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Description
Generic I2C LCD Driver unit
Generic 16x2 or 20x4 LCD displays with an I2C interface are available from many suppliers and commonly include a Hitachi HD44780 LCD and NXP PCF8574 I/O expander to convert the I2C data into GPIO inputs for the display.
This unit combines the drivers for the HD44780 and PCF8574 to create a console device which can be used with the standard console and console window API.
Only text mode is supported as the HD44780 does not support setting individual pixels.
Some examples of generic displays that will work with the unit include the following:
https://www.amazon.com/SunFounder-Serial-Module-Display-Arduino/dp/B019K5X53O
https://www.auselectronicsdirect.com.au/2-x-16-lcd-display-module-with-i2c-interface-for-a
But you can find these units from many suppliers worldwide.
Constants
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I2CLCD specific constants I2CLCD_*
I2CLCD_CONSOLE_DESCRIPTION = 'Generic I2C LCD';
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Description of I2CLCD device
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I2CLCD_SIGNATURE = $00CF8574;
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I2CLCD GPIO I2CLCD_PIN_*
I2CLCD_PIN_RS = GPIO_PIN_0;
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GPIO pin for the LCD RS line
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I2CLCD_PIN_RW = GPIO_PIN_1;
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GPIO pin for the LCD RW line
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I2CLCD_PIN_EN = GPIO_PIN_2;
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GPIO pin for the LCD EN line
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I2CLCD_PIN_BACKLIGHT = GPIO_PIN_3;
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GPIO pin for the LCD Backlight
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I2CLCD_PIN_D4 = GPIO_PIN_4;
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GPIO pin for the LCD D4 line
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I2CLCD_PIN_D5 = GPIO_PIN_5;
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GPIO pin for the LCD D5 line
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I2CLCD_PIN_D6 = GPIO_PIN_6;
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GPIO pin for the LCD D6 line
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I2CLCD_PIN_D7 = GPIO_PIN_7;
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GPIO pin for the LCD D7 line
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Type definitions
I2CLCD display
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PI2CLCDDisplay = ^TI2CLCDDisplay;
TI2CLCDDisplay = record
Signature:LongWord;
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Signature for entry validation
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Width:LongWord;
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Width in columns of this display
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Height:LongWord;
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Height in rows of this display
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I2C:PI2CDevice;
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I2C device for this display
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GPIO:PGPIODevice;
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GPIO (PCF8574) device for this display
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Console:PConsoleDevice;
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Console (HD44780) device for this display
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Public variables
I2CLCD specific variables
I2CLCD_AUTOSTART:LongBool = True;
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If True then auto start the I2CLCD device on boot
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I2CLCD_I2C_ADDRESS:Word = $27;
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I2CLCD_I2C_DEVICE:String = 'I2C0';
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I2CLCD_LCD_WIDTH:LongWord = 16;
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I2CLCD_LCD_HEIGHT:LongWord = 2;
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Function declarations
Initialization functions
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procedure I2CLCDInit;
Description: Initialize the I2CLCD unit and parameters
| Note
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Called only during system startup
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function I2CLCDStart(const Device:String; Address:Word; Width,Height:LongWord):THandle;
Description: Start the I2CLCD driver and register the GPIO and Console devices associated with the display
| Device
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The I2C device that the PCF8574 I/O Expander on the display is connected to
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| Address
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The I2C address of the PCF8574 I/O Expander on the display
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| Width
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The width in columns of the HD44780 LCD on the display
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| Height
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The height in rows of the HD44780 LCD on the display
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| Return
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The handle of the I2CLCD on success or INVALID_HANDLE_VALUE on failure
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| Note
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This function will be called during startup if the parameter I2CLCD_AUTOSTART is True.
Can be called multiple times to support more than one LCD display.
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function I2CLCDStop(Handle:THandle):Boolean;
Description: Stop the I2CLCD driver and deregister the GPIO and Console devices associated with the display
| Handle
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The handle of the I2CLCD or INVALID_HANDLE_VALUE for the default display
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| Return
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True if completed or False on failure
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I2CLCD functions
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function I2CLCDBacklightOn(Handle:THandle):Boolean;
Description: Turn on the backlight on the I2CLCD display
| Handle
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The handle of the I2CLCD or INVALID_HANDLE_VALUE for the default display
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| Return
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True if completed or False on failure
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function I2CLCDBacklightOff(Handle:THandle):Boolean;
Description: Turn off the backlight on the I2CLCD display
| Handle
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The handle of the I2CLCD or INVALID_HANDLE_VALUE for the default display
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| Return
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True if completed or False on failure
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