MQTT - PTC Bricklet

This is the description of the MQTT API bindings for the PTC Bricklet. General information and technical specifications for the PTC 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)

1
2
3
4
5
6
# Change XYZ to the UID of your PTC Bricklet

setup:
    # Get current temperature
    subscribe to tinkerforge/response/ptc_bricklet/XYZ/get_temperature
    publish '' to tinkerforge/request/ptc_bricklet/XYZ/get_temperature

Callback

Download (example-callback.txt)

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
# Change XYZ to the UID of your PTC Bricklet

setup:
    # Handle incoming temperature callbacks
    subscribe to tinkerforge/callback/ptc_bricklet/XYZ/temperature
    publish '{"register": true}' to tinkerforge/register/ptc_bricklet/XYZ/temperature # Register temperature callback
    
    # Set period for temperature callback to 1s (1000ms)
    # Note: The temperature callback is only called every second
    #       if the temperature has changed since the last call!
    publish '{"period": 1000}' to tinkerforge/request/ptc_bricklet/XYZ/set_temperature_callback_period

Threshold

Download (example-threshold.txt)

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
# Change XYZ to the UID of your PTC Bricklet

setup:
    # Get threshold callbacks with a debounce time of 10 seconds (10000ms)
    publish '{"debounce": 10000}' to tinkerforge/request/ptc_bricklet/XYZ/set_debounce_period
    
    # Handle incoming temperature reached callbacks
    subscribe to tinkerforge/callback/ptc_bricklet/XYZ/temperature_reached
    publish '{"register": true}' to tinkerforge/register/ptc_bricklet/XYZ/temperature_reached # Register temperature_reached callback
    
    # Configure threshold for temperature "greater than 30 °C"
    publish '{"option": "greater", "min": 3000, "max": 0}' to tinkerforge/request/ptc_bricklet/XYZ/set_temperature_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 attribute "_ERROR". It is published on the corresponding response topic: .../response/... for .../request/... and .../callback/... for .../register/....

Basic Functions

request/ptc_bricklet/<UID>/get_temperature
Response payload:
  • temperature -- int

Returns the temperature of connected sensor. The value has a range of -246 to 849 °C and is given in °C/100, e.g. a value of 4223 means that a temperature of 42.23 °C is measured.

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

request/ptc_bricklet/<UID>/is_sensor_connected
Response payload:
  • connected -- bool

Returns true if the sensor is connected correctly.

If this function returns false, there is either no Pt100 or Pt1000 sensor connected, the sensor is connected incorrectly or the sensor itself is faulty.

request/ptc_bricklet/<UID>/set_wire_mode
Request payload:
  • mode -- int (has symbols)

Sets the wire mode of the sensor. Possible values are 2, 3 and 4 which correspond to 2-, 3- and 4-wire sensors. The value has to match the jumper configuration on the Bricklet.

The default value is 2 = 2-wire.

The following symbols are available for this function:

for mode:

  • "2" = 2
  • "3" = 3
  • "4" = 4
request/ptc_bricklet/<UID>/get_wire_mode
Response payload:
  • mode -- int (has symbols)

Returns the wire mode as set by request/ptc_bricklet/<UID>/set_wire_mode

The following symbols are available for this function:

for mode:

  • "2" = 2
  • "3" = 3
  • "4" = 4

Advanced Functions

request/ptc_bricklet/<UID>/get_resistance
Response payload:
  • resistance -- int

Returns the value as measured by the MAX31865 precision delta-sigma ADC.

The value can be converted with the following formulas:

  • Pt100: resistance = (value * 390) / 32768
  • Pt1000: resistance = (value * 3900) / 32768

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

request/ptc_bricklet/<UID>/set_noise_rejection_filter
Request payload:
  • filter -- int (has symbols)

Sets the noise rejection filter to either 50Hz (0) or 60Hz (1). Noise from 50Hz or 60Hz power sources (including harmonics of the AC power's fundamental frequency) is attenuated by 82dB.

Default value is 0 = 50Hz.

The following symbols are available for this function:

for filter:

  • "50Hz" = 0
  • "60Hz" = 1
request/ptc_bricklet/<UID>/get_noise_rejection_filter
Response payload:
  • filter -- int (has symbols)

Returns the noise rejection filter option as set by request/ptc_bricklet/<UID>/set_noise_rejection_filter

The following symbols are available for this function:

for filter:

  • "50Hz" = 0
  • "60Hz" = 1
request/ptc_bricklet/<UID>/get_identity
Response payload:
  • uid -- string
  • connected_uid -- string
  • position -- char
  • hardware_version -- [int,int,int]
  • firmware_version -- [int,int,int]
  • device_identifier -- int (has symbols)
  • _display_name -- 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' or 'd'.

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 PTC's name in a human readable form.

Callback Configuration Functions

request/ptc_bricklet/<UID>/set_temperature_callback_period
Request payload:
  • period -- int

Sets the period in ms with which the register/ptc_bricklet/<UID>/temperature callback is triggered periodically. A value of 0 turns the callback off.

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

The default value is 0.

request/ptc_bricklet/<UID>/get_temperature_callback_period
Response payload:
  • period -- int

Returns the period as set by request/ptc_bricklet/<UID>/set_temperature_callback_period.

request/ptc_bricklet/<UID>/set_resistance_callback_period
Request payload:
  • period -- int

Sets the period in ms with which the register/ptc_bricklet/<UID>/resistance callback is triggered periodically. A value of 0 turns the callback off.

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

The default value is 0.

request/ptc_bricklet/<UID>/get_resistance_callback_period
Response payload:
  • period -- int

Returns the period as set by request/ptc_bricklet/<UID>/set_resistance_callback_period.

request/ptc_bricklet/<UID>/set_temperature_callback_threshold
Request payload:
  • option -- char (has symbols)
  • min -- int
  • max -- int

Sets the thresholds for the register/ptc_bricklet/<UID>/temperature_reached callback.

The following options are possible:

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

The default value is ('x', 0, 0).

The following symbols are available for this function:

for option:

  • "Off" = 'x'
  • "Outside" = 'o'
  • "Inside" = 'i'
  • "Smaller" = '<'
  • "Greater" = '>'
request/ptc_bricklet/<UID>/get_temperature_callback_threshold
Response payload:
  • option -- char (has symbols)
  • min -- int
  • max -- int

Returns the threshold as set by request/ptc_bricklet/<UID>/set_temperature_callback_threshold.

The following symbols are available for this function:

for option:

  • "Off" = 'x'
  • "Outside" = 'o'
  • "Inside" = 'i'
  • "Smaller" = '<'
  • "Greater" = '>'
request/ptc_bricklet/<UID>/set_resistance_callback_threshold
Request payload:
  • option -- char (has symbols)
  • min -- int
  • max -- int

Sets the thresholds for the register/ptc_bricklet/<UID>/resistance_reached callback.

The following options are possible:

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

The default value is ('x', 0, 0).

The following symbols are available for this function:

for option:

  • "Off" = 'x'
  • "Outside" = 'o'
  • "Inside" = 'i'
  • "Smaller" = '<'
  • "Greater" = '>'
request/ptc_bricklet/<UID>/get_resistance_callback_threshold
Response payload:
  • option -- char (has symbols)
  • min -- int
  • max -- int

Returns the threshold as set by request/ptc_bricklet/<UID>/set_resistance_callback_threshold.

The following symbols are available for this function:

for option:

  • "Off" = 'x'
  • "Outside" = 'o'
  • "Inside" = 'i'
  • "Smaller" = '<'
  • "Greater" = '>'
request/ptc_bricklet/<UID>/set_debounce_period
Request payload:
  • debounce -- int

Sets the period in ms with which the threshold callback

is triggered, if the threshold

keeps being reached.

The default value is 100.

request/ptc_bricklet/<UID>/get_debounce_period
Response payload:
  • debounce -- int

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

request/ptc_bricklet/<UID>/set_sensor_connected_callback_configuration
Request payload:
  • enabled -- bool

If you enable this callback, the register/ptc_bricklet/<UID>/sensor_connected callback is triggered every time a Pt sensor is connected/disconnected.

By default this callback is disabled.

New in version 2.0.2 (Plugin).

request/ptc_bricklet/<UID>/get_sensor_connected_callback_configuration
Response payload:
  • enabled -- bool

Returns the configuration as set by request/ptc_bricklet/<UID>/set_sensor_connected_callback_configuration.

New in version 2.0.2 (Plugin).

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/ptc_bricklet/<UID>/temperature
Request payload:
  • register -- bool
Response payload:
  • temperature -- int

A callback can be registered for this event by publishing to the .../register/ptc_bricklet/<UID>/temperature[/<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/ptc_bricklet/<UID>/temperature[/<SUFFIX>] topic for each registered suffix.

This callback is triggered periodically with the period that is set by request/ptc_bricklet/<UID>/set_temperature_callback_period. The callback payload is the temperature of the connected sensor.

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

register/ptc_bricklet/<UID>/temperature_reached
Request payload:
  • register -- bool
Response payload:
  • temperature -- int

A callback can be registered for this event by publishing to the .../register/ptc_bricklet/<UID>/temperature_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/ptc_bricklet/<UID>/temperature_reached[/<SUFFIX>] topic for each registered suffix.

This callback is triggered when the threshold as set by request/ptc_bricklet/<UID>/set_temperature_callback_threshold is reached. The callback payload is the temperature of the connected sensor.

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

register/ptc_bricklet/<UID>/resistance
Request payload:
  • register -- bool
Response payload:
  • resistance -- int

A callback can be registered for this event by publishing to the .../register/ptc_bricklet/<UID>/resistance[/<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/ptc_bricklet/<UID>/resistance[/<SUFFIX>] topic for each registered suffix.

This callback is triggered periodically with the period that is set by request/ptc_bricklet/<UID>/set_resistance_callback_period. The callback payload is the resistance of the connected sensor.

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

register/ptc_bricklet/<UID>/resistance_reached
Request payload:
  • register -- bool
Response payload:
  • resistance -- int

A callback can be registered for this event by publishing to the .../register/ptc_bricklet/<UID>/resistance_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/ptc_bricklet/<UID>/resistance_reached[/<SUFFIX>] topic for each registered suffix.

This callback is triggered when the threshold as set by request/ptc_bricklet/<UID>/set_resistance_callback_threshold is reached. The callback payload is the resistance of the connected sensor.

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

register/ptc_bricklet/<UID>/sensor_connected
Request payload:
  • register -- bool
Response payload:
  • connected -- bool

A callback can be registered for this event by publishing to the .../register/ptc_bricklet/<UID>/sensor_connected[/<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/ptc_bricklet/<UID>/sensor_connected[/<SUFFIX>] topic for each registered suffix.

This callback is triggered periodically according to the configuration set by request/ptc_bricklet/<UID>/set_sensor_connected_callback_configuration.

The callback payload is the same as request/ptc_bricklet/<UID>/is_sensor_connected.

New in version 2.0.2 (Plugin).