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STM32L152 Discovery I2C problem with status register

Question asked by doljak.rok on Jul 11, 2014
Hello 

My problem is that i cannot communicate with the temperature sensor via I2C because the code stop working and the problem is in the status register but i dont know how to fix it
can anybody can help me ?

this is the communication code:

#include <stm32l1xx.h>
#include <stm32l1xx_i2c.h>


// this slave address belongs to the STM32F4-Discovery board's
// CS43L22 Audio DAC
// connect PD4 to VDD in order to get the DAC out of reset and test the I2C
// interface
#define SLAVE_ADDRESS 0x40 // the slave address 

void I2C1_init(void){


     GPIO_InitTypeDef GPIO_InitStruct;
     I2C_InitTypeDef I2C_InitStruct;


     // enable APB1 peripheral clock for I2C1
     RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2C1, ENABLE);
     // enable clock for SCL and SDA pins
     RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOB, ENABLE);


     /* setup SCL and SDA pins
      * You can connect the I2C1 functions to two different
      * pins:
      * 1. SCL on PB6 or PB8
      * 2. SDA on PB7 or PB9
      */
     GPIO_InitStruct.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7; // we are going to use PB6 and PB7
     GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;               // set pins to alternate function
     GPIO_InitStruct.GPIO_Speed = GPIO_Speed_2MHz;          // set GPIO speed
     GPIO_InitStruct.GPIO_OType = GPIO_OType_OD;               // set output to open drain --> the line has to be only pulled low, not driven high
     GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_UP;               // enable pull up resistors
     GPIO_Init(GPIOB, &GPIO_InitStruct);                         // init GPIOB


     // Connect I2C1 pins to AF
     GPIO_PinAFConfig(GPIOB, GPIO_PinSource6, GPIO_AF_I2C1);     // SCL
     GPIO_PinAFConfig(GPIOB, GPIO_PinSource7, GPIO_AF_I2C1); // SDA


     // configure I2C1
     I2C_InitStruct.I2C_ClockSpeed = 100000;           // 100kHz
     I2C_InitStruct.I2C_Mode = I2C_Mode_I2C;               // I2C mode
     I2C_InitStruct.I2C_DutyCycle = I2C_DutyCycle_2;     // 50% duty cycle --> standard
     I2C_InitStruct.I2C_OwnAddress1 = 0x00;               // own address, not relevant in master mode
     I2C_InitStruct.I2C_Ack = I2C_Ack_Disable;          // disable acknowledge when reading (can be changed later on)
     I2C_InitStruct.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit; // set address length to 7 bit addresses
     I2C_Init(I2C1, &I2C_InitStruct);                    // init I2C1


     // enable I2C1
     I2C_Cmd(I2C1, ENABLE);
}


/* This function issues a start condition and
 * transmits the slave address + R/W bit
 *
 * Parameters:
 *           I2Cx --> the I2C peripheral e.g. I2C1
 *           address --> the 7 bit slave address
 *           direction --> the transmission direction can be:
 *                               I2C_Direction_Tranmitter for Master transmitter mode
 *                               I2C_Direction_Receiver for Master receiver
 */
void I2C_start(I2C_TypeDef* I2Cx, uint8_t address, uint8_t direction){
     // wait until I2C1 is not busy any more
     while(I2C_GetFlagStatus(I2Cx, I2C_FLAG_BUSY));


     // Send I2C1 START condition
     I2C_GenerateSTART(I2Cx, ENABLE);


     // wait for I2C1 EV5 --> Slave has acknowledged start condition
     while(!I2C_CheckEvent(I2Cx, I2C_EVENT_MASTER_MODE_SELECT));


     // Send slave Address for write
     I2C_Send7bitAddress(I2Cx, address, direction);


     /* wait for I2Cx EV6, check if
      * either Slave has acknowledged Master transmitter or
      * Master receiver mode, depending on the transmission
      * direction
      */
     if(direction == I2C_Direction_Transmitter){
          while(!I2C_CheckEvent(I2Cx, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED));
     }
     else if(direction == I2C_Direction_Receiver){
          while(!I2C_CheckEvent(I2Cx, I2C_EVENT_MASTER_RECEIVER_MODE_SELECTED));
     }
}


/* This function transmits one byte to the slave device
 * Parameters:
 *          I2Cx --> the I2C peripheral e.g. I2C1
 *          data --> the data byte to be transmitted
 */
void I2C_write(I2C_TypeDef* I2Cx, uint8_t data)
{
     // wait for I2C1 EV8 --> last byte is still being transmitted (last byte in SR, buffer empty), next byte can already be written
     while(!I2C_CheckEvent(I2Cx, I2C_EVENT_MASTER_BYTE_TRANSMITTING));
     I2C_SendData(I2Cx, data);
}


/* This function reads one byte from the slave device
 * and acknowledges the byte (requests another byte)
 */
uint8_t I2C_read_ack(I2C_TypeDef* I2Cx){
     // enable acknowledge of received data
     I2C_AcknowledgeConfig(I2Cx, ENABLE);
     // wait until one byte has been received
     while( !I2C_CheckEvent(I2Cx, I2C_EVENT_MASTER_BYTE_RECEIVED) );
     // read data from I2C data register and return data byte
     uint8_t data = I2C_ReceiveData(I2Cx);
     return data;
}


/* This function reads one byte from the slave device
 * and doesn't acknowledge the received data
 * after that a STOP condition is transmitted
 */
uint8_t I2C_read_nack(I2C_TypeDef* I2Cx){
     // disable acknowledge of received data
     // nack also generates stop condition after last byte received
     // see reference manual for more info
     I2C_AcknowledgeConfig(I2Cx, DISABLE);
     I2C_GenerateSTOP(I2Cx, ENABLE);
     // wait until one byte has been received
     while( !I2C_CheckEvent(I2Cx, I2C_EVENT_MASTER_BYTE_RECEIVED) );
     // read data from I2C data register and return data byte
     uint8_t data = I2C_ReceiveData(I2Cx);
     return data;
}


/* This function issues a stop condition and therefore
 * releases the bus
 */
void I2C_stop(I2C_TypeDef* I2Cx){


     // Send I2C1 STOP Condition after last byte has been transmitted
     I2C_GenerateSTOP(I2Cx, ENABLE);
     // wait for I2C1 EV8_2 --> byte has been transmitted
     while(!I2C_CheckEvent(I2Cx, I2C_EVENT_MASTER_BYTE_TRANSMITTED));
}


int main(void){


     I2C1_init(); // initialize I2C peripheral


     uint8_t received_data;


     I2C_start(I2C1, SLAVE_ADDRESS<<1, I2C_Direction_Transmitter); // start a transmission in Master transmitter mode
     I2C_write(I2C1, 0x01); // write one byte to the slave
     I2C_stop(I2C1); // stop the transmission


     I2C_start(I2C1, SLAVE_ADDRESS<<1, I2C_Direction_Receiver); // start a transmission in Master receiver mode
     received_data = I2C_read_nack(I2C1); // read one byte and don't request another byte, stop transmission


     while(1);
     return 0;

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