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495 lines
11 KiB
495 lines
11 KiB
/* |
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* lcd.c: |
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* Text-based LCD driver. |
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* This is designed to drive the parallel interface LCD drivers |
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* based in the Hitachi HD44780U controller and compatables. |
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* |
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* Copyright (c) 2012 Gordon Henderson. |
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*********************************************************************** |
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* This file is part of wiringPi: |
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* https://projects.drogon.net/raspberry-pi/wiringpi/ |
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* |
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* wiringPi is free software: you can redistribute it and/or modify |
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* it under the terms of the GNU Lesser General Public License as published by |
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* the Free Software Foundation, either version 3 of the License, or |
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* (at your option) any later version. |
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* |
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* wiringPi is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public License |
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* along with wiringPi. If not, see <http://www.gnu.org/licenses/>. |
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*********************************************************************** |
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*/ |
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#include <stdio.h> |
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#include <stdlib.h> |
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#include <stdarg.h> |
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#include <wiringPi.h> |
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#include "lcd.h" |
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#ifndef TRUE |
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# define TRUE (1==1) |
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# define FALSE (1==2) |
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#endif |
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// HD44780U Commands |
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#define LCD_CLEAR 0x01 |
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#define LCD_HOME 0x02 |
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#define LCD_ENTRY 0x04 |
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#define LCD_CTRL 0x08 |
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#define LCD_CDSHIFT 0x10 |
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#define LCD_FUNC 0x20 |
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#define LCD_CGRAM 0x40 |
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#define LCD_DGRAM 0x80 |
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// Bits in the entry register |
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#define LCD_ENTRY_SH 0x01 |
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#define LCD_ENTRY_ID 0x02 |
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// Bits in the control register |
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#define LCD_BLINK_CTRL 0x01 |
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#define LCD_CURSOR_CTRL 0x02 |
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#define LCD_DISPLAY_CTRL 0x04 |
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// Bits in the function register |
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#define LCD_FUNC_F 0x04 |
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#define LCD_FUNC_N 0x08 |
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#define LCD_FUNC_DL 0x10 |
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#define LCD_CDSHIFT_RL 0x04 |
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struct lcdDataStruct |
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{ |
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int bits, rows, cols ; |
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int rsPin, strbPin ; |
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int dataPins [8] ; |
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int cx, cy ; |
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} ; |
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struct lcdDataStruct *lcds [MAX_LCDS] ; |
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static int lcdControl ; |
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// Row offsets |
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static const int rowOff [4] = { 0x00, 0x40, 0x14, 0x54 } ; |
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/* |
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* strobe: |
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* Toggle the strobe (Really the "E") pin to the device. |
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* According to the docs, data is latched on the falling edge. |
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********************************************************************************* |
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*/ |
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static void strobe (const struct lcdDataStruct *lcd) |
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{ |
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// Note timing changes for new version of delayMicroseconds () |
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digitalWrite (lcd->strbPin, 1) ; delayMicroseconds (50) ; |
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digitalWrite (lcd->strbPin, 0) ; delayMicroseconds (50) ; |
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} |
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/* |
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* sentDataCmd: |
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* Send an data or command byte to the display. |
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********************************************************************************* |
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*/ |
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static void sendDataCmd (const struct lcdDataStruct *lcd, unsigned char data) |
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{ |
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register unsigned char myData = data ; |
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unsigned char i, d4 ; |
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if (lcd->bits == 4) |
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{ |
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d4 = (myData >> 4) & 0x0F; |
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for (i = 0 ; i < 4 ; ++i) |
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{ |
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digitalWrite (lcd->dataPins [i], (d4 & 1)) ; |
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d4 >>= 1 ; |
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} |
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strobe (lcd) ; |
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d4 = myData & 0x0F ; |
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for (i = 0 ; i < 4 ; ++i) |
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{ |
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digitalWrite (lcd->dataPins [i], (d4 & 1)) ; |
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d4 >>= 1 ; |
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} |
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} |
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else |
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{ |
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for (i = 0 ; i < 8 ; ++i) |
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{ |
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digitalWrite (lcd->dataPins [i], (myData & 1)) ; |
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myData >>= 1 ; |
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} |
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} |
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strobe (lcd) ; |
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} |
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/* |
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* putCommand: |
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* Send a command byte to the display |
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********************************************************************************* |
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*/ |
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static void putCommand (const struct lcdDataStruct *lcd, unsigned char command) |
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{ |
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digitalWrite (lcd->rsPin, 0) ; |
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sendDataCmd (lcd, command) ; |
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delay (2) ; |
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} |
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static void put4Command (const struct lcdDataStruct *lcd, unsigned char command) |
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{ |
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register unsigned char myCommand = command ; |
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register unsigned char i ; |
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digitalWrite (lcd->rsPin, 0) ; |
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for (i = 0 ; i < 4 ; ++i) |
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{ |
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digitalWrite (lcd->dataPins [i], (myCommand & 1)) ; |
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myCommand >>= 1 ; |
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} |
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strobe (lcd) ; |
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} |
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/* |
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********************************************************************************* |
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* User Callable code below here |
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********************************************************************************* |
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*/ |
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/* |
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* lcdHome: lcdClear: |
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* Home the cursor or clear the screen. |
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********************************************************************************* |
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*/ |
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void lcdHome (const int fd) |
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{ |
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struct lcdDataStruct *lcd = lcds [fd] ; |
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putCommand (lcd, LCD_HOME) ; |
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lcd->cx = lcd->cy = 0 ; |
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delay (5) ; |
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} |
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void lcdClear (const int fd) |
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{ |
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struct lcdDataStruct *lcd = lcds [fd] ; |
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putCommand (lcd, LCD_CLEAR) ; |
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putCommand (lcd, LCD_HOME) ; |
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lcd->cx = lcd->cy = 0 ; |
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delay (5) ; |
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} |
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/* |
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* lcdDisplay: lcdCursor: lcdCursorBlink: |
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* Turn the display, cursor, cursor blinking on/off |
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********************************************************************************* |
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*/ |
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void lcdDisplay (const int fd, int state) |
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{ |
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struct lcdDataStruct *lcd = lcds [fd] ; |
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if (state) |
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lcdControl |= LCD_DISPLAY_CTRL ; |
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else |
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lcdControl &= ~LCD_DISPLAY_CTRL ; |
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putCommand (lcd, LCD_CTRL | lcdControl) ; |
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} |
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void lcdCursor (const int fd, int state) |
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{ |
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struct lcdDataStruct *lcd = lcds [fd] ; |
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if (state) |
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lcdControl |= LCD_CURSOR_CTRL ; |
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else |
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lcdControl &= ~LCD_CURSOR_CTRL ; |
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putCommand (lcd, LCD_CTRL | lcdControl) ; |
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} |
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void lcdCursorBlink (const int fd, int state) |
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{ |
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struct lcdDataStruct *lcd = lcds [fd] ; |
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if (state) |
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lcdControl |= LCD_BLINK_CTRL ; |
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else |
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lcdControl &= ~LCD_BLINK_CTRL ; |
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putCommand (lcd, LCD_CTRL | lcdControl) ; |
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} |
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/* |
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* lcdSendCommand: |
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* Send any arbitary command to the display |
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********************************************************************************* |
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*/ |
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void lcdSendCommand (const int fd, unsigned char command) |
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{ |
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struct lcdDataStruct *lcd = lcds [fd] ; |
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putCommand (lcd, command) ; |
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} |
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/* |
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* lcdPosition: |
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* Update the position of the cursor on the display. |
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* Ignore invalid locations. |
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********************************************************************************* |
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*/ |
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void lcdPosition (const int fd, int x, int y) |
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{ |
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struct lcdDataStruct *lcd = lcds [fd] ; |
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if ((x > lcd->cols) || (x < 0)) |
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return ; |
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if ((y > lcd->rows) || (y < 0)) |
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return ; |
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putCommand (lcd, x + (LCD_DGRAM | rowOff [y])) ; |
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lcd->cx = x ; |
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lcd->cy = y ; |
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} |
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/* |
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* lcdCharDef: |
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* Defines a new character in the CGRAM |
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********************************************************************************* |
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*/ |
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void lcdCharDef (const int fd, int index, unsigned char data [8]) |
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{ |
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struct lcdDataStruct *lcd = lcds [fd] ; |
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int i ; |
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putCommand (lcd, LCD_CGRAM | ((index & 7) << 3)) ; |
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digitalWrite (lcd->rsPin, 1) ; |
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for (i = 0 ; i < 8 ; ++i) |
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sendDataCmd (lcd, data [i]) ; |
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} |
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/* |
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* lcdPutchar: |
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* Send a data byte to be displayed on the display. We implement a very |
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* simple terminal here - with line wrapping, but no scrolling. Yet. |
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********************************************************************************* |
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*/ |
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void lcdPutchar (const int fd, unsigned char data) |
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{ |
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struct lcdDataStruct *lcd = lcds [fd] ; |
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digitalWrite (lcd->rsPin, 1) ; |
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sendDataCmd (lcd, data) ; |
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if (++lcd->cx == lcd->cols) |
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{ |
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lcd->cx = 0 ; |
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if (++lcd->cy == lcd->rows) |
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lcd->cy = 0 ; |
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putCommand (lcd, lcd->cx + (LCD_DGRAM | rowOff [lcd->cy])) ; |
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} |
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} |
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/* |
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* lcdPuts: |
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* Send a string to be displayed on the display |
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********************************************************************************* |
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*/ |
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void lcdPuts (const int fd, const char *string) |
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{ |
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while (*string) |
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lcdPutchar (fd, *string++) ; |
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} |
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/* |
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* lcdPrintf: |
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* Printf to an LCD display |
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********************************************************************************* |
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*/ |
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void lcdPrintf (const int fd, const char *message, ...) |
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{ |
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va_list argp ; |
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char buffer [1024] ; |
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va_start (argp, message) ; |
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vsnprintf (buffer, 1023, message, argp) ; |
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va_end (argp) ; |
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lcdPuts (fd, buffer) ; |
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} |
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/* |
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* lcdInit: |
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* Take a lot of parameters and initialise the LCD, and return a handle to |
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* that LCD, or -1 if any error. |
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********************************************************************************* |
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*/ |
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int lcdInit (const int rows, const int cols, const int bits, |
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const int rs, const int strb, |
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const int d0, const int d1, const int d2, const int d3, const int d4, |
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const int d5, const int d6, const int d7) |
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{ |
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static int initialised = 0 ; |
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unsigned char func ; |
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int i ; |
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int lcdFd = -1 ; |
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struct lcdDataStruct *lcd ; |
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if (initialised == 0) |
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{ |
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initialised = 1 ; |
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for (i = 0 ; i < MAX_LCDS ; ++i) |
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lcds [i] = NULL ; |
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} |
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// Simple sanity checks |
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if (! ((bits == 4) || (bits == 8))) |
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return -1 ; |
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if ((rows < 0) || (rows > 20)) |
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return -1 ; |
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if ((cols < 0) || (cols > 20)) |
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return -1 ; |
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// Create a new LCD: |
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for (i = 0 ; i < MAX_LCDS ; ++i) |
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{ |
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if (lcds [i] == NULL) |
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{ |
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lcdFd = i ; |
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break ; |
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} |
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} |
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if (lcdFd == -1) |
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return -1 ; |
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lcd = (struct lcdDataStruct *)malloc (sizeof (struct lcdDataStruct)) ; |
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if (lcd == NULL) |
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return -1 ; |
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lcd->rsPin = rs ; |
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lcd->strbPin = strb ; |
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lcd->bits = 8 ; // For now - we'll set it properly later. |
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lcd->rows = rows ; |
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lcd->cols = cols ; |
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lcd->cx = 0 ; |
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lcd->cy = 0 ; |
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lcd->dataPins [0] = d0 ; |
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lcd->dataPins [1] = d1 ; |
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lcd->dataPins [2] = d2 ; |
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lcd->dataPins [3] = d3 ; |
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lcd->dataPins [4] = d4 ; |
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lcd->dataPins [5] = d5 ; |
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lcd->dataPins [6] = d6 ; |
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lcd->dataPins [7] = d7 ; |
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lcds [lcdFd] = lcd ; |
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digitalWrite (lcd->rsPin, 0) ; pinMode (lcd->rsPin, OUTPUT) ; |
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digitalWrite (lcd->strbPin, 0) ; pinMode (lcd->strbPin, OUTPUT) ; |
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for (i = 0 ; i < bits ; ++i) |
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{ |
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digitalWrite (lcd->dataPins [i], 0) ; |
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pinMode (lcd->dataPins [i], OUTPUT) ; |
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} |
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delay (35) ; // mS |
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// 4-bit mode? |
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// OK. This is a PIG and it's not at all obvious from the documentation I had, |
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// so I guess some others have worked through either with better documentation |
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// or more trial and error... Anyway here goes: |
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// |
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// It seems that the controller needs to see the FUNC command at least 3 times |
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// consecutively - in 8-bit mode. If you're only using 8-bit mode, then it appears |
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// that you can get away with one func-set, however I'd not rely on it... |
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// |
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// So to set 4-bit mode, you need to send the commands one nibble at a time, |
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// the same three times, but send the command to set it into 8-bit mode those |
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// three times, then send a final 4th command to set it into 4-bit mode, and only |
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// then can you flip the switch for the rest of the library to work in 4-bit |
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// mode which sends the commands as 2 x 4-bit values. |
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if (bits == 4) |
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{ |
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func = LCD_FUNC | LCD_FUNC_DL ; // Set 8-bit mode 3 times |
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put4Command (lcd, func >> 4) ; delay (35) ; |
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put4Command (lcd, func >> 4) ; delay (35) ; |
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put4Command (lcd, func >> 4) ; delay (35) ; |
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func = LCD_FUNC ; // 4th set: 4-bit mode |
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put4Command (lcd, func >> 4) ; delay (35) ; |
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lcd->bits = 4 ; |
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} |
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else |
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{ |
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func = LCD_FUNC | LCD_FUNC_DL ; |
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putCommand (lcd, func ) ; delay (35) ; |
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putCommand (lcd, func ) ; delay (35) ; |
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putCommand (lcd, func ) ; delay (35) ; |
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} |
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if (lcd->rows > 1) |
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{ |
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func |= LCD_FUNC_N ; |
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putCommand (lcd, func) ; delay (35) ; |
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} |
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// Rest of the initialisation sequence |
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lcdDisplay (lcdFd, TRUE) ; |
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lcdCursor (lcdFd, FALSE) ; |
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lcdCursorBlink (lcdFd, FALSE) ; |
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lcdClear (lcdFd) ; |
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putCommand (lcd, LCD_ENTRY | LCD_ENTRY_ID) ; |
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putCommand (lcd, LCD_CDSHIFT | LCD_CDSHIFT_RL) ; |
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return lcdFd ; |
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}
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