iio/afe/temperature-sense-rtd.yaml

1 # SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
3 ---
4 $id: http://devicetree.org/schemas/iio/afe/temperature-sense-rtd.yaml#
5 $schema: http://devicetree.org/meta-schemas/core.yaml#
10   - Liam Beguin <liambeguin@gmail.com>
17   When an io-channel measures the output voltage across an RTD such as a
25     T = 1 / (alpha * r0 * iexc) * (V - r0 * iexc)
30           -----
32         +---+----+
34         +---+----+
38             +---- Vout
40         +---+----+
42         +---+----+
44           -----
49     const: temperature-sense-rtd
51   io-channels:
54       Channel node of a voltage io-channel.
56   '#io-channel-cells':
59   excitation-current-microamp:
60     description: The current fed through the RTD sensor.
62   alpha-ppm-per-celsius:
64       alpha can also be expressed in micro-ohms per ohm Celsius. It's a linear
68       alpha = (R_100 - R_0) / (100 * R_0)
71       R_0 (or r-naught-ohms) is the resistance of the sensor at 0 degrees
75       and ASTM E-1137 specify an alpha of 3850.
77   r-naught-ohms:
84   - compatible
85   - io-channels
86   - excitation-current-microamp
87   - alpha-ppm-per-celsius
88   - r-naught-ohms
91   - |
92     pt1000_1: temperature-sensor0 {
93         compatible = "temperature-sense-rtd";
94         #io-channel-cells = <0>;
95         io-channels = <&temp_adc1 0>;
97         excitation-current-microamp = <1000>; /* i = U/R = 5 / 5000 */
98         alpha-ppm-per-celsius = <3908>;
99         r-naught-ohms = <1000>;