FXLS8471Q i2c communication sample

[piotrrosenbaum]

Hi !

I Can't communicate with FXLS8471Q via i2c. I want to read WHO_I_AM register but device don't respond.

After read who value is 255. Can You show me a example code how to read it ?

#define FXLS8471Q_SLAVE_ADDR       0x1E 
#define FXLS8471Q_WHOAMI     0x0D

void FXLS_init(void) {
    uint8_t who;
    Soft_I2C1_send_address(FXLS8471Q_SLAVE_ADDR);
    Soft_I2C1_send_data(FXLS8471Q_WHOAMI, END);
    Soft_I2C1_send_address(FXLS8471Q_SLAVE_ADDR);
    Soft_I2C1_send_data(0x00, END);
    who = Soft_I2C1_read_data(END);
}

[TomasVaverka · Accepted solution]

Hi Piotr,

Here is an example code to read the WHO_AM_I register (0x0D) using I²C when SA0 = SA1 = 0.

//FXLS8471Q 7-bit I2C address
#define FXLS8471Q_I2C_ADDRESS   0x1E // SA0 pin = SA1 = 0 -> 7-bit I2C address is 0x1E 

who_am_i = I2C_ReadRegister(FXLS8471Q_I2C_ADDRESS, 0x0D);

unsigned char I2C_ReadRegister(unsigned char u8SlaveAddress, unsigned char u8RegisterAddress)
{
  unsigned char result;
  I2C_Start();          
  I2C0_D = u8SlaveAddress << 1; /* Send I2C device address with W/R bit = 0 */
  I2C_Wait();
  I2C0_D = u8RegisterAddress; /* Send register address */
  I2C_Wait();
  I2C_RepeatedStart();
  I2C0_D = (u8SlaveAddress << 1) | 0x01; /* Send I2C device address this time with W/R bit = 1 */ 
  I2C_Wait();
  I2C_EnterRxMode();
  I2C_DisableAck();
  result = I2C0_D;
  I2C_Wait();
  I2C_Stop();  
  result = I2C0_D;
  Pause(50);
  return result;
}

A copy from the data sheet:

I hope it helps.

Regards,

Tomas

PS: If my answer helps to solve your question, please mark it as "Correct". Thank you.