| Kernel driver sht3x |
| =================== |
| |
| Supported chips: |
| |
| * Sensirion SHT3x-DIS |
| |
| Prefix: 'sht3x' |
| |
| Addresses scanned: none |
| |
| Datasheets: |
| - https://sensirion.com/media/documents/213E6A3B/63A5A569/Datasheet_SHT3x_DIS.pdf |
| - https://sensirion.com/media/documents/051DF50B/639C8101/Sensirion_Humidity_and_Temperature_Sensors_Datasheet_SHT33.pdf |
| |
| * Sensirion STS3x-DIS |
| |
| Prefix: 'sts3x' |
| |
| Addresses scanned: none |
| |
| Datasheets: |
| - https://sensirion.com/media/documents/1DA31AFD/61641F76/Sensirion_Temperature_Sensors_STS3x_Datasheet.pdf |
| - https://sensirion.com/media/documents/292A335C/65537BAF/Sensirion_Datasheet_STS32_STS33.pdf |
| |
| Author: |
| |
| - David Frey <david.frey@sensirion.com> |
| - Pascal Sachs <pascal.sachs@sensirion.com> |
| |
| Description |
| ----------- |
| |
| This driver implements support for the Sensirion SHT3x-DIS and STS3x-DIS |
| series of humidity and temperature sensors. 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 (0x4a or 0x4b for sts3x), depending on the wiring. See |
| Documentation/i2c/instantiating-devices.rst for methods to instantiate the |
| device. |
| |
| Even if sht3x sensor supports clock-stretch (blocking mode) and non-stretch |
| (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. |
| |
| The serial number exposed to debugfs allows for unique identification of the |
| sensors. For sts32, sts33 and sht33, the manufacturer provides calibration |
| certificates through an API. |
| |
| 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 |
| =================== ============================================================ |
| |
| debugfs-Interface |
| ----------------- |
| |
| =================== ============================================================ |
| serial_number: unique serial number of the sensor in decimal |
| =================== ============================================================ |
