SPI 9bit FOR STM32F0

Question

Posted on March 14, 2014 at 07:25 Hello everyone. I'm working with STM32F0.I'm want to make 9 bits of data to be transferred via SPI. I've done the initial configuration for the SPI but it seems like the main program that I made wrong because when I check on the oscilloscope, MISO or MOSI do not have data pulse. please help me find where the mistake. thanks for your help #include ''stm32f0xx.h'' #include ''stm32f0xx_gpio.h'' #include ''stm32f0xx_rcc.h'' #include ''stm32f0xx_tim.h'' #include ''stm32f0xx_spi.h'' void mx_pinout_config(void) { GPIO_InitTypeDef GPIO_InitStruct; RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE); RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOB, ENABLE); GPIO_InitStruct.GPIO_Pin = GPIO_Pin_4; GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF; GPIO_InitStruct.GPIO_OType = GPIO_OType_PP; GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL; GPIO_InitStruct.GPIO_Speed = GPIO_Speed_2MHz; GPIO_Init(GPIOA, &GPIO_InitStruct); GPIO_InitStruct.GPIO_Pin = GPIO_Pin_5; GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF; GPIO_InitStruct.GPIO_OType = GPIO_OType_PP; GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL; GPIO_InitStruct.GPIO_Speed = GPIO_Speed_2MHz; GPIO_Init(GPIOA, &GPIO_InitStruct); GPIO_InitStruct.GPIO_Pin = GPIO_Pin_6; GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF; GPIO_InitStruct.GPIO_OType = GPIO_OType_PP; GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL; GPIO_InitStruct.GPIO_Speed = GPIO_Speed_2MHz; GPIO_Init(GPIOA, &GPIO_InitStruct); GPIO_InitStruct.GPIO_Pin = GPIO_Pin_7; GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF; GPIO_InitStruct.GPIO_OType = GPIO_OType_PP; GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL; GPIO_InitStruct.GPIO_Speed = GPIO_Speed_2MHz; GPIO_Init(GPIOA, &GPIO_InitStruct); GPIO_InitStruct.GPIO_Pin = GPIO_Pin_7; GPIO_InitStruct.GPIO_Mode = GPIO_Mode_OUT; GPIO_InitStruct.GPIO_OType = GPIO_OType_PP; GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL; GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz; GPIO_Init(GPIOB, &GPIO_InitStruct); GPIOB->BSRR |= (0x01<< 6 ); } void SPI_config(void) { SPI_InitTypeDef SPI_InitStruct; SPI_InitStruct.SPI_Direction = SPI_Direction_2Lines_FullDuplex ; SPI_InitStruct.SPI_Mode = SPI_Mode_Master ; SPI_InitStruct.SPI_DataSize = SPI_DataSize_9b ; SPI_InitStruct.SPI_CPOL = SPI_CPOL_Low ; SPI_InitStruct.SPI_CPHA = SPI_CPHA_1Edge ; SPI_InitStruct.SPI_NSS = SPI_NSS_Soft ; SPI_InitStruct.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_128 ; // 42000kHz/ 128 = 328kHz < 400kHz SPI_InitStruct.SPI_FirstBit = SPI_FirstBit_MSB ; SPI_InitStruct.SPI_CRCPolynomial = 7 ; SPI_Init(SPI1, &SPI_InitStruct); SPI_Cmd(SPI1, ENABLE); // enable SPI1 } uint8_t SPI1_send(uint8_t data){ SPI1->DR = data; // write data to be transmitted to the SPI data register while( !(SPI1->SR & SPI_I2S_FLAG_TXE) ); // wait until transmit complete while( !(SPI1->SR & SPI_I2S_FLAG_RXNE) ); // wait until receive complete while( SPI1->SR & SPI_I2S_FLAG_BSY ); // wait until SPI is not busy anymore return SPI1->DR; // return received data from SPI data register } int main(void) { uint8_t received_val = 0; mx_pinout_config(); SPI_config(); while(1) { SPI1_send(0xAA); // transmit data } }

hkamba · Answer

Posted on March 14, 2014 at 10:26  Hi Hakim,   I recently worked on STM32F030C8 and wrote an SPI driver for it. I observed that no matter how you try to set the SPI_CR2_DS_x bits of SPIx_CR2 register, it always revert back to 8-bit data. I do not know if it is an issue known to STM...   Below is my initialisation:    void SPI2_init( void ){ RCC->APB1ENR |= RCC_APB1ENR_SPI2EN; // Enable APB1 peripheral clock for SPI2RCC->AHBENR |= RCC_AHBENR_GPIOBEN; // Enable the peripheral clock for SPI2 pins// Set PB12, PB13, PB14 and PB15 as Alternate function, Open-drain, 2MHz, pull-downGPIOB->MODER &= ~( GPIO_MODER_MODER12 | GPIO_MODER_MODER13 | GPIO_MODER_MODER14 | GPIO_MODER_MODER15 );GPIOB->MODER |= ( GPIO_MODER_MODER12_1 | GPIO_MODER_MODER13_1 | GPIO_MODER_MODER14_1 | GPIO_MODER_MODER15_1 ); // Alternate functionGPIOB->OTYPER &= ~( GPIO_OTYPER_OT_12 | GPIO_OTYPER_OT_13 | GPIO_OTYPER_OT_14 | GPIO_OTYPER_OT_15 ); // Output push-pullGPIOB->OSPEEDR &= ~( GPIO_OSPEEDER_OSPEEDR12 | GPIO_OSPEEDER_OSPEEDR13 | GPIO_OSPEEDER_OSPEEDR14 | GPIO_OSPEEDER_OSPEEDR15 ); // Low speedGPIOB->PUPDR &= ~( GPIO_PUPDR_PUPDR12 | GPIO_PUPDR_PUPDR13 | GPIO_PUPDR_PUPDR14 | GPIO_PUPDR_PUPDR15 );GPIOB->PUPDR |= ( GPIO_PUPDR_PUPDR12_1 | GPIO_PUPDR_PUPDR13_1 | GPIO_PUPDR_PUPDR14_1 | GPIO_PUPDR_PUPDR15_1 ); // Pull-down// Select SPI Alternate Function for PB12 (SPI2_NSS), PB13 (SPI2_SCK), PB14 (SPI2_MISO), and PB15 (SPI2_MOSI) pinsGPIOB->AFR[1] &= ~( GPIO_AFRH_AFRH4 | GPIO_AFRH_AFRH5 | GPIO_AFRH_AFRH6 | GPIO_AFRH_AFRH7 ); SPI2->CR1 &= 0x0000;SPI2->CR2 &= 0x0000;if ( SysInfo.CommsMode == SPI_MASTER ){// No CRC, Full duplex, MSB first, PCLK/128 Hz, Master mode, Mode 0 (Note: PCLK = 8 MHz)SPI2->CR1 |= ( (SPI_CR1_BR_2 | SPI_CR1_BR_1) | SPI_CR1_MSTR ); }if ( SysInfo.CommsMode == SPI_SLAVE ){// No CRC, Full duplex, MSB first, PCLK/128 Hz, Slave mode, Mode 0 (Note: PCLK = 8 MHz)SPI2->CR1 |= ( (SPI_CR1_BR_2 | SPI_CR1_BR_1) );} // 8-bit data transfer, Motorola mode, NSSP, SSOESPI2->CR2 |= SPI_CR2_FRXTH | (SPI_CR2_DS_0 | SPI_CR2_DS_1 | SPI_CR2_DS_2) | SPI_CR2_RXNEIE | SPI_CR2_NSSP | SPI_CR2_SSOE; SPI2->CR1 |= SPI_CR1_SPE; // SPI enabledtxBuf = (uint8_t*)&SPI2->DR; // Necessary to send only 8-bit and not two chucnks of 8 bits by accessing the SPI2_DR register directly!!NVIC_SetPriority(SPI2_IRQn, NVIC_PRIO_SPI2); // Configure SPI2 IRQNVIC_EnableIRQ(SPI2_IRQn); // Enable SPI2 IRQif ( SysInfo.CommsMode == SPI_MASTER ){TIMER1_set( TIMER_SPIRXPOLL, SPI2_rx_poll, SPIRXPOLL_TIMER, TIMER_REPEATING ); // Register SPI2 poll timer callback}if ( SysInfo.CommsMode == SPI_SLAVE ){ spi2_init_irq();}}

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