xref: /linux/Documentation/ABI/testing/sysfs-bus-iio-isl29501 (revision 3eb66e91a25497065c5322b1268cbc3953642227)
1*1c287992SMathieu OthaceheWhat:		/sys/bus/iio/devices/iio:deviceX/in_proximity0_agc_gain
2*1c287992SMathieu OthaceheWhat:		/sys/bus/iio/devices/iio:deviceX/in_proximity0_agc_gain_bias
3*1c287992SMathieu OthaceheKernelVersion:	4.18
4*1c287992SMathieu OthaceheContact:	linux-iio@vger.kernel.org
5*1c287992SMathieu OthaceheDescription:
6*1c287992SMathieu Othacehe		This sensor has an automatic gain control (agc) loop
7*1c287992SMathieu Othacehe		which sets the analog signal levels at an optimum
8*1c287992SMathieu Othacehe		level by controlling programmable gain amplifiers. The
9*1c287992SMathieu Othacehe		criteria for optimal gain is determined by the sensor.
10*1c287992SMathieu Othacehe
11*1c287992SMathieu Othacehe		Return the actual gain value as an integer in [0; 65536]
12*1c287992SMathieu Othacehe		range when read from.
13*1c287992SMathieu Othacehe
14*1c287992SMathieu Othacehe		The agc gain read when measuring crosstalk shall be
15*1c287992SMathieu Othacehe		written into in_proximity0_agc_gain_bias.
16*1c287992SMathieu Othacehe
17*1c287992SMathieu OthaceheWhat:		/sys/bus/iio/devices/iio:deviceX/in_proximity0_calib_phase_temp_a
18*1c287992SMathieu OthaceheWhat:		/sys/bus/iio/devices/iio:deviceX/in_proximity0_calib_phase_temp_b
19*1c287992SMathieu OthaceheWhat:		/sys/bus/iio/devices/iio:deviceX/in_proximity0_calib_phase_light_a
20*1c287992SMathieu OthaceheWhat:		/sys/bus/iio/devices/iio:deviceX/in_proximity0_calib_phase_light_b
21*1c287992SMathieu OthaceheKernelVersion:	4.18
22*1c287992SMathieu OthaceheContact:	linux-iio@vger.kernel.org
23*1c287992SMathieu OthaceheDescription:
24*1c287992SMathieu Othacehe		The sensor is able to perform correction of distance
25*1c287992SMathieu Othacehe		measurements due to changing temperature and ambient
26*1c287992SMathieu Othacehe		light conditions. It can be programmed to correct for
27*1c287992SMathieu Othacehe		a second order error polynomial.
28*1c287992SMathieu Othacehe
29*1c287992SMathieu Othacehe		Phase data has to be collected when temperature and
30*1c287992SMathieu Othacehe		ambient light are modulated independently.
31*1c287992SMathieu Othacehe
32*1c287992SMathieu Othacehe		Then a least squares curve fit to a second order
33*1c287992SMathieu Othacehe		polynomial has to be generated from the data. The
34*1c287992SMathieu Othacehe		resultant curves have the form ax^2 + bx + c.
35*1c287992SMathieu Othacehe
36*1c287992SMathieu Othacehe		From those two curves, a and b coefficients shall be
37*1c287992SMathieu Othacehe		stored in in_proximity0_calib_phase_temp_a and
38*1c287992SMathieu Othacehe		in_proximity0_calib_phase_temp_b for temperature and
39*1c287992SMathieu Othacehe		in in_proximity0_calib_phase_light_a and
40*1c287992SMathieu Othacehe		in_proximity0_calib_phase_light_b for ambient light.
41*1c287992SMathieu Othacehe
42*1c287992SMathieu Othacehe		Those values must be integer in [0; 8355840] range.
43*1c287992SMathieu Othacehe
44*1c287992SMathieu Othacehe		Finally, the c constant is set by the sensor
45*1c287992SMathieu Othacehe		internally.
46*1c287992SMathieu Othacehe
47*1c287992SMathieu Othacehe		The value stored in sensor is displayed when read from.
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