Modbus - LCD 16x2 Bricklet

This is the description of the Modbus protocol for the LCD 16x2 Bricklet. General information and technical specifications for the LCD 16x2 Bricklet are summarized in its hardware description.

API

A general description of the Modbus protocol structure can be found here.

Basic Functions

BrickletLCD16x2.write_line
Function ID:

1

Request:
  • line -- uint8
  • position -- uint8
  • text -- char[16]
Response:

no response

Writes text to a specific line (0 to 1) with a specific position (0 to 15). The text can have a maximum of 16 characters.

For example: (0, 5, "Hello") will write Hello in the middle of the first line of the display.

The display uses a special charset that includes all ASCII characters except backslash and tilde. The LCD charset also includes several other non-ASCII characters, see the charset specification for details. The Unicode example above shows how to specify non-ASCII characters and how to translate from Unicode to the LCD charset.

BrickletLCD16x2.clear_display
Function ID:2
Request:empty payload
Response:no response

Deletes all characters from the display.

BrickletLCD16x2.backlight_on
Function ID:3
Request:empty payload
Response:no response

Turns the backlight on.

BrickletLCD16x2.backlight_off
Function ID:4
Request:empty payload
Response:no response

Turns the backlight off.

BrickletLCD16x2.is_backlight_on
Function ID:

5

Request:

empty payload

Response:
  • backlight -- bool

Returns true if the backlight is on and false otherwise.

Advanced Functions

BrickletLCD16x2.set_config
Function ID:

6

Request:
  • cursor -- bool
  • blinking -- bool
Response:

no response

Configures if the cursor (shown as "_") should be visible and if it should be blinking (shown as a blinking block). The cursor position is one character behind the the last text written with write_line.

The default is (false, false).

BrickletLCD16x2.get_config
Function ID:

7

Request:

empty payload

Response:
  • cursor -- bool
  • blinking -- bool

Returns the configuration as set by set_config.

BrickletLCD16x2.is_button_pressed
Function ID:

8

Request:
  • button -- uint8
Response:
  • pressed -- bool

Returns true if the button (0 to 2) is pressed.

If you want to react on button presses and releases it is recommended to use the CALLBACK_BUTTON_PRESSED and CALLBACK_BUTTON_RELEASED callbacks.

BrickletLCD16x2.set_custom_character
Function ID:

11

Request:
  • index -- uint8
  • character -- uint8[8]
Response:

no response

The LCD 16x2 Bricklet can store up to 8 custom characters. The characters consist of 5x8 pixels and can be addressed with the index 0-7. To describe the pixels, the first 5 bits of 8 bytes are used. For example, to make a custom character "H", you should transfer the following:

  • character[0] = 0b00010001 (decimal value 17)
  • character[1] = 0b00010001 (decimal value 17)
  • character[2] = 0b00010001 (decimal value 17)
  • character[3] = 0b00011111 (decimal value 31)
  • character[4] = 0b00010001 (decimal value 17)
  • character[5] = 0b00010001 (decimal value 17)
  • character[6] = 0b00010001 (decimal value 17)
  • character[7] = 0b00000000 (decimal value 0)

The characters can later be written with write_line by using the characters with the byte representation 8 to 15.

You can play around with the custom characters in Brick Viewer since version 2.0.1.

Custom characters are stored by the LCD in RAM, so they have to be set after each startup.

New in version 2.0.1 (Plugin).

BrickletLCD16x2.get_custom_character
Function ID:

12

Request:
  • index -- uint8
Response:
  • character -- uint8[8]

Returns the custom character for a given index, as set with set_custom_character.

New in version 2.0.1 (Plugin).

BrickletLCD16x2.get_identity
Function ID:

255

Request:

empty payload

Response:
  • uid -- char[8]
  • connected_uid -- char[8]
  • position -- char
  • hardware_version -- uint8[3]
  • firmware_version -- uint8[3]
  • device_identifier -- uint16

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

Callbacks

BrickletLCD16x2.CALLBACK_BUTTON_PRESSED
Function ID:

9

Response:
  • button -- uint8

This callback is triggered when a button is pressed. The response value is the number of the button (0 to 2).

BrickletLCD16x2.CALLBACK_BUTTON_RELEASED
Function ID:

10

Response:
  • button -- uint8

This callback is triggered when a button is released. The response value is the number of the button (0 to 2).