Author | Rob Hamerling, Copyright (c) 2008..2009, all rights reserved. |
Adapted-by | Eur van Andel, Joep Suijs (refactoring) |
Compiler | >=2.4g |
Nibble interface for HD44780 compatible alphanumeric LCD screens. . Expects: - 2 pins for handshake: 'lcd_rs' and 'lcd_en' and - 1 port nibble for data: 'lcd_dataport' or - 4 lines for data: 'lcd_d4' .. 'lcd_d7' note: a 'port nibble' - the lower or higher 4 bits of a port - give faster and more compact code then random selected data lines. . Directions for use of this library in application programs (in this sequence): 1. Declare the following constants: const byte LCD_ROWS = 2 -- 1, 2 or 4 lines const byte LCD_CHARS = 16 -- 8, 16 or 20 chars per line and variables (aliases): var bit lcd_en is pin_A4 -- trigger var bit lcd_rs is pin_A5 -- cmd/data select and variables (aliases): var byte lcd_dataport is portA_low -- 4 data pins or var bit lcd_d4 is pin_A3 -- databit d4 pin var bit lcd_d5 is pin_A1 -- databit d5 pin var bit lcd_d6 is pin_C0 -- databit d6 pin var bit lcd_d7 is pin_C2 -- databit d7 pin . 2. Set the chosen LCD dataport and handshake pins to output: pin_A4_direction = output pin_A5_direction = output and portA_low_direction = all_output or pin_A3_direction = output -- set data pin as output pin_A1_direction = output -- set data pin as output pin_C0_direction = output -- set data pin as output pin_C2_direction = output -- set data pin as output . 3. Include this library. . 4. Call lcd_init() to initialize the lcd controller. . Above is an example for a 2x16 LCD. . See hd_44780_common for the LCD API.
_lcd_write_data(byte in value)
__lcd_write( byte in value )
__lcd_write_nibble( byte in value )
_lcd_write_command(byte in value)
lcd_init()
Initialize LCD controller to 4-bit mode
_lcd_write_data(byte in value)
Sends data byte into LCD
__lcd_write( byte in value )
Sends byte into LCD (this procedure is only used inside this library)
__lcd_write_nibble( byte in value )
Sends low nibble into LCD Can be used for both commands and data (requires no wait cycli inbetween upper and lower nibble) (this routine is only used inside this file)
_lcd_write_command(byte in value)
Sends command byte into LCD For slow commands an extra delay should be added