FXLS8471Q - Accelerometer orientation detection function example code

Hi Everyone,

If you are interested in a simple bare metal example code illustrating the use of the FXLS8471Q orientation detection function, please find below one of my examples I created for the FXLS8471Q accelerometer while working with the NXP FRDM-KL25Z platform and FRDMSTBC-A8471 board.

This example code complements the code snippet from the AN4068.

void FXLS8471Q_Init (void)
{
  FXLS8471Q_WriteRegister(CTRL_REG1, 0x00);  // Standby mode
      
  FXLS8471Q_WriteRegister(PL_CFG_REG, 0x40); // Enable orientation detection
  FXLS8471Q_WriteRegister(PL_BF_ZCOMP_REG, 0x43);  // Back/Front trip point set to 75°, Z-lockout angle set to 25°
  FXLS8471Q_WriteRegister(P_L_THS_REG, 0x14);  // Threshold angle = 45°, hysteresis = 14°
  FXLS8471Q_WriteRegister(PL_COUNT_REG, 0x05); // Debounce counter set to 100ms at 50Hz 
      
  FXLS8471Q_WriteRegister(CTRL_REG3, 0x00);  // Push-pull, active low interrupt
  FXLS8471Q_WriteRegister(CTRL_REG4, 0x10); // Orientation interrupt enabled
  FXLS8471Q_WriteRegister(CTRL_REG5, 0x10); // Route orientation interrupt to INT1 - PTD4
            
  FXLS8471Q_WriteRegister(CTRL_REG1, 0x21); // ODR = 50Hz, Active mode
}‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

In the ISR, only the interrupt flag is cleared and the PL_STATUS (0x10) register is read in order to:

- Clear the SRC_LNDPRT flag in the INT_SOURCE register and deassert the INT1 pin, as shown on the screenshot below.

- Get orientation information. 0x82 in this example corresponds to "Portrait down" orientation.

void PORTD_IRQHandler()
{
  PORTD_PCR4 |= PORT_PCR_ISF_MASK; // Clear the interrupt flag 
  PL_Status = FXLS8471Q_ReadRegister(PL_STATUS_REG); // Read the PL_STATUS register to clear the SRC_LNDPRT flag in the INT_SOURCE register  
}‍‍‍‍‍‍‍‍‍‍

Attached you can find the complete source code. If there are any questions regarding this simple example code, please feel free to ask below.

Regards,

Tomas

FXLS8471Q - Accelerometer orientation detection function example code

FXLS8471Q - Accelerometer orientation detection function example code

FXLS8471Q - Accelerometer orientation detection function example code

Accelerometers