LCD 20x4 Bricklet¶

Features¶

• 20x4 character alphanumeric display

• Switchable blue backlight

• 4 push-buttons

Description¶

This LCD Bricklet is equipped with a 20x4 character alphanumeric display with blue backlight and four push-buttons. It can be controlled with Bricks. The API allows to write characters to the LCD, get the state of the buttons, switch the backlight on or off and configure events for the buttons.

You can use this Bricklet to display text, for example a name of a song that is played on your PC or measurements from other Bricklets.

Technical Specifications¶

* without screws

Resources¶

• LCD charset (Download)

• KS0066U datasheet (Download)

• MCP23017 datasheet (Download)

• Schematic (Download)

• Outline and drilling plan (Download)

• Source code and design files (Download)

• 3D model (View online | Download: STEP, FreeCAD)

Test your LCD 20x4 Bricklet¶

To test a LCD 20x4 Bricklet you need to have Brick Daemon and Brick Viewer installed. Brick Daemon acts as a proxy between the USB interface of the Bricks and the API bindings. Brick Viewer connects to Brick Daemon. It helps to figure out basic information about the connected Bricks and Bricklets and allows to test them.

Connect the LCD 20x4 Bricklet to a Brick with a Bricklet Cable (see picture below).

If you connect the Brick to the PC over USB, you should see a new tab named "LCD 20x4 Bricklet" in the Brick Viewer after a moment. Select this tab. If everything went as expected the Brick Viewer should look as depicted below.

Input a string into the text field. You can choose the line and the start position at which the text is displayed. Press "Send Text" to display it. Press "Backlight On" to turn the backlight on. Play around with the four on-board buttons and look how their values change.

After this test you can go on with writing your own application. See the Programming Interface section for the API of the LCD 20x4 Bricklet and examples in different programming languages.

Change LCD's contrast¶

To modify the contrast you have to turn the potentiometer on the Bricklet with a screwdriver. The potentiometer is attached next to the Bricklet connector.

Attach external Buttons¶

The LCD Bricklet can be equipped with a pin header on the right hand side. To attach a switch or a button you have to connect on pin with one input (BTN0 to BTN3) and the other with GND.

Font¶

The Bricklet has an embedded font (ASCII subset in green) that allows fast and easy text rendering (up to 20x4 characters):

Case¶

A laser-cut case for the LCD 20x4 Bricklet is available.

The assembly is easiest if you follow the following steps:

• Screw LCD to top plate with spacers (10mm) at the bottom and long screws from the top,

• screw Bricklet to LCD with spacers (12mm),

• build up side plates,

• add button extensions to side plate,

• plug side plates into top plate and

• screw bottom plate to bottom spacers.

Below you can see an exploded assembly drawing of the LCD 20x4 Bricklet case:

Hint: There is a protective film on both sides of the plates, you have to remove it before assembly.

Programming Interface¶

See Programming Interface for a detailed description.