TS-7990 STM Magnetometer

This board includes an ST IIS2MDCTR 3-axis magnetometer, which has a magnetic field dynamic range of ±50 gauss (16 bits of precision at up to 150 Hz).

The magnetometer is accessed through Linux's industrial I/O (IIO) subsystem as iis2mdc with channels:

• magn_x
• magn_y
• magn_z
• timestamp

For example:

root@tsimx6ul:~# iio_attr -c iis2mdc -c magn_x
dev 'lis2mdl_magn', channel 'magn_x' (input), attr 'raw', value '630'
dev 'lis2mdl_magn', channel 'magn_x' (input), attr 'scale', value '0.001500'
root@tsimx6ul:~# iio_attr -c iis2mdc -c magn_y
dev 'lis2mdl_magn', channel 'magn_y' (input), attr 'raw', value '-165'
dev 'lis2mdl_magn', channel 'magn_y' (input), attr 'scale', value '0.001500'
root@tsimx6ul:~# iio_attr -c iis2mdc -c magn_z
dev 'lis2mdl_magn', channel 'magn_z' (input), attr 'raw', value '9'
dev 'lis2mdl_magn', channel 'magn_z' (input), attr 'scale', value '0.001500'

Note:

The 5.10 LTS kernel did not have the same "iis2mdc" driver, but uses a drop in under the name "lis2mdl". use this as the device name on 5.10 instead.

This shows a snapshot of the x, y, z values. To get the measured field strength along each axis, multiply the scale by the raw value to get the actual reading in milligauss. In the above example:

• X: 0.945 mG (milligauss)
• Y: -0.2475 mG
• Z: 0.0135 mG