Documentation/hwmon/sht3x

   1 Kernel driver sht3x
   2 ===================
   3
   4 Supported chips:
   5   * Sensirion SHT3x-DIS
   6     Prefix: 'sht3x'
   7     Addresses scanned: none
   8     Datasheet: http://www.sensirion.com/fileadmin/user_upload/customers/sensirion/Dokumente/Humidity/Sensirion_Humidity_Datasheet_SHT3x_DIS.pdf
   9
  10 Author:
  11   David Frey <david.frey@sensirion.com>
  12   Pascal Sachs <pascal.sachs@sensirion.com>
  13
  14 Description
  15 -----------
  16
  17 This driver implements support for the Sensirion SHT3x-DIS chip, a humidity
  18 and temperature sensor. Temperature is measured in degrees celsius, relative
  19 humidity is expressed as a percentage. In the sysfs interface, all values are
  20 scaled by 1000, i.e. the value for 31.5 degrees celsius is 31500.
  21
  22 The device communicates with the I2C protocol. Sensors can have the I2C
  23 addresses 0x44 or 0x45, depending on the wiring. See
  24 Documentation/i2c/instantiating-devices for methods to instantiate the device.
  25
  26 There are two options configurable by means of sht3x_platform_data:
  27 1. blocking (pull the I2C clock line down while performing the measurement) or
  28    non-blocking mode. Blocking mode will guarantee the fastest result but
  29    the I2C bus will be busy during that time. By default, non-blocking mode
  30    is used. Make sure clock-stretching works properly on your device if you
  31    want to use blocking mode.
  32 2. high or low accuracy. High accuracy is used by default and using it is
  33    strongly recommended.
  34
  35 The sht3x sensor supports a single shot mode as well as 5 periodic measure
  36 modes, which can be controlled with the update_interval sysfs interface.
  37 The allowed update_interval in milliseconds are as follows:
  38   *     0   single shot mode
  39   *  2000   0.5 Hz periodic measurement
  40   *  1000   1   Hz periodic measurement
  41   *   500   2   Hz periodic measurement
  42   *   250   4   Hz periodic measurement
  43   *   100  10   Hz periodic measurement
  44
  45 In the periodic measure mode, the sensor automatically triggers a measurement
  46 with the configured update interval on the chip. When a temperature or humidity
  47 reading exceeds the configured limits, the alert attribute is set to 1 and
  48 the alert pin on the sensor is set to high.
  49 When the temperature and humidity readings move back between the hysteresis
  50 values, the alert bit is set to 0 and the alert pin on the sensor is set to
  51 low.
  52
  53 sysfs-Interface
  54 ---------------
  55
  56 temp1_input:        temperature input
  57 humidity1_input:    humidity input
  58 temp1_max:          temperature max value
  59 temp1_max_hyst:     temperature hysteresis value for max limit
  60 humidity1_max:      humidity max value
  61 humidity1_max_hyst: humidity hysteresis value for max limit
  62 temp1_min:          temperature min value
  63 temp1_min_hyst:     temperature hysteresis value for min limit
  64 humidity1_min:      humidity min value
  65 humidity1_min_hyst: humidity hysteresis value for min limit
  66 temp1_alarm:        alarm flag is set to 1 if the temperature is outside the
  67                     configured limits. Alarm only works in periodic measure mode
  68 humidity1_alarm:    alarm flag is set to 1 if the humidity is outside the
  69                     configured limits. Alarm only works in periodic measure mode
  70 heater_enable:      heater enable, heating element removes excess humidity from
  71                     sensor
  72                         0: turned off
  73                         1: turned on
  74 update_interval:    update interval, 0 for single shot, interval in msec
  75                     for periodic measurement. If the interval is not supported
  76                     by the sensor, the next faster interval is chosen