MQTT - Voltage/Current Bricklet

This is the description of the MQTT API bindings for the Voltage/Current Bricklet. General information and technical specifications for the Voltage/Current 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 Voltage/Current Bricklet

setup:
    # Get current voltage
    subscribe to tinkerforge/response/voltage_current_bricklet/XYZ/get_voltage
    publish '' to tinkerforge/request/voltage_current_bricklet/XYZ/get_voltage
    
    # Get current current
    subscribe to tinkerforge/response/voltage_current_bricklet/XYZ/get_current
    publish '' to tinkerforge/request/voltage_current_bricklet/XYZ/get_current

Callback

Download (example-callback.txt)

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# Change XYZ to the UID of your Voltage/Current Bricklet

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

Threshold

Download (example-threshold.txt)

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# Change XYZ to the UID of your Voltage/Current Bricklet

setup:
    # Get threshold callbacks with a debounce time of 10 seconds (10000ms)
    publish '{"debounce": 10000}' to tinkerforge/request/voltage-current_bricklet/XYZ/set_debounce_period
    
    # Handle incoming power reached callbacks
    subscribe to tinkerforge/callback/voltage_current_bricklet/XYZ/power_reached
    publish '{"register": true}' to tinkerforge/register/voltage_current_bricklet/XYZ/power_reached # Register power_reached callback
    
    # Configure threshold for power "greater than 10 W"
    publish '{"option": "greater", "min": 10000, "max": 0}' to tinkerforge/request/voltage_current_bricklet/XYZ/set_power_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/voltage_current_bricklet/<UID>/get_current
Response payload:
  • current -- int

Returns the current. The value is in mA and between -20000mA and 20000mA.

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

request/voltage_current_bricklet/<UID>/get_voltage
Response payload:
  • voltage -- int

Returns the voltage. The value is in mV and between 0mV and 36000mV.

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

request/voltage_current_bricklet/<UID>/get_power
Response payload:
  • power -- int

Returns the power. The value is in mW and between 0mV and 720000mW.

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

request/voltage_current_bricklet/<UID>/set_configuration
Request payload:
  • averaging -- int (has symbols)
  • voltage_conversion_time -- int
  • current_conversion_time -- int

Sets the configuration of the Voltage/Current Bricklet. It is possible to configure number of averages as well as voltage and current conversion time.

Averaging:

Value Number of Averages
0 1
1 4
2 16
3 64
4 128
5 256
6 512
>=7 1024

Voltage/Current conversion:

Value Conversion time
0 140µs
1 204µs
2 332µs
3 588µs
4 1.1ms
5 2.116ms
6 4.156ms
>=7 8.244ms

The default values are 3, 4 and 4 (64, 1.1ms, 1.1ms) for averaging, voltage conversion and current conversion.

The following symbols are available for this function:

for averaging:

  • "1" = 0
  • "4" = 1
  • "16" = 2
  • "64" = 3
  • "128" = 4
  • "256" = 5
  • "512" = 6
  • "1024" = 7
request/voltage_current_bricklet/<UID>/get_configuration
Response payload:
  • averaging -- int (has symbols)
  • voltage_conversion_time -- int
  • current_conversion_time -- int

Returns the configuration as set by request/voltage_current_bricklet/<UID>/set_configuration.

The following symbols are available for this function:

for averaging:

  • "1" = 0
  • "4" = 1
  • "16" = 2
  • "64" = 3
  • "128" = 4
  • "256" = 5
  • "512" = 6
  • "1024" = 7

Advanced Functions

request/voltage_current_bricklet/<UID>/set_calibration
Request payload:
  • gain_multiplier -- int
  • gain_divisor -- int

Since the shunt resistor that is used to measure the current is not perfectly precise, it needs to be calibrated by a multiplier and divisor if a very precise reading is needed.

For example, if you are expecting a measurement of 1000mA and you are measuring 1023mA, you can calibrate the Voltage/Current Bricklet by setting the multiplier to 1000 and the divisor to 1023.

request/voltage_current_bricklet/<UID>/get_calibration
Response payload:
  • gain_multiplier -- int
  • gain_divisor -- int

Returns the calibration as set by request/voltage_current_bricklet/<UID>/set_calibration.

request/voltage_current_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 Voltage/Current's name in a human readable form.

Callback Configuration Functions

request/voltage_current_bricklet/<UID>/set_current_callback_period
Request payload:
  • period -- int

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

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

The default value is 0.

request/voltage_current_bricklet/<UID>/get_current_callback_period
Response payload:
  • period -- int

Returns the period as set by request/voltage_current_bricklet/<UID>/set_current_callback_period.

request/voltage_current_bricklet/<UID>/set_voltage_callback_period
Request payload:
  • period -- int

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

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

The default value is 0.

request/voltage_current_bricklet/<UID>/get_voltage_callback_period
Response payload:
  • period -- int

Returns the period as set by request/voltage_current_bricklet/<UID>/set_voltage_callback_period.

request/voltage_current_bricklet/<UID>/set_power_callback_period
Request payload:
  • period -- int

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

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

The default value is 0.

request/voltage_current_bricklet/<UID>/get_power_callback_period
Response payload:
  • period -- int

Returns the period as set by request/voltage_current_bricklet/<UID>/get_power_callback_period.

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

Sets the thresholds for the register/voltage_current_bricklet/<UID>/current_reached callback.

The following options are possible:

Option Description
'x' Callback is turned off
'o' Callback is triggered when the current is outside the min and max values
'i' Callback is triggered when the current is inside the min and max values
'<' Callback is triggered when the current is smaller than the min value (max is ignored)
'>' Callback is triggered when the current 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/voltage_current_bricklet/<UID>/get_current_callback_threshold
Response payload:
  • option -- char (has symbols)
  • min -- int
  • max -- int

Returns the threshold as set by request/voltage_current_bricklet/<UID>/set_current_callback_threshold.

The following symbols are available for this function:

for option:

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

Sets the thresholds for the register/voltage_current_bricklet/<UID>/voltage_reached callback.

The following options are possible:

Option Description
'x' Callback is turned off
'o' Callback is triggered when the voltage is outside the min and max values
'i' Callback is triggered when the voltage is inside the min and max values
'<' Callback is triggered when the voltage is smaller than the min value (max is ignored)
'>' Callback is triggered when the voltage 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/voltage_current_bricklet/<UID>/get_voltage_callback_threshold
Response payload:
  • option -- char (has symbols)
  • min -- int
  • max -- int

Returns the threshold as set by request/voltage_current_bricklet/<UID>/set_voltage_callback_threshold.

The following symbols are available for this function:

for option:

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

Sets the thresholds for the register/voltage_current_bricklet/<UID>/power_reached callback.

The following options are possible:

Option Description
'x' Callback is turned off
'o' Callback is triggered when the power is outside the min and max values
'i' Callback is triggered when the power is inside the min and max values
'<' Callback is triggered when the power is smaller than the min value (max is ignored)
'>' Callback is triggered when the power 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/voltage_current_bricklet/<UID>/get_power_callback_threshold
Response payload:
  • option -- char (has symbols)
  • min -- int
  • max -- int

Returns the threshold as set by request/voltage_current_bricklet/<UID>/set_power_callback_threshold.

The following symbols are available for this function:

for option:

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

Sets the period in ms with which the threshold callbacks

are triggered, if the thresholds

keep being reached.

The default value is 100.

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

Returns the debounce period as set by request/voltage_current_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/voltage_current_bricklet/<UID>/current
Request payload:
  • register -- bool
Response payload:
  • current -- int

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

This callback is triggered periodically with the period that is set by request/voltage_current_bricklet/<UID>/set_current_callback_period. The callback payload is the current of the sensor.

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

register/voltage_current_bricklet/<UID>/voltage
Request payload:
  • register -- bool
Response payload:
  • voltage -- int

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

This callback is triggered periodically with the period that is set by request/voltage_current_bricklet/<UID>/set_voltage_callback_period. The callback payload is the voltage of the sensor.

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

register/voltage_current_bricklet/<UID>/power
Request payload:
  • register -- bool
Response payload:
  • power -- int

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

This callback is triggered periodically with the period that is set by request/voltage_current_bricklet/<UID>/set_power_callback_period. The callback payload is the power of the sensor.

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

register/voltage_current_bricklet/<UID>/current_reached
Request payload:
  • register -- bool
Response payload:
  • current -- int

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

This callback is triggered when the threshold as set by request/voltage_current_bricklet/<UID>/set_current_callback_threshold is reached. The callback payload is the current of the sensor.

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

register/voltage_current_bricklet/<UID>/voltage_reached
Request payload:
  • register -- bool
Response payload:
  • voltage -- int

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

This callback is triggered when the threshold as set by request/voltage_current_bricklet/<UID>/set_voltage_callback_threshold is reached. The callback payload is the voltage of the sensor.

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

register/voltage_current_bricklet/<UID>/power_reached
Request payload:
  • register -- bool
Response payload:
  • power -- int

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

This callback is triggered when the threshold as set by request/voltage_current_bricklet/<UID>/set_power_callback_threshold is reached. The callback payload is the power of the sensor.

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