Posted on February 28, 2015 at 10:47Hi. I'm trying to set the spi at max speed (in theory 30mbit/s spi in stm32F2), but I just get 15mbits on SPI output.
This is my spi initialization (for SPI3).
I'm using DMA to transfer a buffer, but in theory that is independent of SPI speed.
Where is my problem?
//SPI3 initialization
static void SPI_Config(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
SPI_InitTypeDef SPI_InitStructure;
/* Peripheral Clock Enable -------------------------------------------------*/
/* Enable the SPI clock */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_SPI3, ENABLE);
/* Enable GPIO clocks */
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE);
/* SPI GPIO Configuration --------------------------------------------------*/
GPIO_PinAFConfig(GPIOC, GPIO_PinSource12, GPIO_AF_SPI3);
GPIO_PinAFConfig(GPIOC, GPIO_PinSource10, GPIO_AF_SPI3);
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_DOWN;
/*!< SPI SCK pin configuration */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12;
GPIO_Init(GPIOC, &GPIO_InitStructure);
/*!< SPI MOSI pin configuration */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
GPIO_Init(GPIOC, &GPIO_InitStructure);
/* SPI configuration -------------------------------------------------------*/
SPI_I2S_DeInit(SPI3);
SPI_InitStructure.SPI_Direction = SPI_Direction_1Line_Tx;
SPI_InitStructure.SPI_Mode = SPI_Mode_Master;
SPI_InitStructure.SPI_DataSize = SPI_DataSize_8b;
SPI_InitStructure.SPI_CPOL = SPI_CPOL_Low;
SPI_InitStructure.SPI_CPHA = SPI_CPHA_1Edge;
SPI_InitStructure.SPI_NSS = SPI_NSS_Soft;
SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_2;
SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;
SPI_InitStructure.SPI_CRCPolynomial = 7;
SPI_Init(SPI3, &SPI_InitStructure);
SPI_Cmd(SPI3, ENABLE);
}
#spi3 #dma #spi
