Posted on August 09, 2017 at 23:28
Hi,
There seems to be an issue with the SPI peripheral in the STM32F10x family of devices.
I have the same issue with multiple devices (STM32F103ZGT8, STM32F107VCT6)
Here is the issue:
When I try to read in master mode, I must send data for the peripheral to send out a clock so I can read the data.
When I am reading data, I am reading back what I sent.
I have used the SPI in interrupt and with DMA and have the same issue.
When I try to write/read, I read the first byte properly, but then I read back what I placed in the DR register
Using a logic analyzer, I was able to see that my master and slave are transmitting the bytes properly.
From this stream, I would expect to read 0xFF 8 times.
However, my RX buffer will contain: 0xFF 0x12 0x34 0x56 0x78 0x9A 0xBC 0xDE
When using breakpoints in interrupt mode, here is the sequence of events that I have seen.
- When we start the transfer, we place the first byte in the DR register
- We then enable the TXE interrupt.
- This generates aninterrupt.
- In the ISR, we place the next byte in the DR register while the previous one is transmitted.
- Some time later, we receive a byte which triggers the RXNE interrupt
- In the ISR, we read back the byte from the DR register.
- An interrupt is generated when the last byte is transfered
- We repeat these from step 4 until all bytes have been transmiited/read
The odd thing is that we get a TXE interrupt (step 2) even though we are still transferring the first byte. This means that we have not read single byte but we have already given the SPI peripheral 2 bytes.
Here is thehypothesis I have arrived to:
It seems that the DR register overwrites the data in the RX buffer if I write to it too soon.This makes the use of the DMA for reading data useless.
I was able to resolve the issue by followingthe steps below (this only works in interrupt mode):
- Place first byte in the DR register
- Wait for RXNE interrupt.
- Read data in DR.
- Place next byte in DR register.
- Repeat from step 2
I originally used the HAL that comes with STMcubemx but had to write my own code to properly manage the SPI transfers.
Is this a known issue with the STM32F10x devices? Or am I missing something?
Below is my init code with DMA:
// To transfer data with the SPI in DMA mode, I use thiss line of code:
HAL_StatusTypeDef status = HAL_SPI_TransmitReceive_DMA(&hSpi, txData, rxData, size);
/**
* @brief This function initializes the SPI peripheral
* @param None
* @retval None
*/
void SPI_Init(void)
{
spiEventHandle = xEventGroupCreateStatic(&spiEvent);
hSpi.Instance = SPI1;
hSpi.Init.Mode = SPI_MODE_MASTER;
hSpi.Init.Direction = SPI_DIRECTION_2LINES;
hSpi.Init.DataSize = SPI_DATASIZE_8BIT;
hSpi.Init.CLKPolarity = SPI_POLARITY_LOW;
hSpi.Init.CLKPhase = SPI_PHASE_1EDGE;
hSpi.Init.NSS = SPI_NSS_SOFT;
hSpi.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_256;
hSpi.Init.FirstBit = SPI_FIRSTBIT_MSB;
hSpi.Init.TIMode = SPI_TIMODE_DISABLE;
hSpi.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;
hSpi.Init.CRCPolynomial = 10;
if (HAL_SPI_Init(&hSpi) != HAL_OK)
{
_Error_Handler(__FILE__, __LINE__);
}
}
/**
* @brief This function initializes the low level peripherals used by the SPI
* @param SPI_HandleTypeDef * - pointer to the SPI handle
* @retval None
*/
void HAL_SPI_MspInit(SPI_HandleTypeDef *spiHandle)
{
// Enable SPI1 clock
__HAL_RCC_SPI1_CLK_ENABLE();
// SPI1 GPIO Configuration
GPIO_InitPin(SPI_CS);
GPIO_InitPin(SPI_SCK);
GPIO_InitPin(SPI_MOSI);
GPIO_InitPin(SPI_MISO);
// SPI1 DMA Init
// SPI1_RX Init
hDmaSpiRx.Instance = DMA1_Channel2;
hDmaSpiRx.Init.Direction = DMA_PERIPH_TO_MEMORY;
hDmaSpiRx.Init.PeriphInc = DMA_PINC_DISABLE;
hDmaSpiRx.Init.MemInc = DMA_MINC_ENABLE;
hDmaSpiRx.Init.PeriphDataAlignment = DMA_PDATAALIGN_BYTE;
hDmaSpiRx.Init.MemDataAlignment = DMA_MDATAALIGN_BYTE;
hDmaSpiRx.Init.Mode = DMA_NORMAL;
hDmaSpiRx.Init.Priority = DMA_PRIORITY_LOW;
if (HAL_DMA_Init(&hDmaSpiRx) != HAL_OK)
{
_Error_Handler(__FILE__, __LINE__);
}
__HAL_LINKDMA(spiHandle, hdmarx, hDmaSpiRx);
// SPI1_TX Init
hDmaSpiTx.Instance = DMA1_Channel3;
hDmaSpiTx.Init.Direction = DMA_MEMORY_TO_PERIPH;
hDmaSpiTx.Init.PeriphInc = DMA_PINC_DISABLE;
hDmaSpiTx.Init.MemInc = DMA_MINC_ENABLE;
hDmaSpiTx.Init.PeriphDataAlignment = DMA_PDATAALIGN_BYTE;
hDmaSpiTx.Init.MemDataAlignment = DMA_MDATAALIGN_BYTE;
hDmaSpiTx.Init.Mode = DMA_NORMAL;
hDmaSpiTx.Init.Priority = DMA_PRIORITY_LOW;
if (HAL_DMA_Init(&hDmaSpiTx) != HAL_OK)
{
_Error_Handler(__FILE__, __LINE__);
}
__HAL_LINKDMA(spiHandle, hdmatx, hDmaSpiTx);
}
/**
* @brief This function initializes the DMA peripheral
* @param None
* @retval None
*/
void DMA_Init(void)
{
// DMA controller clock enable
__HAL_RCC_DMA1_CLK_ENABLE();
}
/**
* @brief This function enables the interrupts used by the DMA
* @param None
* @retval None
*/
void DMA_EnableIrq(void)
{
// DMA interrupt init
// DMA1_Channel2_IRQn interrupt configuration
HAL_NVIC_SetPriority(DMA1_Channel2_IRQn, 7, 0);
HAL_NVIC_EnableIRQ(DMA1_Channel2_IRQn);
// DMA1_Channel3_IRQn interrupt configuration
HAL_NVIC_SetPriority(DMA1_Channel3_IRQn, 7, 0);
HAL_NVIC_EnableIRQ(DMA1_Channel3_IRQn);
}
/**
* @brief This function handles DMA1 channel2 global interrupt.
*/
void DMA1_Channel2_IRQHandler(void)
{
HAL_DMA_IRQHandler(&hDmaSpiRx);
}
/**
* @brief This function handles DMA1 channel3 global interrupt.
*/
void DMA1_Channel3_IRQHandler(void)
{
HAL_DMA_IRQHandler(&hDmaSpiTx);
}
/**
* @brief This function is a callback used to notify when a transfer is completed
* @note This function is called by the HAL
* @param SPI_HandleTypeDef * - pointer to the SPI handle
* @retval None
*/
void HAL_SPI_TxRxCpltCallback(SPI_HandleTypeDef *hspi)
{
BaseType_t xHigherPriorityTaskWoken;
BaseType_t result = xEventGroupSetBitsFromISR(spiEventHandle, SPI_EVENT_SUCCESS, &xHigherPriorityTaskWoken);
if (result == pdPASS)
{
/* If xHigherPriorityTaskWoken is now set to pdTRUE then a context
switch should be requested. */
portYIELD_FROM_ISR(xHigherPriorityTaskWoken);
}
}
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Michel
