Posted on October 10, 2016 at 11:05
Hello, I have a question about SPI. I start spi in receive mode only with dma. I receive correct data but if I want to receive only one sample, I see 32 clocks instead of 16 clock.
void spi_init()
{
spi_handler.Instance = SPI2;
spi_handler.Init.Mode = SPI_MODE_MASTER;
spi_handler.Init.Direction = SPI_DIRECTION_2LINES_RXONLY; // Receive mode only
spi_handler.Init.DataSize = SPI_DATASIZE_16BIT;
spi_handler.Init.CLKPolarity = SPI_POLARITY_LOW;
spi_handler.Init.CLKPhase = SPI_PHASE_1EDGE;
spi_handler.Init.NSS = SPI_NSS_HARD_OUTPUT;
spi_handler.Init.NSSPMode = SPI_NSS_PULSE_ENABLE;
spi_handler.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_64;
spi_handler.Init.FirstBit = SPI_FIRSTBIT_MSB;
spi_handler.Init.TIMode = SPI_TIMODE_DISABLE;
spi_handler.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;
HAL_SPI_Init(&spi_handler);
}
void HAL_SPI_MspInit(SPI_HandleTypeDef *hspi)
{
GPIO_InitTypeDef gpio_instruct;
if (hspi->Instance == SPI2)
{
//Enable RX clock for SPI
__HAL_RCC_GPIOI_CLK_ENABLE(); // Enable SCK clk
__HAL_RCC_GPIOB_CLK_ENABLE(); // Enable MISO pin
// Enable SPI2 clock
__HAL_RCC_SPI2_CLK_ENABLE();
// Enable DMA clock
__HAL_RCC_DMA1_CLK_ENABLE();
// SPI CLK pin init
gpio_instruct.Pin = GPIO_PIN_1;
gpio_instruct.Mode = GPIO_MODE_AF_PP;
gpio_instruct.Pull = GPIO_PULLDOWN;
gpio_instruct.Speed = GPIO_SPEED_HIGH;
gpio_instruct.Alternate = GPIO_AF5_SPI2;
HAL_GPIO_Init(GPIOI, &gpio_instruct);
// SPI CS pin init
gpio_instruct.Pin = GPIO_PIN_0;
gpio_instruct.Mode = GPIO_MODE_AF_PP;
gpio_instruct.Pull = GPIO_PULLUP;
gpio_instruct.Speed = GPIO_SPEED_HIGH;
gpio_instruct.Alternate = GPIO_AF5_SPI2;
HAL_GPIO_Init(GPIOI, &gpio_instruct);
// SPI MISO gpio pin init
gpio_instruct.Pin = GPIO_PIN_14;
gpio_instruct.Mode = GPIO_MODE_AF_PP;
gpio_instruct.Pull = GPIO_PULLUP;
gpio_instruct.Alternate = GPIO_AF5_SPI2;
HAL_GPIO_Init(GPIOB, &gpio_instruct);
// Config DMA for receive process
dma_handler_rx.Instance = DMA1_Stream3;
dma_handler_rx.Init.Channel = DMA_CHANNEL_0;
dma_handler_rx.Init.FIFOMode = DMA_FIFOMODE_ENABLE;
dma_handler_rx.Init.FIFOThreshold = DMA_FIFO_THRESHOLD_HALFFULL;
dma_handler_rx.Init.MemBurst = DMA_MBURST_SINGLE;
dma_handler_rx.Init.PeriphBurst = DMA_PBURST_SINGLE;
dma_handler_rx.Init.Direction = DMA_PERIPH_TO_MEMORY;
dma_handler_rx.Init.PeriphInc = DMA_PINC_DISABLE;
dma_handler_rx.Init.MemInc = DMA_MINC_ENABLE;
dma_handler_rx.Init.PeriphDataAlignment = DMA_PDATAALIGN_HALFWORD;
dma_handler_rx.Init.MemDataAlignment = DMA_MDATAALIGN_HALFWORD;
dma_handler_rx.Init.Mode = DMA_NORMAL;
dma_handler_rx.Init.Priority = DMA_PRIORITY_HIGH;
HAL_DMA_Init(&dma_handler_rx);
// Associate the initialized DMA handle to the the SPI handle
__HAL_LINKDMA(hspi, hdmarx, dma_handler_rx);
// Set DMA1 stream 3 priority.
// When 2 interrupts have same preemption priority, then he one who has higher sub priority will be execute first.
// If both interrupts both have same preemption priority and sub priority, the one comes first will be execute first
HAL_NVIC_SetPriority(DMA1_Stream3_IRQn, 1, 1);
HAL_NVIC_EnableIRQ(DMA1_Stream3_IRQn);
// Set SPI2 receive priority.
// When 2 interrupts have same preemption priority, then he one who has higher sub priority will be execute first.
// If both interrupts both have same preemption priority and sub priority, the one comes first will be execute first
HAL_NVIC_SetPriority(SPI2_IRQn, 1, 0);
HAL_NVIC_EnableIRQ(SPI2_IRQn);
}
}
