SPI2 Problem STM32F303CC

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);