Brick MQTT Proxy (Discontinued)¶

Examples¶

In the following examples we use mosquitto as broker and client. Other broker and clients can be used similarly. To install the broker and client software under Linux do the following:

sudo apt-get install mosquitto mosquitto-clients

Afterwards start the Brick MQTT Proxy and execute the following examples. The structure is described below. Keep in mind to change the UID in the path to that of your Bricklet.

# enumerate all available devices
mosquitto_sub -v -t tinkerforge/enumerate/available/#

# enumerate all available Laser Range Finder Bricklets
mosquitto_sub -v -t tinkerforge/enumerate/available/bricklet/laser_range_finder

# enable laser
mosquitto_pub -t tinkerforge/bricklet/laser_range_finder/vbM/enable_laser/set -m ''

# get distance
mosquitto_sub -v -t tinkerforge/bricklet/laser_range_finder/vbM/distance

# enumerate all available Analog Out 2.0 Bricklets
mosquitto_sub -v -t tinkerforge/enumerate/available/bricklet/analog_out_v2

# get input voltage
mosquitto_sub -v -t tinkerforge/bricklet/analog_out_v2/7xwQ9g/input_voltage

# get output voltage
mosquitto_sub -v -t tinkerforge/bricklet/analog_out_v2/7xwQ9g/output_voltage

# set output voltage to 2.5V
mosquitto_pub -t tinkerforge/bricklet/analog_out_v2/7xwQ9g/input_voltage -m '{"voltage":2500}'

Devices¶

The proxy publishes retained messages about value and configuration changes of supported devices on topics with the following pattern:

tinkerforge/<prefix>/<uid>/<suffix>

For example, for a Temperature Bricklet with UID XYZ the temperature value is published on:

tinkerforge/bricklet/temperature/XYZ/temperature

The value and configuration information is represented in JSON with the following format:

{
  "_timestamp": <timestamp>,
  "<key>": <value>
}

All messages published by the proxy include a UNIX timestamp to indicate the age of the provided information. The naming and meaning of the key-value pairs matches the payload definition of our TCP/IP protocol. All key-value pairs added by the proxy start with an underscore to avoid name collisions. For example, for a Temperature Bricklet with UID XYZ the temperature value is published as:

{
  "_timestamp": 1440083842.785104,
  "temperature": 2343
}

The proxy subscribes to topics ending in /set allows you to change the configuration of a device. For example, to change the configuration of an Ambient Light Bricklet 2.0 with UID ABC the following JSON payload:

{
  "illuminance_range": 1,
  "integration_time": 2
}

Can be published to this topic:

tinkerforge/bricklet/ambient_light_v2/ABC/configuration/set

The proxy parse the payload and call the configuration setter accordingly.

Again, the naming and meaning of the key-value pairs matches the payload definition of our TCP/IP protocol. In this case the illuminance range is set to 32000lux and the integration time is set to 150ms.

Enumerate¶

There are three major enumerate/ subtopics the proxy will publish enumerate events on:

• tinkerforge/enumerate/available/<device-topic-prefix>: If the list of available devices with a matching topic prefix changes then a retained message with the updated list of all now available devices is published.

• tinkerforge/enumerate/connected/<device-topic-prefix>: If a new device with a matching topic prefix gets connected then a message with information about the connected device is published.

• tinkerforge/enumerate/disconnected/<device-topic-prefix>: If a known device with a matching topic prefix gets disconnected then a message with information about the disconnected device is published.

For example, if an LCD 20x4 Bricklet gets connected then this is published on:

tinkerforge/enumerate/connected/bricklet/lcd_20x4

Also, the retained message on tinkerforge/enumerate/available/bricklet/lcd_20x4 is updated. The device information is represented in JSON for all subtopics with the following format:

{
  "_timestamp": <timestamp>,
  "uid": "<uid>",
  "connected_uid": "<connected_uid>",
  "position": "<position>",
  "hardware_version": [<major>, <minor>, <release>],
  "firmware_version": [<major>, <minor>, <release>],
  "device_identifier": <device_identifier>
}

For a Temperature Bricklet it looks like this:

{
  "_timestamp": 1440143404.176469,
  "uid": "se3",
  "connected_uid": "5VihSm",
  "position": "c",
  "hardware_version": [1, 1, 0],
  "firmware_version": [2, 0, 3],
  "device_identifier": 216
}