
hi2s3.Instance = SPI3;
hi2s3.Init.Mode = I2S_MODE_MASTER_RX;
hi2s3.Init.Standard = I2S_STANDARD_PCM_SHORT;//I2S_STANDARD_PHILIPS;
hi2s3.Init.DataFormat = I2S_DATAFORMAT_16B;
hi2s3.Init.MCLKOutput = I2S_MCLKOUTPUT_ENABLE;
hi2s3.Init.AudioFreq = I2S_AUDIOFREQ_8K;
hi2s3.Init.CPOL = I2S_CPOL_LOW;
hi2s3.Init.FirstBit = I2S_FIRSTBIT_MSB;
hi2s3.Init.WSInversion = I2S_WS_INVERSION_DISABLE;
hi2s3.Init.Data24BitAlignment = I2S_DATA_24BIT_ALIGNMENT_RIGHT;
hi2s3.Init.MasterKeepIOState = I2S_MASTER_KEEP_IO_STATE_DISABLE;
<wm8978 config>
bsp_InitI2C();
wm8978_Init();
WM8978_ADDA_Cfg(0,1);
WM8978_Input_Cfg(1,0,0);
WM8978_Output_Cfg(0,1);
WM8978_MIC_Gain(46);
WM8978_LINEIN_Gain(5);
WM8978_I2S_Cfg(3,0);//PCM Format
MX_I2S3_Init();
<Callback>
void HAL_I2S_RxCpltCallback(I2S_HandleTypeDef *hi2s)
{
if(hi2s->Instance == SPI3)
{
current_buf_flag = pcm_buf_flag;
pcm_buf_flag = !pcm_buf_flag;
HAL_I2S_Receive_DMA(&hi2s3, pcm_data[pcm_buf_flag], PCM_SIZE/2);
AsrEventFlag = true;
}
}
<main while>
while (1)
{
if(AsrEventFlag)
{
AsrEventFlag = false;
HAL_GPIO_TogglePin(GPIOE,GPIO_PIN_2);
HAL_UART_Transmit_IT(&huart5,(uint8_t*)pcm_data[current_buf_flag],PCM_SIZE);
}
}
The measured MCLK is 1.024 MHz, and WS, SCK, and SDI are all around 8 kHz, but I still can't receive audio data correctly. Why aren't there any I2S examples for the H7? Can someone who has used the H7's I2S interface help me out?
