Question
Not able to read data from SPI2 Interface on STM32F4 board
Posted on March 03, 2018 at 14:46
Hi
I would like to get suggestions and recommendations about this issue. I can see on Scope that my SPI Slave device ADS7959 (ADC) is talking back over SPI but when I debug my code and check the data read is always zero when it should be something different.
My code for setting up the SPI2 and Pins is the following:
GPIO_StructInit(&GPIO_InitStructure);
GPIO_InitStructure.GPIO_Pin = (GPIO_Pin_13 | GPIO_Pin_15); GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL; GPIO_Init(GPIOB, &GPIO_InitStructure); //!< @pinSetup PB13: SPI2_SCK, PB15: SPI2_MOSI GPIO setup GPIO_StructInit(&GPIO_InitStructure); GPIO_InitStructure.GPIO_Pin = GPIO_Pin_14; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL; GPIO_Init(GPIOB, &GPIO_InitStructure); //!< @pinSetup PB14: SPI2_MISO GPIO setup // connect SPIx pins to SPI alternate function GPIO_PinAFConfig(GPIOB, GPIO_PinSource15, GPIO_AF_SPI2); //!< @pinSetup PB15: SPI2_MOSI AF setup GPIO_PinAFConfig(GPIOB, GPIO_PinSource14, GPIO_AF_SPI2); //!< @pinSetup PB14: SPI2_MISO AF setup GPIO_PinAFConfig(GPIOB, GPIO_PinSource13, GPIO_AF_SPI2); //!< @pinSetup PB13: SPI2_SCK AF setupRCC->APB1RSTR |= RCC_APB1RSTR_SPI2RST;
RCC->APB1RSTR &= ~RCC_APB1RSTR_SPI2RST; RCC_APB1PeriphClockCmd(RCC_APB1Periph_SPI2, ENABLE); SPI_InitTypeDef SPI_InitStruct; SPI_InitStruct.SPI_Direction = SPI_Direction_2Lines_FullDuplex; // set to full duplex mode, seperate MOSI and MISO lines SPI_InitStruct.SPI_Mode = SPI_Mode_Master; // transmit in master mode, NSS pin has to be always high SPI_InitStruct.SPI_DataSize = SPI_DataSize_16b; // one packet of data is 8 bits wide SPI_InitStruct.SPI_CPOL = SPI_CPOL_Low; // clock is low when idle SPI_InitStruct.SPI_CPHA = SPI_CPHA_1Edge; // data sampled at first edge SPI_InitStruct.SPI_NSS = SPI_NSS_Soft;// | SPI_NSSInternalSoft_Set; // set the NSS management to internal and pull internal NSS high SPI_InitStruct.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_32; // see freq notes above SPI_InitStruct.SPI_FirstBit = SPI_FirstBit_MSB;// data is transmitted MSB first SPI_InitStruct.SPI_CRCPolynomial = 0x07; // arbitrary (not using), just can't be <= 1 or fails init with ASSERT() SPI_Init(SPI2, &SPI_InitStruct); SPI2->CR1 &= (uint16_t)~((uint16_t)SPI_CR1_CRCEN); // enable SPI peripheral SPI_Cmd(SPI2, ENABLE);To write and read data to/from SPI:
uint16_t AuxAdc::writeWord(uint16_t word)
{ ASSERT_AUXADC_CS; for( uint32_t i = 0; i<firstClockWait; i++ ){asm('nop');} // see timing notes in header SPI2->DR = word; // write data to be transmitted to the SPI data register uint32_t timeout = 0; while( !(SPI2->SR & SPI_I2S_FLAG_TXE) ) // wait until transmit complete { if( timeout++ > 50000 ) { RELEASE_AUXADC_CS; return 0; //!< @TODO RG: need to report this } } timeout = 0; while( !(SPI2->SR & SPI_I2S_FLAG_RXNE) ) // wait until receive complete { if( timeout++ > 50000 ) { RELEASE_AUXADC_CS; return 0; //!< @TODO RG: need to report this } } timeout = 0; while( SPI2->SR & SPI_I2S_FLAG_BSY ) // wait until SPI is not busy anymore { if( timeout++ > 50000 ) { RELEASE_AUXADC_CS; return 0; //!< @TODO RG: need to report this } } for( uint32_t i = 0; i<lastClockWait; i++ ){asm('nop');} // see timing notes in header RELEASE_AUXADC_CS; for( uint32_t i = 0; i<postWait; i++ ){asm('nop');} // see timing notes in header return SPI2->DR; // return received data from SPI data register} // end writeWord()Not sure what exactly could be wrong, I already tried different board with same effect.
Using the debugger (IAR) and checking SPI->DR it never changes to a value even when I am writing to it. is this maybe showing a symptom of malfunction?