1.. SPDX-License-Identifier: GPL-2.0-or-later
2
3Kernel driver ChipCap2
4======================
5
6Supported chips:
7
8  * Amphenol CC2D23, CC2D23S, CC2D25, CC2D25S, CC2D33, CC2D33S, CC2D35, CC2D35S
9
10    Prefix: 'chipcap2'
11
12    Addresses scanned: -
13
14    Datasheet: https://www.amphenol-sensors.com/en/telaire/humidity/527-humidity-sensors/3095-chipcap-2
15
16Author:
17
18  - Javier Carrasco <javier.carrasco.cruz@gmail.com>
19
20Description
21-----------
22
23This driver implements support for the Amphenol ChipCap 2, a humidity and
24temperature chip family. Temperature is measured in milli degrees celsius,
25relative humidity is expressed as a per cent mille. The measurement ranges
26are the following:
27
28  - Relative humidity: 0 to 100000 pcm (14-bit resolution)
29  - Temperature: -40000 to +125000 m°C (14-bit resolution)
30
31The device communicates with the I2C protocol and uses the I2C address 0x28
32by default.
33
34Depending on the hardware configuration, up to two humidity alarms to control
35minimum and maximum values are provided. Their thresholds and hystersis can be
36configured via sysfs.
37
38Thresholds and hysteris must be provided as a per cent mille. These values
39might be truncated to match the 14-bit device resolution (6.1 pcm/LSB)
40
41Known Issues
42------------
43
44The driver does not support I2C address and command window length modification.
45
46sysfs-Interface
47---------------
48
49The following list includes the sysfs attributes that the driver always provides,
50their permissions and a short description:
51
52=============================== ======= ========================================
53Name                            Perm    Description
54=============================== ======= ========================================
55temp1_input:                    RO      temperature input
56humidity1_input:                RO      humidity input
57=============================== ======= ========================================
58
59The following list includes the sysfs attributes that the driver may provide
60depending on the hardware configuration:
61
62=============================== ======= ========================================
63Name                            Perm    Description
64=============================== ======= ========================================
65humidity1_min:                  RW      humidity low limit. Measurements under
66                                        this limit trigger a humidity low alarm
67humidity1_max:                  RW      humidity high limit. Measurements above
68                                        this limit trigger a humidity high alarm
69humidity1_min_hyst:             RW      humidity low hystersis
70humidity1_max_hyst:             RW      humidity high hystersis
71humidity1_min_alarm:            RO      humidity low alarm indicator
72humidity1_max_alarm:            RO      humidity high alarm indicator
73=============================== ======= ========================================
74