How to configure SPI1 in Nucleo L476RG in SPI_DATASIZE_8BIT mode

[David Krcmarik]

Hello,

please can I ask how to configure SPI1 in Nucleo L476RG? I have configured SPI interface using CubeMX and then I have checked the functionality using osciloscope. When I want to send 1 byte (8 bits) CLK signal generated has 16 pulses instead of 8 pulses. My configuration of SPI is:

static void MX_SPI1_Init(void) {

/* SPI1 parameter configuration*/

hspi1.Instance = SPI1;

hspi1.Init.Mode = SPI_MODE_MASTER;

hspi1.Init.Direction = SPI_DIRECTION_2LINES;

hspi1.Init.DataSize = SPI_DATASIZE_8BIT;

hspi1.Init.CLKPolarity = SPI_POLARITY_HIGH;

hspi1.Init.CLKPhase = SPI_PHASE_2EDGE;

hspi1.Init.NSS = SPI_NSS_SOFT;

hspi1.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_16;

hspi1.Init.FirstBit = SPI_FIRSTBIT_MSB;

hspi1.Init.TIMode = SPI_TIMODE_DISABLE;

hspi1.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;

hspi1.Init.CRCPolynomial = 7;

hspi1.Init.CRCLength = SPI_CRC_LENGTH_DATASIZE;

hspi1.Init.NSSPMode = SPI_NSS_PULSE_DISABLE;

if (HAL_SPI_Init(&hspi1) != HAL_OK) {

_Error_Handler(__FILE__, __LINE__);

}

}

I have checked also the registers in HAL_SPI_Init and everything seems fine. Basically when I choose some hspi1.Init.DataSize the number of CLK pulses is always doubled. It seems to me it could be some problem in HAL. Please can you help me how to configure SPI in a such way I would be able to use it for hspi1.Init.DataSize = SPI_DATASIZE_8BIT (it means 8 CLK pulses for each byte)? Attached is a screenshot from osciloscope and program.

David Krcmarik

[David Krcmarik]

I have forget this function definition for code:

int32_t SPI_WriteReadByte(uint8_t data)

{

while (!__HAL_SPI_GET_FLAG(&hspi1, SPI_FLAG_TXE));

hspi1.Instance->DR = data;

while (!__HAL_SPI_GET_FLAG(&hspi1, SPI_FLAG_RXNE));

return (int32_t)hspi1.Instance->DR;

}

[Tesla DeLorean]

Watch the width of the write to DR lest it stuff 16-bits worth of data into the FIFO

*((volatile uint8_t *)&hspi1.Instance->DR) = data;

[David Krcmarik]

Thanks this works.