STM32F0, I2C sends wrong data.

[hotek]

Posted on December 18, 2013 at 21:57

Hello.

I have a problem to cinfigure I2C. This is my code: &sharpdefine    PRESC    0x0B &sharpdefine    SCLL    0x13 &sharpdefine    SCLH    0x0F &sharpdefine    SDADEL    0x02 &sharpdefine    SCLDEL    0x04   void I2C_PCF_init() {     RCC->AHBENR|=RCC_AHBENR_GPIOBEN;     GPIOB->MODER|= GPIO_MODER_MODER6_1|GPIO_MODER_MODER7_1;      GPIOB->OSPEEDR|=GPIO_OSPEEDER_OSPEEDR6|GPIO_OSPEEDER_OSPEEDR7;//predkosc 50MHZ     GPIOB->AFR[0]|=0x11000000;    //AF1       RCC->APB1ENR|=RCC_APB1ENR_I2C1EN ;        //enable clock for I2C1       I2C1->CR1|=I2C_CR1_PE;                    //set PE     I2C1->CR1&=~I2C_CR1_PE;                    //reset PE     while(I2C1->CR1&I2C_CR1_PE);            //while PE ==1       I2C1->TIMINGR|=(PRESC << 28)|(SCLL<<0)|(SCLH<<8)|(SCLDEL<<20)|(SDADEL<<16); //configure for 48Mhz clock       I2C1->CR1|=I2C_CR1_PE;                    //set PE } void I2C_PCF_send(int adress, int lenght) {     I2C1->CR2|=(adress<<0)|(lenght<<16)|I2C_CR2_ADD10;    //addres SLAVE 10bits     I2C1->CR2 &=~ I2C_CR2_RD_WRN;                        //write     I2C1->CR2 |= I2C_CR2_START;       I2C1->TXDR=0xff;     while(I2C1->ISR&I2C_ISR_TXIS);            //wait for TXDR will be empty and data was send.       I2C1->CR2|=I2C_CR2_STOP; } No matter what i write after this part: I2C1->CR2 |= I2C_CR2_START; I2C sending data like this: Can somebody tell me what im doing wrong, and why data from buffer TXDR are not sent? #problem #stm32f0-i2c

[chen]

Posted on December 19, 2013 at 11:30

Hi

I think     I2C1->CR2|=(adress<<0)|(lenght<<16)|I2C_CR2_ADD10;    //addres SLAVE 10bits     I2C1->CR2 &=~ I2C_CR2_RD_WRN;                        //write     I2C1->CR2 |= I2C_CR2_START; Tells the I2C controller to send the start bit and the device address. BUT then you immediately do    I2C1->TXDR=0xff; Then try to wait for the data to be transmitted.       while(I2C1->ISR&I2C_ISR_TXIS); You need to wait for the start bit and the device address to complete before trying to send the data. You need to add another ''while(I2C1->ISR&I2C_ISR_TXIS);'' or something before the ''I2C1->TXDR=0xff;'' Some points to consider : 1. READ THE MANUAL/DATA SHEET! Understand the I2C controller. 2. The while loops do not have any timeout/escape conditions - your program could get stuck at the while loops.

[hotek]

Posted on December 19, 2013 at 19:28

Thank you for response.

The problem was here:  I2C1->CR2|=(adress<<0)|(lenght<<16)|I2C_CR2_ADD10;    //address SLAVE 10bits I was try to send 8 bits address, but that was send only 2 MSBs on 10bits mode, and slave dont send ACK, so master try to send again that 2 bits. This is working ''write'' code: void I2C_PCF_send(int address, int length) {     while ((I2C1->ISR & I2C_ISR_TXE)==0);    //while TXE ==0, buffer is full     I2C1->CR2|=(address<<0)|(length<<16)| I2C_CR2_AUTOEND ;    //address SLAVE 7bits     I2C1->CR2 &=~ I2C_CR2_RD_WRN;                        //write     I2C1->CR2 |= I2C_CR2_START;     while ((I2C1->ISR & I2C_ISR_TXE)==0);    //while TXE ==0, buffer is full     I2C1->TXDR=0xff; }