MQTT - Accelerometer Bricklet 2.0

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

1
2
3
4
5
6
# Change XYZ to the UID of your Accelerometer Bricklet 2.0

setup:
    # Get current acceleration
    subscribe to tinkerforge/response/accelerometer_v2_bricklet/XYZ/get_acceleration
    publish '' to tinkerforge/request/accelerometer_v2_bricklet/XYZ/get_acceleration

Callback

Download (example-callback.txt)

1
2
3
4
5
6
7
8
9
# Change XYZ to the UID of your Accelerometer Bricklet 2.0

setup:
    # Handle incoming acceleration callbacks
    subscribe to tinkerforge/callback/accelerometer_v2_bricklet/XYZ/acceleration
    publish '{"register": true}' to tinkerforge/register/accelerometer_v2_bricklet/XYZ/acceleration # Register acceleration callback
    
    # Set period for acceleration callback to 1s (1000ms)
    publish '{"period": 1000, "value_has_to_change": false}' to tinkerforge/request/accelerometer_v2_bricklet/XYZ/set_acceleration_callback_configuration

API

All published payload to an from the MQTT bindings is in the 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/accelerometer_v2_bricklet/<UID>/get_acceleration
Response payload:
 
  • x -- int
  • y -- int
  • z -- int

Returns the acceleration in x, y and z direction. The values are given in g/10000 (1g = 9.80665m/s²), not to be confused with grams.

If you want to get the acceleration periodically, it is recommended to use the register/accelerometer_v2_bricklet/<UID>/acceleration callback and set the period with request/accelerometer_v2_bricklet/<UID>/set_acceleration_callback_configuration.

request/accelerometer_v2_bricklet/<UID>/set_configuration
Request payload:
 
  • data_rate -- int (has symbols)
  • full_scale -- int (has symbols)

Configures the data rate and full scale range. Possible values are:

  • Data rate of 0.781Hz to 25600Hz.
  • Full scale range of -2g to +2g up to -8g to +8g.

Decreasing data rate or full scale range will also decrease the noise on the data.

The default values are 100Hz data rate and -2g to +2g range.

The following symbols are available for this function:

for data_rate:

  • "0781Hz" = 0
  • "1563Hz" = 1
  • "3125Hz" = 2
  • "62512Hz" = 3
  • "125Hz" = 4
  • "25Hz" = 5
  • "50Hz" = 6
  • "100Hz" = 7
  • "200Hz" = 8
  • "400Hz" = 9
  • "800Hz" = 10
  • "1600Hz" = 11
  • "3200Hz" = 12
  • "6400Hz" = 13
  • "12800Hz" = 14
  • "25600Hz" = 15

for full_scale:

  • "2g" = 0
  • "4g" = 1
  • "8g" = 2
request/accelerometer_v2_bricklet/<UID>/get_configuration
Response payload:
 
  • data_rate -- int (has symbols)
  • full_scale -- int (has symbols)

Returns the configuration as set by request/accelerometer_v2_bricklet/<UID>/set_configuration.

The following symbols are available for this function:

for data_rate:

  • "0781Hz" = 0
  • "1563Hz" = 1
  • "3125Hz" = 2
  • "62512Hz" = 3
  • "125Hz" = 4
  • "25Hz" = 5
  • "50Hz" = 6
  • "100Hz" = 7
  • "200Hz" = 8
  • "400Hz" = 9
  • "800Hz" = 10
  • "1600Hz" = 11
  • "3200Hz" = 12
  • "6400Hz" = 13
  • "12800Hz" = 14
  • "25600Hz" = 15

for full_scale:

  • "2g" = 0
  • "4g" = 1
  • "8g" = 2
request/accelerometer_v2_bricklet/<UID>/set_info_led_config
Request payload:
 
  • config -- int (has symbols)

Configures the info LED (marked as "Force" on the Bricklet) to be either turned off, turned on, or blink in heartbeat mode.

The following symbols are available for this function:

for config:

  • "Off" = 0
  • "On" = 1
  • "ShowHeartbeat" = 2
request/accelerometer_v2_bricklet/<UID>/get_info_led_config
Response payload:
 
  • config -- int (has symbols)

Returns the LED configuration as set by request/accelerometer_v2_bricklet/<UID>/set_info_led_config

The following symbols are available for this function:

for config:

  • "Off" = 0
  • "On" = 1
  • "ShowHeartbeat" = 2
request/accelerometer_v2_bricklet/<UID>/set_continuous_acceleration_configuration
Request payload:
 
  • enable_x -- bool
  • enable_y -- bool
  • enable_z -- bool
  • resolution -- int (has symbols)

For high throughput of acceleration data (> 1000Hz) you have to use the register/accelerometer_v2_bricklet/<UID>/continuous_acceleration_16_bit or register/accelerometer_v2_bricklet/<UID>/continuous_acceleration_8_bit callbacks.

You can enable the callback for each axis (x, y, z) individually and choose a resolution of 8 bit or 16 bit.

If at least one of the axis is enabled and the resolution is set to 8 bit, the register/accelerometer_v2_bricklet/<UID>/continuous_acceleration_8_bit callback is activated. If at least one of the axis is enabled and the resolution is set to 16 bit, the register/accelerometer_v2_bricklet/<UID>/continuous_acceleration_16_bit callback is activated.

If a resolution of 8 bit is used, only the 8 most significant bits will be transferred. This means that the unit changes from g/10000 to g*256/10000.

If no axis is enabled, both callbacks are disabled. If one of the continuous callbacks is enabled, the register/accelerometer_v2_bricklet/<UID>/acceleration callback is disabled.

The maximum throughput depends on the exact configuration:

Number of axis enabled Throughput 8 bit Throughout 16 bit
1 25600Hz 25600Hz
2 25600Hz 15000Hz
3 20000Hz 10000Hz

The following symbols are available for this function:

for resolution:

  • "8bit" = 0
  • "16bit" = 1
request/accelerometer_v2_bricklet/<UID>/get_continuous_acceleration_configuration
Response payload:
 
  • enable_x -- bool
  • enable_y -- bool
  • enable_z -- bool
  • resolution -- int (has symbols)

Returns the continuous acceleration configuration as set by request/accelerometer_v2_bricklet/<UID>/set_continuous_acceleration_configuration.

The following symbols are available for this function:

for resolution:

  • "8bit" = 0
  • "16bit" = 1

Advanced Functions

request/accelerometer_v2_bricklet/<UID>/get_spitfp_error_count
Response payload:
 
  • error_count_ack_checksum -- int
  • error_count_message_checksum -- int
  • error_count_frame -- int
  • error_count_overflow -- int

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/accelerometer_v2_bricklet/<UID>/set_bootloader_mode
Request payload:
 
  • mode -- int (has symbols)
Response payload:
 
  • status -- int (has 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/accelerometer_v2_bricklet/<UID>/get_bootloader_mode
Response payload:
 
  • mode -- int (has symbols)

Returns the current bootloader mode, see request/accelerometer_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/accelerometer_v2_bricklet/<UID>/set_write_firmware_pointer
Request payload:
 
  • pointer -- int

Sets the firmware pointer for request/accelerometer_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/accelerometer_v2_bricklet/<UID>/write_firmware
Request payload:
 
  • data -- [int,... (x64)]
Response payload:
 
  • status -- int

Writes 64 Bytes of firmware at the position as written by request/accelerometer_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/accelerometer_v2_bricklet/<UID>/set_status_led_config
Request payload:
 
  • config -- int (has symbols)

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/accelerometer_v2_bricklet/<UID>/get_status_led_config
Response payload:
 
  • config -- int (has symbols)

Returns the configuration as set by request/accelerometer_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/accelerometer_v2_bricklet/<UID>/get_chip_temperature
Response payload:
 
  • temperature -- int

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/accelerometer_v2_bricklet/<UID>/reset

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/accelerometer_v2_bricklet/<UID>/write_uid
Request payload:
 
  • uid -- int

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/accelerometer_v2_bricklet/<UID>/read_uid
Response payload:
 
  • uid -- int

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

request/accelerometer_v2_bricklet/<UID>/get_identity
Response payload:
 
  • uid -- string
  • connected_uid -- string
  • position -- string
  • 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 Accelerometer 2.0's name in a human readable form.

Callback Configuration Functions

request/accelerometer_v2_bricklet/<UID>/set_acceleration_callback_configuration
Request payload:
 
  • period -- int
  • value_has_to_change -- bool

The period in ms is the period with which the register/accelerometer_v2_bricklet/<UID>/acceleration 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.

If this callback is enabled, the register/accelerometer_v2_bricklet/<UID>/continuous_acceleration_16_bit callback and register/accelerometer_v2_bricklet/<UID>/continuous_acceleration_8_bit callback will automatically be disabled.

The default value is (0, false).

request/accelerometer_v2_bricklet/<UID>/get_acceleration_callback_configuration
Response payload:
 
  • period -- int
  • value_has_to_change -- bool

Returns the callback configuration as set by request/accelerometer_v2_bricklet/<UID>/set_acceleration_callback_configuration.

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/accelerometer_v2_bricklet/<UID>/acceleration
Request payload:
 
  • register -- bool
Response payload:
 
  • x -- int
  • y -- int
  • z -- int

A callback can be registered for this event by publishing to the .../register/accelerometer_v2_bricklet/<UID>/acceleration[/<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/accelerometer_v2_bricklet/<UID>/acceleration[/<SUFFIX>] topic for each registered suffix.

This callback is triggered periodically according to the configuration set by request/accelerometer_v2_bricklet/<UID>/set_acceleration_callback_configuration.

The callback payload members are the same as request/accelerometer_v2_bricklet/<UID>/get_acceleration.

register/accelerometer_v2_bricklet/<UID>/continuous_acceleration_16_bit
Request payload:
 
  • register -- bool
Response payload:
 
  • acceleration -- [int,... (x30)]

A callback can be registered for this event by publishing to the .../register/accelerometer_v2_bricklet/<UID>/continuous_acceleration_16_bit[/<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/accelerometer_v2_bricklet/<UID>/continuous_acceleration_16_bit[/<SUFFIX>] topic for each registered suffix.

Returns 30 acceleration values with 16 bit resolution. The data rate can be configured with request/accelerometer_v2_bricklet/<UID>/set_configuration and this callback can be enabled with request/accelerometer_v2_bricklet/<UID>/set_continuous_acceleration_configuration.

The unit of the values is g/10000.

The data is formated in the sequence "x, y, z, x, y, z, ..." depending on the enabled axis. Examples:

  • x, y, z enabled: "x, y, z, ... 10x ..., x, y, z"
  • x, z enabled: "x, z, ... 15x ..., x, z"
  • y enabled: "y, ... 30x ..., y"
register/accelerometer_v2_bricklet/<UID>/continuous_acceleration_8_bit
Request payload:
 
  • register -- bool
Response payload:
 
  • acceleration -- [int,... (x60)]

A callback can be registered for this event by publishing to the .../register/accelerometer_v2_bricklet/<UID>/continuous_acceleration_8_bit[/<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/accelerometer_v2_bricklet/<UID>/continuous_acceleration_8_bit[/<SUFFIX>] topic for each registered suffix.

Returns 30 acceleration values with 8 bit resolution. The data rate can be configured with request/accelerometer_v2_bricklet/<UID>/set_configuration and this callback can be enabled with request/accelerometer_v2_bricklet/<UID>/set_continuous_acceleration_configuration.

The unit of the values is g*256/10000.

The data is formated in the sequence "x, y, z, x, y, z, ..." depending on the enabled axis. Examples:

  • x, y, z enabled: "x, y, z, ... 20x ..., x, y, z"
  • x, z enabled: "x, z, ... 30x ..., x, z"
  • y enabled: "y, ... 60x ..., y"