Hello everbody,
Im using a STM32F303 and want to communicate with a MAX31855.
Im using the STM in full duplex master mode, under 1MBit/s data rate and standard settings.
CS ist working fine, SCK is working fine (want to read 4 times 8 bit, 32 pulses), but the connection between MISO at the STM and Data Out (DO) from MAX stays low with 32 little peaks in phase with the clock frequency (see picture: verbundene Leitung).
If I disconnect the STM from the MAX31855, I can see the right data on the Oscilloscope (see picture: offene Leitung). No shorts between the pins on the STM, no shorts to vcc or ground.
I have no idea what is going wrong. All SPI Settings are generated with the CUBE IDE.
CODE:
Generated spi.c
void MX_SPI2_Init(void)
{
hspi2.Instance = SPI2;
hspi2.Init.Mode = SPI_MODE_MASTER;
hspi2.Init.Direction = SPI_DIRECTION_2LINES;
hspi2.Init.DataSize = SPI_DATASIZE_8BIT;
hspi2.Init.CLKPolarity = SPI_POLARITY_LOW;
hspi2.Init.CLKPhase = SPI_PHASE_1EDGE;
hspi2.Init.NSS = SPI_NSS_SOFT;
hspi2.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_128;
hspi2.Init.FirstBit = SPI_FIRSTBIT_MSB;
hspi2.Init.TIMode = SPI_TIMODE_DISABLE;
hspi2.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;
hspi2.Init.CRCPolynomial = 7;
hspi2.Init.CRCLength = SPI_CRC_LENGTH_DATASIZE;
hspi2.Init.NSSPMode = SPI_NSS_PULSE_ENABLE;
if (HAL_SPI_Init(&hspi2) != HAL_OK)
{
Error_Handler();
}
}
void HAL_SPI_MspInit(SPI_HandleTypeDef* spiHandle)
{
GPIO_InitTypeDef GPIO_InitStruct = {0};
if(spiHandle->Instance==SPI2)
{
/* USER CODE BEGIN SPI2_MspInit 0 */
/* USER CODE END SPI2_MspInit 0 */
/* SPI2 clock enable */
__HAL_RCC_SPI2_CLK_ENABLE();
__HAL_RCC_GPIOB_CLK_ENABLE();
/**SPI2 GPIO Configuration
PB13 ------> SPI2_SCK
PB14 ------> SPI2_MISO
PB15 ------> SPI2_MOSI
*/
GPIO_InitStruct.Pin = GPIO_PIN_13|GPIO_PIN_14|GPIO_PIN_15;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF5_SPI2;
HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
/* SPI2 interrupt Init */
HAL_NVIC_SetPriority(SPI2_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(SPI2_IRQn);
/* USER CODE BEGIN SPI2_MspInit 1 */
/* USER CODE END SPI2_MspInit 1 */
}
}
main.c
HAL_Delay(50);
uint8_t buffer_max[4];
HAL_GPIO_WritePin(SPI2_CS_GPIO_Port,SPI2_CS_Pin, GPIO_PIN_RESET);
HAL_SPI_Receive(&hspi2,buffer_max,4,100);
HAL_GPIO_WritePin(SPI2_CS_GPIO_Port,SPI2_CS_Pin, GPIO_PIN_SET);
HAL_Delay(50);
