mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-15 16:24:13 +08:00
ccf988b66d
Convert each file at I2C subsystem, renaming them to .rst and adding to the driver-api book. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Acked-by: Wolfram Sang <wsa@the-dreams.de> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
89 lines
3.5 KiB
ReStructuredText
89 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.
|
|
|
|
There are two options configurable by means of sht3x_platform_data:
|
|
|
|
1. blocking (pull the I2C clock line down while performing the measurement) or
|
|
non-blocking mode. Blocking mode will guarantee the fastest result but
|
|
the I2C bus will be busy during that time. By default, non-blocking mode
|
|
is used. Make sure clock-stretching works properly on your device if you
|
|
want to use blocking mode.
|
|
2. high or low accuracy. High accuracy is used by default and using it is
|
|
strongly recommended.
|
|
|
|
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
|
|
=================== ============================================================
|