mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-23 01:10:04 +00:00
![JuenKit Yip](/assets/img/avatar_default.png)
Add "repeatability" attribute to sysfs, it could be read or written to control the sensor. Signed-off-by: JuenKit Yip <JuenKit_Yip@hotmail.com> Link: https://lore.kernel.org/r/DB4PR10MB6261B507C7656E3568DA33E39258A@DB4PR10MB6261.EURPRD10.PROD.OUTLOOK.COM [groeck: Fixed multi-line alignment; dropped check of unsigned against < 0] Signed-off-by: Guenter Roeck <linux@roeck-us.net>
88 lines
3.5 KiB
ReStructuredText
88 lines
3.5 KiB
ReStructuredText
Kernel driver sht3x
|
|
===================
|
|
|
|
Supported chips:
|
|
|
|
* Sensirion SHT3x-DIS
|
|
|
|
Prefix: 'sht3x'
|
|
|
|
Addresses scanned: none
|
|
|
|
Datasheet: https://www.sensirion.com/file/datasheet_sht3x_digital
|
|
|
|
Author:
|
|
|
|
- David Frey <david.frey@sensirion.com>
|
|
- Pascal Sachs <pascal.sachs@sensirion.com>
|
|
|
|
Description
|
|
-----------
|
|
|
|
This driver implements support for the Sensirion SHT3x-DIS chip, a humidity
|
|
and temperature sensor. Temperature is measured in degrees celsius, relative
|
|
humidity is expressed as a percentage. In the sysfs interface, all values are
|
|
scaled by 1000, i.e. the value for 31.5 degrees celsius is 31500.
|
|
|
|
The device communicates with the I2C protocol. Sensors can have the I2C
|
|
addresses 0x44 or 0x45, depending on the wiring. See
|
|
Documentation/i2c/instantiating-devices.rst for methods to instantiate the device.
|
|
|
|
Even if sht3x sensor supports clock-strech(blocking mode) and non-strench
|
|
(non-blocking mode) in single-shot mode, this driver only supports the latter.
|
|
|
|
The sht3x sensor supports a single shot mode as well as 5 periodic measure
|
|
modes, which can be controlled with the update_interval sysfs interface.
|
|
The allowed update_interval in milliseconds are as follows:
|
|
|
|
===== ======= ====================
|
|
0 single shot mode
|
|
2000 0.5 Hz periodic measurement
|
|
1000 1 Hz periodic measurement
|
|
500 2 Hz periodic measurement
|
|
250 4 Hz periodic measurement
|
|
100 10 Hz periodic measurement
|
|
===== ======= ====================
|
|
|
|
In the periodic measure mode, the sensor automatically triggers a measurement
|
|
with the configured update interval on the chip. When a temperature or humidity
|
|
reading exceeds the configured limits, the alert attribute is set to 1 and
|
|
the alert pin on the sensor is set to high.
|
|
When the temperature and humidity readings move back between the hysteresis
|
|
values, the alert bit is set to 0 and the alert pin on the sensor is set to
|
|
low.
|
|
|
|
sysfs-Interface
|
|
---------------
|
|
|
|
=================== ============================================================
|
|
temp1_input: temperature input
|
|
humidity1_input: humidity input
|
|
temp1_max: temperature max value
|
|
temp1_max_hyst: temperature hysteresis value for max limit
|
|
humidity1_max: humidity max value
|
|
humidity1_max_hyst: humidity hysteresis value for max limit
|
|
temp1_min: temperature min value
|
|
temp1_min_hyst: temperature hysteresis value for min limit
|
|
humidity1_min: humidity min value
|
|
humidity1_min_hyst: humidity hysteresis value for min limit
|
|
temp1_alarm: alarm flag is set to 1 if the temperature is outside the
|
|
configured limits. Alarm only works in periodic measure mode
|
|
humidity1_alarm: alarm flag is set to 1 if the humidity is outside the
|
|
configured limits. Alarm only works in periodic measure mode
|
|
heater_enable: heater enable, heating element removes excess humidity from
|
|
sensor:
|
|
|
|
- 0: turned off
|
|
- 1: turned on
|
|
update_interval: update interval, 0 for single shot, interval in msec
|
|
for periodic measurement. If the interval is not supported
|
|
by the sensor, the next faster interval is chosen
|
|
repeatability: write or read repeatability, higher repeatability means
|
|
longer measurement duration, lower noise level and
|
|
larger energy consumption:
|
|
|
|
- 0: low repeatability
|
|
- 1: medium repeatability
|
|
- 2: high repeatability
|
|
=================== ============================================================
|