Question
I2C TXDR doesnt send the data on SDA. STM32F3 Discovery.
Posted on July 03, 2016 at 14:04
Sample program to get accelerometer data.
#include ''stm32f3xx.h'' // Device header
void
initSystem()
{
// LSM303DLHC wiring: SCL to PB6, SDA to PB7.
// Enable port B timing and set pins to alternate function mode. No pull-up/pull-down.
RCC->AHBENR |= RCC_AHBENR_GPIOBEN;
GPIOB->MODER |= GPIO_MODER_MODER6_1|GPIO_MODER_MODER7_1;
GPIOB->OTYPER |= GPIO_OTYPER_OT_6|GPIO_OTYPER_OT_7;
GPIOB->PUPDR &= ~(GPIO_PUPDR_PUPDR6 | GPIO_PUPDR_PUPDR7 );
GPIOB->OSPEEDR |= GPIO_OSPEEDER_OSPEEDR6 |GPIO_OSPEEDER_OSPEEDR7;
// Select AF4 (0100=0x4) to toggle I2C_SCL function on pin PB6 and I2C_SDA on pin PB7.
GPIOB->AFR[0] |= (0x4 << GPIO_AFRL_AFRL6_Pos);
GPIOB->AFR[0] |= (0x4 << GPIO_AFRL_AFRL7_Pos);
// Enable I2C peripheral clock.
RCC->APB1ENR |= RCC_APB1ENR_I2C1EN;
// Set up TIMINGR (CubeMX).
I2C1->TIMINGR = 0x00501E26;
// Peripheral Enable.
I2C1->CR1 |= I2C_CR1_PE;
}
// Variable to store the data.
uint32_t buffer[5];
// Counter.
uint32_t i = 5;
int
main()
{
initSystem();
// Set up CR2 register for data writing.
I2C1->CR2 |= (I2C_CR2_NBYTES & 1);
// 1 byte to transfer (NBYTES).
I2C1->CR2 &= ~I2C_CR2_RD_WRN;
// Write. Set 0 in RD_WRN bit for transfer direction in master mode.
I2C1->CR2 |= 0x19 << 1;
// Accelerometer address (without r/w bit).
I2C1->CR2 |= I2C_CR2_START;
// Set START bit. Master sends start condition, slave address and R/W bit.
while
((I2C1->ISR & I2C_ISR_TC) == 0);
// Wait for transfer complete.
I2C1->TXDR = 0x28;
// Put data (inernal registry address) into TXDR.
while
((I2C1->ISR & I2C_ISR_TXIS) == 0);
// Wait for TXDR is empty and ready for the new data.
// Set up CR2 register for data reading and set START bit.
I2C1->CR2 = I2C_CR2_AUTOEND | (I2C_CR2_NBYTES & 5) | I2C_CR2_RD_WRN | 0x19 << 1;
I2C1->CR2 |= I2C_CR2_START;
// Read the data.
while
(i-- > 0)
{
while
((I2C1->ISR & I2C_ISR_RXNE) == 0);
// Wait for recieve data register is ready.
buffer [i] = I2C1->RXDR;
// Copy the data from recieve data register.
}
while
(1)
{
}
}