I'm experimenting with this accelerometer and I'm having some very disputable results while the device is sitting still.
I'm using ST's library code, but I will detail what I am doing here:
h3lis331dl_full_scale_set(&dev_ctx, H3LIS331DL_100g);
h3lis331dl_data_rate_set(&dev_ctx, H3LIS331DL_ODR_1kHz);
h3lis331dl_axis_x_data_set(&dev_ctx, 1);
h3lis331dl_axis_y_data_set(&dev_ctx, 1);
h3lis331dl_axis_z_data_set(&dev_ctx, 1);
while (1) {
/* Read output only if new value is available */
h3lis331dl_reg_t reg;
h3lis331dl_status_reg_get(&dev_ctx, ®.status_reg);
if (reg.status_reg.zyxda) {
/* Read acceleration data */
memset(data_raw_acceleration, 0x00, 3 * sizeof(int16_t));
h3lis331dl_acceleration_raw_get(&dev_ctx, data_raw_acceleration);
acceleration_mg[0] = h3lis331dl_from_fs100_to_mg(data_raw_acceleration[0]);
acceleration_mg[1] = h3lis331dl_from_fs100_to_mg(data_raw_acceleration[1]);
acceleration_mg[2] = h3lis331dl_from_fs100_to_mg(data_raw_acceleration[2]);
serprintf("ax: %4.1f ay:%4.1f az:%4.1f [mg]",
acceleration_mg[0], acceleration_mg[1], acceleration_mg[2]);
HAL_Delay(1000);
}
}
My output is all over the place:
ax: 588.0 ay:-245.0 az:1274.0 [mg]
ax: 0.0 ay:-196.0 az:882.0 [mg]
ax: 931.0 ay:-441.0 az:1715.0 [mg]
ax: 882.0 ay:49.0 az:1372.0 [mg]
ax: 147.0 ay:-98.0 az:980.0 [mg]
ax: 686.0 ay:-245.0 az:980.0 [mg]
ax: 441.0 ay:-1078.0 az:1323.0 [mg]
ax: 98.0 ay:-294.0 az:931.0 [mg]
ax: 490.0 ay:-49.0 az:1176.0 [mg]
ax: 588.0 ay:-196.0 az:1372.0 [mg]
ax: 539.0 ay:-490.0 az:1323.0 [mg]
ax: 637.0 ay:98.0 az:1225.0 [mg]
ax: 49.0 ay:-196.0 az:1568.0 [mg]
ax: 637.0 ay:-196.0 az:1176.0 [mg]
ax: 294.0 ay:49.0 az:1421.0 [mg]
ax: 1029.0 ay:49.0 az:980.0 [mg]
ax: 931.0 ay: 0.0 az:1568.0 [mg]
ax: 490.0 ay:-49.0 az:1274.0 [mg]
ax: 882.0 ay:-98.0 az:1470.0 [mg]
ax: 147.0 ay:-196.0 az:980.0 [mg]
ax: 147.0 ay: 0.0 az:588.0 [mg]
ax: 882.0 ay:-343.0 az:1568.0 [mg]
ax: 490.0 ay:49.0 az:1127.0 [mg]
ax: 539.0 ay:-343.0 az:1421.0 [mg]
ax: 196.0 ay:-98.0 az:980.0 [mg]
1) Sitting flat and still I would expect closer values to 0,0,1000
2) All the values are bouncing around substantially.
Even if I bias out the readings they are still terrible (no code, but I bias for 1000 readings and subtract that from the readings to achieve close to 0,0,1000)
ax_bias: 438.2
ay_bias: -215.6
az_bias: -242.8
ax: 2.8 ay:-617.4 az:1467.8 [mg]
ax: 100.8 ay:117.6 az:1124.8 [mg]
ax: -291.2 ay:-470.4 az:1614.8 [mg]
ax: 100.8 ay:-176.4 az:2202.8 [mg]
ax: -95.2 ay:264.6 az:2055.8 [mg]
ax: 2.8 ay:-176.4 az:1467.8 [mg]
ax: -389.2 ay:117.6 az:1516.8 [mg]
ax: -438.2 ay:-78.4 az:1663.8 [mg]
ax: -536.2 ay:264.6 az:1222.8 [mg]
ax: -438.2 ay:264.6 az:1565.8 [mg]
ax: -144.2 ay:607.6 az:1565.8 [mg]
ax: -193.2 ay:-225.4 az:1222.8 [mg]
ax: -340.2 ay:313.6 az:1369.8 [mg]
ax: -144.2 ay:-29.4 az:1761.8 [mg]
ax: 2.8 ay:-323.4 az:1957.8 [mg]
ax: -242.2 ay:-617.4 az:1271.8 [mg]
ax: 2.8 ay:-127.4 az:1565.8 [mg]
ax: 149.8 ay:19.6 az:1320.8 [mg]
