MQTT - Humidity Bricklet

This is the description of the MQTT API bindings for the Humidity Bricklet. General information and technical specifications for the Humidity Bricklet are summarized in its hardware description.

An installation guide for the MQTT API bindings is part of their general description.

Examples

The example code below is Public Domain (CC0 1.0).

Simple

Download (example-simple.txt)

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# Change XYZ to the UID of your Humidity Bricklet

setup:
    # Get current humidity
    subscribe to tinkerforge/response/humidity_bricklet/XYZ/get_humidity
    publish '' to tinkerforge/request/humidity_bricklet/XYZ/get_humidity

Callback

Download (example-callback.txt)

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# Change XYZ to the UID of your Humidity Bricklet

setup:
    # Handle incoming humidity callbacks
    subscribe to tinkerforge/callback/humidity_bricklet/XYZ/humidity
    publish '{"register": true}' to tinkerforge/register/humidity_bricklet/XYZ/humidity # Register humidity callback

    # Set period for humidity callback to 1s (1000ms)
    # Note: The humidity callback is only called every second
    #       if the humidity has changed since the last call!
    publish '{"period": 1000}' to tinkerforge/request/humidity_bricklet/XYZ/set_humidity_callback_period

Threshold

Download (example-threshold.txt)

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# Change XYZ to the UID of your Humidity Bricklet

setup:
    # Get threshold callbacks with a debounce time of 10 seconds (10000ms)
    publish '{"debounce": 10000}' to tinkerforge/request/humidity_bricklet/XYZ/set_debounce_period

    # Handle incoming humidity reached callbacks
    subscribe to tinkerforge/callback/humidity_bricklet/XYZ/humidity_reached
    publish '{"register": true}' to tinkerforge/register/humidity_bricklet/XYZ/humidity_reached # Register humidity_reached callback

    # Configure threshold for humidity "outside of 30 to 60 %RH"
    publish '{"option": "outside", "min": 300, "max": 600}' to tinkerforge/request/humidity_bricklet/XYZ/set_humidity_callback_threshold

API

All published payloads to and from the MQTT bindings are in JSON format.

If an error occures, the bindings publish a JSON object containing the error message as member _ERROR. It is published on the corresponding response topic: .../response/... for .../request/... and .../callback/... for .../register/....

Basic Functions

request/humidity_bricklet/<UID>/get_humidity
Request:
  • empty payload
Response:
  • humidity – Type: int, Unit: 1/10 %, Range: [0 to 1000]

Returns the humidity of the sensor.

If you want to get the humidity periodically, it is recommended to use the register/humidity_bricklet/<UID>/humidity callback and set the period with request/humidity_bricklet/<UID>/set_humidity_callback_period.

Advanced Functions

request/humidity_bricklet/<UID>/get_analog_value
Request:
  • empty payload
Response:
  • value – Type: int, Range: [0 to 212 - 1]

Returns the value as read by a 12-bit analog-to-digital converter.

Note

The value returned by request/humidity_bricklet/<UID>/get_humidity is averaged over several samples to yield less noise, while request/humidity_bricklet/<UID>/get_analog_value gives back raw unfiltered analog values. The returned humidity value is calibrated for room temperatures, if you use the sensor in extreme cold or extreme warm environments, you might want to calculate the humidity from the analog value yourself. See the HIH 5030 datasheet.

If you want the analog value periodically, it is recommended to use the register/humidity_bricklet/<UID>/analog_value callback and set the period with request/humidity_bricklet/<UID>/set_analog_value_callback_period.

request/humidity_bricklet/<UID>/get_identity
Request:
  • empty payload
Response:
  • uid – Type: string, Length: up to 8
  • connected_uid – Type: string, Length: up to 8
  • position – Type: char, Range: ["a" to "h", "i", "z"]
  • hardware_version – Type: [int, ...], Length: 3
    • 0: major – Type: int, Range: [0 to 255]
    • 1: minor – Type: int, Range: [0 to 255]
    • 2: revision – Type: int, Range: [0 to 255]
  • firmware_version – Type: [int, ...], Length: 3
    • 0: major – Type: int, Range: [0 to 255]
    • 1: minor – Type: int, Range: [0 to 255]
    • 2: revision – Type: int, Range: [0 to 255]
  • device_identifier – Type: int, Range: [0 to 216 - 1]
  • _display_name – Type: string

Returns the UID, the UID where the Bricklet is connected to, the position, the hardware and firmware version as well as the device identifier.

The position can be 'a', 'b', 'c', 'd', 'e', 'f', 'g' or 'h' (Bricklet Port). The Raspberry Pi HAT (Zero) Brick is always at position 'i' and the Bricklet connected to an Isolator Bricklet is always as position 'z'.

The device identifier numbers can be found here. If symbolic output is not disabled, the device identifier is mapped to the corresponding name in the format used in topics.

The display name contains the Humidity's name in a human readable form.

Callback Configuration Functions

request/humidity_bricklet/<UID>/set_humidity_callback_period
Request:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Response:
  • no response

Sets the period with which the register/humidity_bricklet/<UID>/humidity callback is triggered periodically. A value of 0 turns the callback off.

The register/humidity_bricklet/<UID>/humidity callback is only triggered if the humidity has changed since the last triggering.

request/humidity_bricklet/<UID>/get_humidity_callback_period
Request:
  • empty payload
Response:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by request/humidity_bricklet/<UID>/set_humidity_callback_period.

request/humidity_bricklet/<UID>/set_analog_value_callback_period
Request:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Response:
  • no response

Sets the period with which the register/humidity_bricklet/<UID>/analog_value callback is triggered periodically. A value of 0 turns the callback off.

The register/humidity_bricklet/<UID>/analog_value callback is only triggered if the analog value has changed since the last triggering.

request/humidity_bricklet/<UID>/get_analog_value_callback_period
Request:
  • empty payload
Response:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by request/humidity_bricklet/<UID>/set_analog_value_callback_period.

request/humidity_bricklet/<UID>/set_humidity_callback_threshold
Request:
  • option – Type: char, Range: See symbols, Default: "x"
  • min – Type: int, Unit: 1/10 %, Range: [0 to 216 - 1], Default: 0
  • max – Type: int, Unit: 1/10 %, Range: [0 to 216 - 1], Default: 0
Response:
  • no response

Sets the thresholds for the register/humidity_bricklet/<UID>/humidity_reached callback.

The following options are possible:

Option Description
'x' Callback is turned off
'o' Callback is triggered when the humidity is outside the min and max values
'i' Callback is triggered when the humidity is inside the min and max values
'<' Callback is triggered when the humidity is smaller than the min value (max is ignored)
'>' Callback is triggered when the humidity is greater than the min value (max is ignored)

The following symbols are available for this function:

For option:

  • "off" = "x"
  • "outside" = "o"
  • "inside" = "i"
  • "smaller" = "<"
  • "greater" = ">"
request/humidity_bricklet/<UID>/get_humidity_callback_threshold
Request:
  • empty payload
Response:
  • option – Type: char, Range: See symbols, Default: "x"
  • min – Type: int, Unit: 1/10 %, Range: [0 to 216 - 1], Default: 0
  • max – Type: int, Unit: 1/10 %, Range: [0 to 216 - 1], Default: 0

Returns the threshold as set by request/humidity_bricklet/<UID>/set_humidity_callback_threshold.

The following symbols are available for this function:

For option:

  • "off" = "x"
  • "outside" = "o"
  • "inside" = "i"
  • "smaller" = "<"
  • "greater" = ">"
request/humidity_bricklet/<UID>/set_analog_value_callback_threshold
Request:
  • option – Type: char, Range: See symbols, Default: "x"
  • min – Type: int, Range: [0 to 216 - 1], Default: 0
  • max – Type: int, Range: [0 to 216 - 1], Default: 0
Response:
  • no response

Sets the thresholds for the register/humidity_bricklet/<UID>/analog_value_reached callback.

The following options are possible:

Option Description
'x' Callback is turned off
'o' Callback is triggered when the analog value is outside the min and max values
'i' Callback is triggered when the analog value is inside the min and max values
'<' Callback is triggered when the analog value is smaller than the min value (max is ignored)
'>' Callback is triggered when the analog value is greater than the min value (max is ignored)

The following symbols are available for this function:

For option:

  • "off" = "x"
  • "outside" = "o"
  • "inside" = "i"
  • "smaller" = "<"
  • "greater" = ">"
request/humidity_bricklet/<UID>/get_analog_value_callback_threshold
Request:
  • empty payload
Response:
  • option – Type: char, Range: See symbols, Default: "x"
  • min – Type: int, Range: [0 to 216 - 1], Default: 0
  • max – Type: int, Range: [0 to 216 - 1], Default: 0

Returns the threshold as set by request/humidity_bricklet/<UID>/set_analog_value_callback_threshold.

The following symbols are available for this function:

For option:

  • "off" = "x"
  • "outside" = "o"
  • "inside" = "i"
  • "smaller" = "<"
  • "greater" = ">"
request/humidity_bricklet/<UID>/set_debounce_period
Request:
  • debounce – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 100
Response:
  • no response

Sets the period with which the threshold callbacks

are triggered, if the thresholds

keep being reached.

request/humidity_bricklet/<UID>/get_debounce_period
Request:
  • empty payload
Response:
  • debounce – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 100

Returns the debounce period as set by request/humidity_bricklet/<UID>/set_debounce_period.

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the corresponding .../register/... topic and an optional suffix. This suffix can be used to deregister the callback later.

Note

Using callbacks for recurring events is always preferred compared to using getters. It will use less USB bandwidth and the latency will be a lot better, since there is no round trip time.

register/humidity_bricklet/<UID>/humidity
Register Request:
  • register – Type: bool
Callback Response:
  • humidity – Type: int, Unit: 1/10 %, Range: [0 to 1000]

A callback can be registered for this event by publishing to the .../register/humidity_bricklet/<UID>/humidity[/<SUFFIX>] topic with the payload "true". An added callback can be removed by publishing to the same topic with the payload "false". To support multiple (de)registrations, e.g. for message filtering, an optional suffix can be used.

If the callback is triggered, a message with it's payload is published under the corresponding .../callback/humidity_bricklet/<UID>/humidity[/<SUFFIX>] topic for each registered suffix.

This callback is triggered periodically with the period that is set by request/humidity_bricklet/<UID>/set_humidity_callback_period. The callback payload is the humidity of the sensor.

The register/humidity_bricklet/<UID>/humidity callback is only triggered if the humidity has changed since the last triggering.

register/humidity_bricklet/<UID>/analog_value
Register Request:
  • register – Type: bool
Callback Response:
  • value – Type: int, Range: [0 to 212 - 1]

A callback can be registered for this event by publishing to the .../register/humidity_bricklet/<UID>/analog_value[/<SUFFIX>] topic with the payload "true". An added callback can be removed by publishing to the same topic with the payload "false". To support multiple (de)registrations, e.g. for message filtering, an optional suffix can be used.

If the callback is triggered, a message with it's payload is published under the corresponding .../callback/humidity_bricklet/<UID>/analog_value[/<SUFFIX>] topic for each registered suffix.

This callback is triggered periodically with the period that is set by request/humidity_bricklet/<UID>/set_analog_value_callback_period. The callback payload is the analog value of the sensor.

The register/humidity_bricklet/<UID>/analog_value callback is only triggered if the humidity has changed since the last triggering.

register/humidity_bricklet/<UID>/humidity_reached
Register Request:
  • register – Type: bool
Callback Response:
  • humidity – Type: int, Unit: 1/10 %, Range: [0 to 1000]

A callback can be registered for this event by publishing to the .../register/humidity_bricklet/<UID>/humidity_reached[/<SUFFIX>] topic with the payload "true". An added callback can be removed by publishing to the same topic with the payload "false". To support multiple (de)registrations, e.g. for message filtering, an optional suffix can be used.

If the callback is triggered, a message with it's payload is published under the corresponding .../callback/humidity_bricklet/<UID>/humidity_reached[/<SUFFIX>] topic for each registered suffix.

This callback is triggered when the threshold as set by request/humidity_bricklet/<UID>/set_humidity_callback_threshold is reached. The callback payload is the humidity of the sensor.

If the threshold keeps being reached, the callback is triggered periodically with the period as set by request/humidity_bricklet/<UID>/set_debounce_period.

register/humidity_bricklet/<UID>/analog_value_reached
Register Request:
  • register – Type: bool
Callback Response:
  • value – Type: int, Range: [0 to 212 - 1]

A callback can be registered for this event by publishing to the .../register/humidity_bricklet/<UID>/analog_value_reached[/<SUFFIX>] topic with the payload "true". An added callback can be removed by publishing to the same topic with the payload "false". To support multiple (de)registrations, e.g. for message filtering, an optional suffix can be used.

If the callback is triggered, a message with it's payload is published under the corresponding .../callback/humidity_bricklet/<UID>/analog_value_reached[/<SUFFIX>] topic for each registered suffix.

This callback is triggered when the threshold as set by request/humidity_bricklet/<UID>/set_analog_value_callback_threshold is reached. The callback payload is the analog value of the sensor.

If the threshold keeps being reached, the callback is triggered periodically with the period as set by request/humidity_bricklet/<UID>/set_debounce_period.