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I2S on STM32F0

Question asked by Luke on Mar 1, 2016
Latest reply on Mar 1, 2016 by Luke
So I am trying to output an I2S signal from a STM32F0 but although I believe I am initializing the peripheral correctly I am not getting any signal on the pins. I believe I am enabling the appropriate clocks and have the pin/DMA mapping correct based on the information I have. What am I missing? My code is as follows:

     I2S_InitTypeDef I2S_InitStructure;
     GPIO_InitTypeDef GPIO_InitStructure;
     DMA_InitTypeDef DMA_InitStructure;

     audio[0] = 0x5555;
     audio[1] = 0x0;
     audio[2] = 0x5555;
     audio[3] = 0x0;
     audio[4] = 0x5555;
     audio[5] = 0xffff;
     audio[6] = 0xffff;
     audio[7] = 0xffff;
     audio[8] = 0xffff;
     audio[9] = 0xffff;

     RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE); 
     GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4 | GPIO_Pin_5 | GPIO_Pin_7;
     GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
     GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
     GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
     GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
     GPIO_Init(GPIOA, &GPIO_InitStructure);
     GPIO_PinAFConfig(GPIOA, GPIO_PinSource4, GPIO_AF_0);  // I2S1 WS (word select)
     GPIO_PinAFConfig(GPIOA, GPIO_PinSource5, GPIO_AF_0);  // I2S1 CK (serial clock)
     GPIO_PinAFConfig(GPIOA, GPIO_PinSource7, GPIO_AF_0);  // I2S1 SD (serial data)

     // I2S1 peripheral configuration
     RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1, ENABLE);
     I2S_InitStructure.I2S_Standard    = I2S_Standard_Phillips;
     I2S_InitStructure.I2S_DataFormat  = I2S_DataFormat_16b;//32b;//24b;
     I2S_InitStructure.I2S_AudioFreq   = I2S_AudioFreq_8k;
     I2S_InitStructure.I2S_CPOL        = I2S_CPOL_Low;
     I2S_InitStructure.I2S_MCLKOutput  = I2S_MCLKOutput_Enable;//Disable;//
     I2S_InitStructure.I2S_Mode        = I2S_Mode_MasterTx;
     I2S_Init(SPI1, &I2S_InitStructure);

     // DMA configuration for audio streaming
     RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);
     DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;
     DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&SPI1->DR;  // SPI data register for sending
     DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)audio;
     DMA_InitStructure.DMA_BufferSize = 10;
     DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
     DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
     DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
     DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
     DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
     DMA_InitStructure.DMA_Priority = DMA_Priority_High;
     DMA_Init(DMA1_Channel3, &DMA_InitStructure);
     SPI_I2S_DMACmd(SPI1, SPI_I2S_DMAReq_Tx, ENABLE);

     DMA_Cmd(DMA1_Channel3, ENABLE);                   // Enable/Disable DMA
     I2S_Cmd(SPI1, ENABLE);

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