sht3x.rst 3.5 KB

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  1. Kernel driver sht3x
  2. ===================
  3. Supported chips:
  4. * Sensirion SHT3x-DIS
  5. Prefix: 'sht3x'
  6. Addresses scanned: none
  7. Datasheet: https://www.sensirion.com/file/datasheet_sht3x_digital
  8. Author:
  9. - David Frey <david.frey@sensirion.com>
  10. - Pascal Sachs <pascal.sachs@sensirion.com>
  11. Description
  12. -----------
  13. This driver implements support for the Sensirion SHT3x-DIS chip, a humidity
  14. and temperature sensor. Temperature is measured in degrees celsius, relative
  15. humidity is expressed as a percentage. In the sysfs interface, all values are
  16. scaled by 1000, i.e. the value for 31.5 degrees celsius is 31500.
  17. The device communicates with the I2C protocol. Sensors can have the I2C
  18. addresses 0x44 or 0x45, depending on the wiring. See
  19. Documentation/i2c/instantiating-devices.rst for methods to instantiate the device.
  20. There are two options configurable by means of sht3x_platform_data:
  21. 1. blocking (pull the I2C clock line down while performing the measurement) or
  22. non-blocking mode. Blocking mode will guarantee the fastest result but
  23. the I2C bus will be busy during that time. By default, non-blocking mode
  24. is used. Make sure clock-stretching works properly on your device if you
  25. want to use blocking mode.
  26. 2. high or low accuracy. High accuracy is used by default and using it is
  27. strongly recommended.
  28. The sht3x sensor supports a single shot mode as well as 5 periodic measure
  29. modes, which can be controlled with the update_interval sysfs interface.
  30. The allowed update_interval in milliseconds are as follows:
  31. ===== ======= ====================
  32. 0 single shot mode
  33. 2000 0.5 Hz periodic measurement
  34. 1000 1 Hz periodic measurement
  35. 500 2 Hz periodic measurement
  36. 250 4 Hz periodic measurement
  37. 100 10 Hz periodic measurement
  38. ===== ======= ====================
  39. In the periodic measure mode, the sensor automatically triggers a measurement
  40. with the configured update interval on the chip. When a temperature or humidity
  41. reading exceeds the configured limits, the alert attribute is set to 1 and
  42. the alert pin on the sensor is set to high.
  43. When the temperature and humidity readings move back between the hysteresis
  44. values, the alert bit is set to 0 and the alert pin on the sensor is set to
  45. low.
  46. sysfs-Interface
  47. ---------------
  48. =================== ============================================================
  49. temp1_input: temperature input
  50. humidity1_input: humidity input
  51. temp1_max: temperature max value
  52. temp1_max_hyst: temperature hysteresis value for max limit
  53. humidity1_max: humidity max value
  54. humidity1_max_hyst: humidity hysteresis value for max limit
  55. temp1_min: temperature min value
  56. temp1_min_hyst: temperature hysteresis value for min limit
  57. humidity1_min: humidity min value
  58. humidity1_min_hyst: humidity hysteresis value for min limit
  59. temp1_alarm: alarm flag is set to 1 if the temperature is outside the
  60. configured limits. Alarm only works in periodic measure mode
  61. humidity1_alarm: alarm flag is set to 1 if the humidity is outside the
  62. configured limits. Alarm only works in periodic measure mode
  63. heater_enable: heater enable, heating element removes excess humidity from
  64. sensor:
  65. - 0: turned off
  66. - 1: turned on
  67. update_interval: update interval, 0 for single shot, interval in msec
  68. for periodic measurement. If the interval is not supported
  69. by the sensor, the next faster interval is chosen
  70. =================== ============================================================