MQTT - Distance IR Bricklet 2.0

This is the description of the MQTT API bindings for the Distance IR Bricklet 2.0. General information and technical specifications for the Distance IR Bricklet 2.0 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 Distance IR Bricklet 2.0

setup:
    # Get current distance
    subscribe to tinkerforge/response/distance_ir_v2_bricklet/XYZ/get_distance
    publish '' to tinkerforge/request/distance_ir_v2_bricklet/XYZ/get_distance

Callback

Download (example-callback.txt)

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# Change XYZ to the UID of your Distance IR Bricklet 2.0

setup:
    # Handle incoming distance callbacks
    subscribe to tinkerforge/callback/distance_ir_v2_bricklet/XYZ/distance
    publish '{"register": true}' to tinkerforge/register/distance_ir_v2_bricklet/XYZ/distance # Register distance callback
    
    # Set period for distance callback to 1s (1000ms) without a threshold
    publish '{"period": 1000, "value_has_to_change": false, "option": "off", "min": 0, "max": 0}' to tinkerforge/request/distance_ir_v2_bricklet/XYZ/set_distance_callback_configuration

Threshold

Download (example-threshold.txt)

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# Change XYZ to the UID of your Distance IR Bricklet 2.0

setup:
    # Handle incoming distance callbacks
    subscribe to tinkerforge/callback/distance_ir_v2_bricklet/XYZ/distance
    publish '{"register": true}' to tinkerforge/register/distance_ir_v2_bricklet/XYZ/distance # Register distance callback
    
    # Configure threshold for distance "smaller than 30 cm"
    # with a debounce period of 1s (1000ms)
    publish '{"period": 1000, "value_has_to_change": false, "option": "smaller", "min": 300, "max": 0}' to tinkerforge/request/distance_ir_v2_bricklet/XYZ/set_distance_callback_configuration

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/distance_ir_v2_bricklet/<UID>/get_distance
Request:
  • empty payload
Response:
  • distance – Type: int, Range: [0 to 216 - 1]

Returns the distance measured by the sensor. The value is in mm and possible distance ranges are 40 to 300, 100 to 800 and 200 to 1500, depending on the selected IR sensor.

If you want to get the value periodically, it is recommended to use the register/distance_ir_v2_bricklet/<UID>/distance callback. You can set the callback configuration with request/distance_ir_v2_bricklet/<UID>/set_distance_callback_configuration.

request/distance_ir_v2_bricklet/<UID>/get_analog_value
Request:
  • empty payload
Response:
  • analog_value – Type: int, Range: [0 to 232 - 1]

Returns the analog value as read by a analog-to-digital converter. The value has 21 bit with a range of 0 to 2097151.

This is unfiltered raw data. We made sure that the integration time of the ADC is shorter then the measurement interval of the sensor (10ms vs 16.5ms). So there is no information lost.

If you want to do your own calibration or create your own lookup table you can use this value.

If you want to get the value periodically, it is recommended to use the register/distance_ir_v2_bricklet/<UID>/analog_value callback. You can set the callback configuration with request/distance_ir_v2_bricklet/<UID>/set_analog_value_callback_configuration.

request/distance_ir_v2_bricklet/<UID>/set_moving_average_configuration
Request:
  • moving_average_length – Type: int, Range: [0 to 216 - 1]
Response:
  • no response

Sets the length of a moving averaging for the distance.

Setting the length to 1 will turn the averaging off. With less averaging, there is more noise on the data.

The range for the averaging is 1-1000.

New data is gathered every ~10ms. With a moving average of length 1000 the resulting averaging window has a length of approximately 10s. If you want to do long term measurements the longest moving average will give the cleanest results.

The default value is 25.

request/distance_ir_v2_bricklet/<UID>/get_moving_average_configuration
Request:
  • empty payload
Response:
  • moving_average_length – Type: int, Range: [0 to 216 - 1]

Returns the moving average configuration as set by request/distance_ir_v2_bricklet/<UID>/set_moving_average_configuration.

request/distance_ir_v2_bricklet/<UID>/set_distance_led_config
Request:
  • config – Type: int, Range: See symbols
Response:
  • no response

Configures the distance LED to be either turned off, turned on, blink in heartbeat mode or show the distance (brighter = object is nearer).

The default value is 3 (show distance).

The following symbols are available for this function:

For config:

  • "Off" = 0
  • "On" = 1
  • "ShowHeartbeat" = 2
  • "ShowDistance" = 3
request/distance_ir_v2_bricklet/<UID>/get_distance_led_config
Request:
  • empty payload
Response:
  • config – Type: int, Range: See symbols

Returns the LED configuration as set by request/distance_ir_v2_bricklet/<UID>/set_distance_led_config

The following symbols are available for this function:

For config:

  • "Off" = 0
  • "On" = 1
  • "ShowHeartbeat" = 2
  • "ShowDistance" = 3
request/distance_ir_v2_bricklet/<UID>/set_sensor_type
Request:
  • sensor – Type: int, Range: See symbols
Response:
  • no response

Sets the sensor type.

The Bricklet comes configured with the correct sensor type and the type is saved in flash (i.e. the Bricklet retains the information if power is lost).

If you want to change the sensor you can set the type in Brick Viewer, you will likely never need to call this function from your program.

The following symbols are available for this function:

For sensor:

  • "2Y0A41" = 0
  • "2Y0A21" = 1
  • "2Y0A02" = 2
request/distance_ir_v2_bricklet/<UID>/get_sensor_type
Request:
  • empty payload
Response:
  • sensor – Type: int, Range: See symbols

Returns the sensor type as set by request/distance_ir_v2_bricklet/<UID>/set_sensor_type.

The following symbols are available for this function:

For sensor:

  • "2Y0A41" = 0
  • "2Y0A21" = 1
  • "2Y0A02" = 2

Advanced Functions

request/distance_ir_v2_bricklet/<UID>/get_spitfp_error_count
Request:
  • empty payload
Response:
  • error_count_ack_checksum – Type: int, Range: [0 to 232 - 1]
  • error_count_message_checksum – Type: int, Range: [0 to 232 - 1]
  • error_count_frame – Type: int, Range: [0 to 232 - 1]
  • error_count_overflow – Type: int, Range: [0 to 232 - 1]

Returns the error count for the communication between Brick and Bricklet.

The errors are divided into

  • ACK checksum errors,
  • message checksum errors,
  • framing errors and
  • overflow errors.

The errors counts are for errors that occur on the Bricklet side. All Bricks have a similar function that returns the errors on the Brick side.

request/distance_ir_v2_bricklet/<UID>/set_bootloader_mode
Request:
  • mode – Type: int, Range: See symbols
Response:
  • status – Type: int, Range: See symbols

Sets the bootloader mode and returns the status after the requested mode change was instigated.

You can change from bootloader mode to firmware mode and vice versa. A change from bootloader mode to firmware mode will only take place if the entry function, device identifier and CRC are present and correct.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

The following symbols are available for this function:

For mode:

  • "Bootloader" = 0
  • "Firmware" = 1
  • "BootloaderWaitForReboot" = 2
  • "FirmwareWaitForReboot" = 3
  • "FirmwareWaitForEraseAndReboot" = 4

For status:

  • "OK" = 0
  • "InvalidMode" = 1
  • "NoChange" = 2
  • "EntryFunctionNotPresent" = 3
  • "DeviceIdentifierIncorrect" = 4
  • "CRCMismatch" = 5
request/distance_ir_v2_bricklet/<UID>/get_bootloader_mode
Request:
  • empty payload
Response:
  • mode – Type: int, Range: See symbols

Returns the current bootloader mode, see request/distance_ir_v2_bricklet/<UID>/set_bootloader_mode.

The following symbols are available for this function:

For mode:

  • "Bootloader" = 0
  • "Firmware" = 1
  • "BootloaderWaitForReboot" = 2
  • "FirmwareWaitForReboot" = 3
  • "FirmwareWaitForEraseAndReboot" = 4
request/distance_ir_v2_bricklet/<UID>/set_write_firmware_pointer
Request:
  • pointer – Type: int, Range: [0 to 232 - 1]
Response:
  • no response

Sets the firmware pointer for request/distance_ir_v2_bricklet/<UID>/write_firmware. The pointer has to be increased by chunks of size 64. The data is written to flash every 4 chunks (which equals to one page of size 256).

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

request/distance_ir_v2_bricklet/<UID>/write_firmware
Request:
  • data – Type: [int, ...], Length: 64, Range: [0 to 255]
Response:
  • status – Type: int, Range: [0 to 255]

Writes 64 Bytes of firmware at the position as written by request/distance_ir_v2_bricklet/<UID>/set_write_firmware_pointer before. The firmware is written to flash every 4 chunks.

You can only write firmware in bootloader mode.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

request/distance_ir_v2_bricklet/<UID>/set_status_led_config
Request:
  • config – Type: int, Range: See symbols
Response:
  • no response

Sets the status LED configuration. By default the LED shows communication traffic between Brick and Bricklet, it flickers once for every 10 received data packets.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is will show heartbeat by default.

The following symbols are available for this function:

For config:

  • "Off" = 0
  • "On" = 1
  • "ShowHeartbeat" = 2
  • "ShowStatus" = 3
request/distance_ir_v2_bricklet/<UID>/get_status_led_config
Request:
  • empty payload
Response:
  • config – Type: int, Range: See symbols

Returns the configuration as set by request/distance_ir_v2_bricklet/<UID>/set_status_led_config

The following symbols are available for this function:

For config:

  • "Off" = 0
  • "On" = 1
  • "ShowHeartbeat" = 2
  • "ShowStatus" = 3
request/distance_ir_v2_bricklet/<UID>/get_chip_temperature
Request:
  • empty payload
Response:
  • temperature – Type: int, Range: [-215 to 215 - 1]

Returns the temperature in °C as measured inside the microcontroller. The value returned is not the ambient temperature!

The temperature is only proportional to the real temperature and it has bad accuracy. Practically it is only useful as an indicator for temperature changes.

request/distance_ir_v2_bricklet/<UID>/reset
Request:
  • empty payload
Response:
  • no response

Calling this function will reset the Bricklet. All configurations will be lost.

After a reset you have to create new device objects, calling functions on the existing ones will result in undefined behavior!

request/distance_ir_v2_bricklet/<UID>/write_uid
Request:
  • uid – Type: int, Range: [0 to 232 - 1]
Response:
  • no response

Writes a new UID into flash. If you want to set a new UID you have to decode the Base58 encoded UID string into an integer first.

We recommend that you use Brick Viewer to change the UID.

request/distance_ir_v2_bricklet/<UID>/read_uid
Request:
  • empty payload
Response:
  • uid – Type: int, Range: [0 to 232 - 1]

Returns the current UID as an integer. Encode as Base58 to get the usual string version.

request/distance_ir_v2_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
  • hardware_version – Type: [int, ...], Length: 3, Range: [0 to 255]
  • firmware_version – Type: [int, ...], Length: 3, 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' 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 Distance IR 2.0's name in a human readable form.

Callback Configuration Functions

request/distance_ir_v2_bricklet/<UID>/set_distance_callback_configuration
Request:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
  • value_has_to_change – Type: bool, Default: false
  • option – Type: char, Range: See symbols, Default: "x"
  • min – Type: int, Range: [0 to 216 - 1]
  • max – Type: int, Range: [0 to 216 - 1]
Response:
  • no response

The period is the period with which the register/distance_ir_v2_bricklet/<UID>/distance callback is triggered periodically. A value of 0 turns the callback off.

If the value has to change-parameter is set to true, the callback is only triggered after the value has changed. If the value didn't change within the period, the callback is triggered immediately on change.

If it is set to false, the callback is continuously triggered with the period, independent of the value.

It is furthermore possible to constrain the callback with thresholds.

The option-parameter together with min/max sets a threshold for the register/distance_ir_v2_bricklet/<UID>/distance callback.

The following options are possible:

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

If the option is set to 'x' (threshold turned off) the callback is triggered with the fixed period.

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

The following symbols are available for this function:

For option:

  • "Off" = "x"
  • "Outside" = "o"
  • "Inside" = "i"
  • "Smaller" = "<"
  • "Greater" = ">"
request/distance_ir_v2_bricklet/<UID>/get_distance_callback_configuration
Request:
  • empty payload
Response:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
  • value_has_to_change – Type: bool, Default: false
  • option – Type: char, Range: See symbols, Default: "x"
  • min – Type: int, Range: [0 to 216 - 1]
  • max – Type: int, Range: [0 to 216 - 1]

Returns the callback configuration as set by request/distance_ir_v2_bricklet/<UID>/set_distance_callback_configuration.

The following symbols are available for this function:

For option:

  • "Off" = "x"
  • "Outside" = "o"
  • "Inside" = "i"
  • "Smaller" = "<"
  • "Greater" = ">"
request/distance_ir_v2_bricklet/<UID>/set_analog_value_callback_configuration
Request:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
  • value_has_to_change – Type: bool, Default: false
  • option – Type: char, Range: See symbols, Default: "x"
  • min – Type: int, Range: [0 to 232 - 1]
  • max – Type: int, Range: [0 to 232 - 1]
Response:
  • no response

The period is the period with which the register/distance_ir_v2_bricklet/<UID>/analog_value callback is triggered periodically. A value of 0 turns the callback off.

If the value has to change-parameter is set to true, the callback is only triggered after the value has changed. If the value didn't change within the period, the callback is triggered immediately on change.

If it is set to false, the callback is continuously triggered with the period, independent of the value.

It is furthermore possible to constrain the callback with thresholds.

The option-parameter together with min/max sets a threshold for the register/distance_ir_v2_bricklet/<UID>/analog_value callback.

The following options are possible:

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

If the option is set to 'x' (threshold turned off) the callback is triggered with the fixed period.

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

The following symbols are available for this function:

For option:

  • "Off" = "x"
  • "Outside" = "o"
  • "Inside" = "i"
  • "Smaller" = "<"
  • "Greater" = ">"
request/distance_ir_v2_bricklet/<UID>/get_analog_value_callback_configuration
Request:
  • empty payload
Response:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
  • value_has_to_change – Type: bool, Default: false
  • option – Type: char, Range: See symbols, Default: "x"
  • min – Type: int, Range: [0 to 232 - 1]
  • max – Type: int, Range: [0 to 232 - 1]

Returns the callback configuration as set by request/distance_ir_v2_bricklet/<UID>/set_analog_value_callback_configuration.

The following symbols are available for this function:

For option:

  • "Off" = "x"
  • "Outside" = "o"
  • "Inside" = "i"
  • "Smaller" = "<"
  • "Greater" = ">"

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/distance_ir_v2_bricklet/<UID>/distance
Register Request:
  • register – Type: bool
Callback Response:
  • distance – Type: int, Range: [0 to 216 - 1]

A callback can be registered for this event by publishing to the .../register/distance_ir_v2_bricklet/<UID>/distance[/<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/distance_ir_v2_bricklet/<UID>/distance[/<SUFFIX>] topic for each registered suffix.

This callback is triggered periodically according to the configuration set by request/distance_ir_v2_bricklet/<UID>/set_distance_callback_configuration.

The callback payload is the same as request/distance_ir_v2_bricklet/<UID>/get_distance.

register/distance_ir_v2_bricklet/<UID>/analog_value
Register Request:
  • register – Type: bool
Callback Response:
  • analog_value – Type: int, Range: [0 to 232 - 1]

A callback can be registered for this event by publishing to the .../register/distance_ir_v2_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/distance_ir_v2_bricklet/<UID>/analog_value[/<SUFFIX>] topic for each registered suffix.

This callback is triggered periodically according to the configuration set by request/distance_ir_v2_bricklet/<UID>/set_analog_value_callback_configuration.

The callback payload is the same as request/distance_ir_v2_bricklet/<UID>/get_analog_value.