CheapLCD Shield

A convenience library for using the SainSmart LCD Keypad Shield V1.0 and compatible shields.

This library extends the LiquidCrystal library, automatically handles pin setup for LCD, backlight, and buttons, and provides an interface to the backlight and buttons.

This library should be compatible with LCD Keypad shields from:

Manufacturer	Model	Tested
SainSmart	LCD Keypad Shield V1.0	✓
DFRobot	DFR0009 LCD Shield for Arduino
HiLetgo	LCD1602 I/O exp. LCD Keypad Shield for Arduino
RobotDyne	LCD keypad Shield, 1602 BLUE LCD display

Usage:

Call begin() or begin(bool backlightOnNow, uint8_t backlightLevel) in your sketch setup() function.

After that, use backlightOn() and backlightOff() to turn the backlight on and off, and backlightLevel() to adjust the brightness (0-255 value). readButton() may be used to detect button presses on this shield.

Otherwise, use this exactly the same as the standard LiquidCrystal class.

Functions

Note: Always call begin(); or begin(backlightOnNow, backlightLevel); before using this library!

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begin();

Initialize LCD Keypad Shield with backlight on full.

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begin(backlightOnNow, backlightLevel);

Initialize LCD Keypad Shield. User specifies whether to turn the backlight on immediately with backlightOnNow (true or false) and the backlight brightness level setting (0-255).

If backlightOnNow parameter is specified as false, use backlightOn(); later to turn it on when desired.

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backlightOn();

Turns the backlight on.

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backlightOff();

Turns the backlight off.

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backlightLevel(level);

Sets backlight to a specified brightness value, where level is a whole number from 0-255. Can be used at any time after begin() or begin(..). Only sets backlight brightness, and will not turn the backlight on or off.

Note: If the backlight is on and backlightLevel(0); is called, the display will go dark and can be restored by calling backlightLevel(x); where x is greater than zero. Calling backlightLevel(0); is not recommended due to the confusion it may cause (unless you have a good reason).

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CLCD_Button_t button = readButton();

Reads button array and returns which button was pressed (or none)

Warning: The hardware cannot tell when multiple buttons are pressed due to the way the buttons are multiplexed on a single analog pin!

Returns an enum indicating which button is being pressed (or none)

Returns one of:

• BTN_RIGHT
• BTN_UP
• BTN_DOWN
• BTN_LEFT
• BTN_SELECT
• BTN_NONE

Other Documentation

LCD Keypad pin assignments:

Arduino Pin	LCD Keypad Shield Usage
A0	Multiplexed button pin
D4	LCD DB4
D5	LCD DB5
D6	LCD DB6
D7	LCD DB7
D8	LCD RS
D9	LCD E (Enable)
D10	Backlight Control

The schematic is located in the extras directory and is duplicated as a convenience. I do not own it.