lsm6dsox sensor data read in polling mode

[JPARK.2]

Hello, support team.

In my test environment, sensor data is read in polling mode at while loop.

Sensor ODR is set to 1667Hz.

So It was expected that sensor data is read every 1/1667sec.

​But it looks like sensor data is read every 1/1873sec.

(During 5 minutes, each sensor datas are read 562,000 times.)

It is much faster than I expected.

Could you check that Am I misunderstood or Do something wrong?

Below is read function, which is called in while loop.

static void motion_data_read(uint8_t index)
{
    axis3bit16_t data_raw_acceleration;
    axis3bit16_t data_raw_angular_rate;
 
    do{
        /* Read acceleration field data */
        lsm6dsox_acceleration_raw_get(&lsm_ctx, data_raw_acceleration.u8bit); 
    }while(0 == memcmp(&motion_data[0], data_raw_acceleration.u8bit, sizeof(uint8_t)*6));
 
    do{
        /* Read angular rate field data */
        lsm6dsox_angular_rate_raw_get(&lsm_ctx, data_raw_angular_rate.u8bit);
    }while(0 == memcmp(&motion_data[3], data_raw_angular_rate.u8bit, sizeof(uint8_t)*6));
    
    motion_data[0] = data_raw_acceleration.i16bit[0];
    motion_data[1] = data_raw_acceleration.i16bit[1];
    motion_data[2] = data_raw_acceleration.i16bit[2];
    motion_data[3] = data_raw_angular_rate.i16bit[0];
    motion_data[4] = data_raw_angular_rate.i16bit[1];
    motion_data[5] = data_raw_angular_rate.i16bit[2];
}

[Eleon BORLINI · Accepted solution]

Hi @Community member​ ,

please note first that the ODR nominally at 1667Hz can differ of about +-2%, so that it can actually be 1700Hz more or less.

1873Hz is a little too fast, but since you are reading the device in asynchronous mode,

To be sure of the actual value of the ODR; you should acquire the data-ready signal (for example with and oscilloscope), and check this interrupt frequency.

To enable the DRDY signal, you have to configure the LSM6DSOX device as follow:

1. Write INT1_CTRL = 01h // Acc data-ready interrupt on INT1

You can refer to the C examples on Github, and especially to the lsm6dsox_read_data_int.c file.

-Eleon