MQTT - OLED 128x64 Bricklet 2.0

This is the description of the MQTT API bindings for the OLED 128x64 Bricklet 2.0. General information and technical specifications for the OLED 128x64 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).

Hello World

Download (example-hello-world.txt)

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# Change XYZ to the UID of your OLED 128x64 Bricklet 2.0

setup:
    # Clear display
    publish '' to tinkerforge/request/oled_128x64_v2_bricklet/XYZ/clear_display 
    
    # Write "Hello World" starting from upper left corner of the screen
    publish '{"line": 0, "position": 0, "text": "Hello World"}' to tinkerforge/request/oled_128x64_v2_bricklet/XYZ/write_line 

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/oled_128x64_v2_bricklet/<UID>/write_pixels
Request:
  • x_start – Type: int, Range: [0 to 255]
  • y_start – Type: int, Range: [0 to 255]
  • x_end – Type: int, Range: [0 to 255]
  • y_end – Type: int, Range: [0 to 255]
  • pixels – Type: [bool, ...], Length: variable
Response:
  • no response

Writes pixels to the specified window.

The x-axis goes from 0 to 127 and the y-axis from 0 to 63. The pixels are written into the window line by line top to bottom and each line is written from left to right.

If automatic draw is enabled (default) the pixels are directly written to the screen. Only pixels that have actually changed are updated on the screen, the rest stays the same.

If automatic draw is disabled the pixels are written to an internal buffer and the buffer is transferred to the display only after request/oled_128x64_v2_bricklet/<UID>/draw_buffered_frame is called. This can be used to avoid flicker when drawing a complex frame in multiple steps.

Automatic draw can be configured with the request/oled_128x64_v2_bricklet/<UID>/set_display_configuration function.

request/oled_128x64_v2_bricklet/<UID>/read_pixels
Request:
  • x_start – Type: int, Range: [0 to 255]
  • y_start – Type: int, Range: [0 to 255]
  • x_end – Type: int, Range: [0 to 255]
  • y_end – Type: int, Range: [0 to 255]
Response:
  • pixels – Type: [bool, ...], Length: variable

Reads pixels from the specified window.

The x-axis goes from 0 to 127 and the y-axis from 0 to 63. The pixels are read from the window line by line top to bottom and each line is read from left to right.

If automatic draw is enabled (default) the pixels that are read are always the same that are shown on the display.

If automatic draw is disabled the pixels are read from the internal buffer (see request/oled_128x64_v2_bricklet/<UID>/draw_buffered_frame).

Automatic draw can be configured with the request/oled_128x64_v2_bricklet/<UID>/set_display_configuration function.

request/oled_128x64_v2_bricklet/<UID>/clear_display
Request:
  • empty payload
Response:
  • no response

Clears the complete content of the display.

If automatic draw is enabled (default) the pixels are directly cleared.

If automatic draw is disabled the the internal buffer is cleared and the buffer is transferred to the display only after request/oled_128x64_v2_bricklet/<UID>/draw_buffered_frame is called. This can be used to avoid flicker when drawing a complex frame in multiple steps.

Automatic draw can be configured with the request/oled_128x64_v2_bricklet/<UID>/set_display_configuration function.

request/oled_128x64_v2_bricklet/<UID>/write_line
Request:
  • line – Type: int, Range: [0 to 255]
  • position – Type: int, Range: [0 to 255]
  • text – Type: string, Length: up to 22
Response:
  • no response

Writes text to a specific line (0 to 7) with a specific position (0 to 21). The text can have a maximum of 22 characters.

For example: (1, 10, "Hello") will write Hello in the middle of the second line of the display.

The display uses a special 5x7 pixel charset. You can view the characters of the charset in Brick Viewer.

If automatic draw is enabled (default) the text is directly written to the screen. Only pixels that have actually changed are updated on the screen, the rest stays the same.

If automatic draw is disabled the text is written to an internal buffer and the buffer is transferred to the display only after request/oled_128x64_v2_bricklet/<UID>/draw_buffered_frame is called. This can be used to avoid flicker when drawing a complex frame in multiple steps.

Automatic draw can be configured with the request/oled_128x64_v2_bricklet/<UID>/set_display_configuration function.

request/oled_128x64_v2_bricklet/<UID>/draw_buffered_frame
Request:
  • force_complete_redraw – Type: bool
Response:
  • no response

Draws the currently buffered frame. Normally each call of request/oled_128x64_v2_bricklet/<UID>/write_pixels and request/oled_128x64_v2_bricklet/<UID>/write_line draws directly onto the display. If you turn automatic draw off (request/oled_128x64_v2_bricklet/<UID>/set_display_configuration), the data is written in an internal buffer and only transferred to the display by calling this function. This can be used to avoid flicker when drawing a complex frame in multiple steps.

Set the force complete redraw to true to redraw the whole display instead of only the changed parts. Normally it should not be necessary to set this to true. It may only become necessary in case of stuck pixels because of errors.

Advanced Functions

request/oled_128x64_v2_bricklet/<UID>/set_display_configuration
Request:
  • contrast – Type: int, Range: [0 to 255]
  • invert – Type: bool
  • automatic_draw – Type: bool
Response:
  • no response

Sets the configuration of the display.

You can set a contrast value from 0 to 255 and you can invert the color (white/black) of the display.

If automatic draw is set to true, the display is automatically updated with every call of request/oled_128x64_v2_bricklet/<UID>/write_pixels or request/oled_128x64_v2_bricklet/<UID>/write_line. If it is set to false, the changes are written into an internal buffer and only shown on the display after a call of request/oled_128x64_v2_bricklet/<UID>/draw_buffered_frame.

The default values are contrast 143, inverting off and automatic draw on.

request/oled_128x64_v2_bricklet/<UID>/get_display_configuration
Request:
  • empty payload
Response:
  • contrast – Type: int, Range: [0 to 255]
  • invert – Type: bool
  • automatic_draw – Type: bool

Returns the configuration as set by request/oled_128x64_v2_bricklet/<UID>/set_display_configuration.

request/oled_128x64_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/oled_128x64_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/oled_128x64_v2_bricklet/<UID>/get_bootloader_mode
Request:
  • empty payload
Response:
  • mode – Type: int, Range: See symbols

Returns the current bootloader mode, see request/oled_128x64_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/oled_128x64_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/oled_128x64_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/oled_128x64_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/oled_128x64_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/oled_128x64_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/oled_128x64_v2_bricklet/<UID>/get_status_led_config
Request:
  • empty payload
Response:
  • config – Type: int, Range: See symbols

Returns the configuration as set by request/oled_128x64_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/oled_128x64_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/oled_128x64_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/oled_128x64_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/oled_128x64_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/oled_128x64_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 OLED 128x64 2.0's name in a human readable form.