8 years, 3 months ago.

I2C Stm32f4 , can not read the data

hello everybody, I'm having a problem with reading data from a maximGauge via I2C stm32f4. I used the oscilloscope to check the variations of SDA and SCL. Here the results. As u can see, I have the start signal, the sending address and also an ACK from the gauge. If i understood well, the connections is right while we are having the ACK. Now the data i need to receive is not really sent..

Here the code :

1. include "stm32f4xx.h"
2. include "stm32f4xx_gpio.h"
3. include "stm32f4xx_rcc.h"
4. include "stm32f4xx_i2c.h"

1. define SLAVE_ADDRESS 0x6C the slave address

1. define TIME_OUT 0xA time out constant
2. define I2Cxx I2C1

void I2C1_init(void) {

GPIO_InitTypeDef GPIO_InitStruct; GPIO_InitTypeDef GPIO_InitStruct2; I2C_InitTypeDef I2C_InitStruct;

enable APB1 peripheral clock for I2C1 RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2C1, ENABLE); enable clock for SCL and SDA pins RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE); enable clock for leds RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);

LED configuration GPIOA GPIO_InitStruct2.GPIO_Pin = GPIO_Pin_1; GPIO_InitStruct2.GPIO_Mode = GPIO_Mode_OUT; set pins to OUT mode GPIO_InitStruct2.GPIO_Speed = GPIO_Speed_50MHz; set GPIO speed GPIO_InitStruct2.GPIO_OType = GPIO_OType_PP; pushpull mode GPIO_InitStruct2.GPIO_PuPd = GPIO_PuPd_UP; enable pull up resistors GPIO_Init(GPIOD, &GPIO_InitStruct2); init GPIOB

SCL and SDA configuration GPIOB GPIO_InitStruct.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7; PB6 for SCL and PB7 for SDA GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF; set pins to alternate function GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz; 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 = 200000; 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 (à changer par la suite) I2C_InitStruct.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit; set address length to 7 bit addresses I2C_Init(I2C1, &I2C_InitStruct); init I2C1 GPIO_ResetBits(GPIOD, GPIO_Pin_1); GPIO_SetBits(GPIOD, GPIO_Pin_1);

enable I2C1 I2C_Cmd(I2C1, ENABLE); }

Then the function Read:

void I2C_Read(uint8_t address, uint8_t command, uint8_t *data[2] ) {

uint32_t time_out; time out variable ErrorStatus status = SUCCESS; the status of progress static volatile ErrorStatus end = SUCCESS;

0# Wait until I2C1 is not busy any more Check flag BUSY = 0 time_out = TIME_OUT; while (time_out != 0) { if (I2C_GetFlagStatus(I2Cxx, I2C_FLAG_BUSY) == 1) { time_out--; if (time_out == 0) { status = ERROR; } } else time_out = 0; }

if (status != ERROR) { I2C_GenerateSTART(I2Cxx, ENABLE);

2# Wait for I2C1 EV5(BUSY,MSL,SB)> Slave has acknowledged start condition START correct // After sending the START condition (I2C_GenerateSTART() function) the master has to wait for this event. It means that the Start condition has been correctly // released on the I2C bus (the bus is free, no other devices is communicating). time_out = TIME_OUT; while (time_out != 0) { if (I2C_CheckEvent(I2Cxx, I2C_EVENT_MASTER_MODE_SELECT) == 0) { time_out--; if (time_out == 0) { status = ERROR; } } else time_out = 0; } }

if (status != ERROR) { uint32_t ev; uint32_t tab[TIME_OUT]; int i=0;

3# Send slave Address for write I2C_Send7bitAddress(I2Cxx, address, I2C_Direction_Transmitter); I2C_SendData(I2Cxx, (address << 1) | 0); check if slave acknowledged his address within timeout

time_out = TIME_OUT; while (time_out != 0) { I2C_CheckEvent(I2Cxx,I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED) == 0) ev=I2C_GetLastEvent(I2Cxx); tab[i++]=ev; if (ev!=I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED) {

time_out; if (time_out == 0) { status = ERROR; } } else time_out = 0; }

ev=0; }

if (status != ERROR) {

I2C_SendData(I2Cxx, command); time_out = TIME_OUT; while (time_out != 0) { 6# Check BTF (Byte Transfer Finished) if (I2C_GetFlagStatus(I2Cxx, I2C_FLAG_BTF) == RESET) { time_out; if (time_out == 0) { status = ERROR; } } else time_out = 0;

}

}

if (status != ERROR) { I2C_GenerateSTART(I2Cxx, ENABLE); time_out = TIME_OUT; while (time_out != (uint32_t) 0) { 8# Check EV5 (is start bit sent?) if (I2C_CheckEvent(I2Cxx, I2C_EVENT_MASTER_MODE_SELECT) == 0) { time_out; if (time_out == 0) { status = ERROR; } } else { time_out = 0; } } }

if (status != ERROR) {

9# Send slave address

I2C_Send7bitAddress(I2Cxx, address, I2C_Direction_Receiver); I2C_SendData(I2Cxx, (address << 1) | 1);

time_out = TIME_OUT; while (time_out != 0) { 10# Check ADDR flag if (I2C_GetFlagStatus(I2Cxx, I2C_FLAG_ADDR) == RESET) { time_out; if (time_out == 0) { status = ERROR; } } else { time_out = 0; } } }

if (status != ERROR) { data[0] = I2C_ReceiveData(I2Cxx); I2C_AcknowledgeConfig(I2Cxx, ENABLE); data[1] = I2C_ReceiveData(I2Cxx);

12# Clear ADDR register by reading SR1 then SR2 register (SR1 has already been read) (void) I2Cxx->SR2;

end = status;

}

9# Generate STOP to terminate the frame I2C_NACKPositionConfig(I2Cxx,I2C_NACKPosition_Current); I2C_GenerateSTOP(I2Cxx, ENABLE); }

Then, then main fonction. The idea is to give to the function a tab and it changes it and fill it with the right data, received from slave device. I put 2 resistor of pull up of 1.5k. I connected them to the pin D1 and i out it in HIGH level.

I think the problem i have is maybe a problem of registers or programming the tabs. U ll find also documents of MAX17205, and screenshots from the oscilloscope.

Thanks a lot for u help im a beginner, i will be really great-full if u can give me an advice.