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+/*
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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 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 General Public License for more details.
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+ *
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+ * You should have received a copy of the GNU 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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+
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+#include <stdio.h>
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+#include <stdlib.h>
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+#include <stdint.h>
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+#include <stdarg.h>
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+
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+#include "wiringPi.h"
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+#include "lcd.h"
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+
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+// Commands
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+
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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_ON_OFF 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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+
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+#define LCD_ENTRY_SH 0x01
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+#define LCD_ENTRY_ID 0x02
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+
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+#define LCD_ON_OFF_B 0x01
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+#define LCD_ON_OFF_C 0x02
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+#define LCD_ON_OFF_D 0x04
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+
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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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+
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+#define LCD_CDSHIFT_RL 0x04
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+
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+struct lcdDataStruct
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+{
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+ uint8_t bits, rows, cols ;
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+ uint8_t rsPin, strbPin ;
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+ uint8_t dataPins [8] ;
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+} ;
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+
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+struct lcdDataStruct *lcds [MAX_LCDS] ;
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+
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+
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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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+
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+static void strobe (struct lcdDataStruct *lcd)
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+{
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+ digitalWrite (lcd->strbPin, 1) ; delayMicroseconds (1) ;
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+ digitalWrite (lcd->strbPin, 0) ; delayMicroseconds (50) ;
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+}
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+
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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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+
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+static void sendDataCmd (struct lcdDataStruct *lcd, uint8_t data)
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+{
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+ uint8_t i, d4 ;
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+
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+ if (lcd->bits == 4)
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+ {
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+ d4 = (data >> 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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+
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+ d4 = data & 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], (data & 1)) ;
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+ data >>= 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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+
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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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+
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+static void putCommand (struct lcdDataStruct *lcd, uint8_t command)
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+{
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+ digitalWrite (lcd->rsPin, 0) ;
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+ sendDataCmd (lcd, command) ;
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+}
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+
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+static void put4Command (struct lcdDataStruct *lcd, uint8_t command)
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+{
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+ uint8_t i ;
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+
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+ digitalWrite (lcd->rsPin, 0) ;
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+
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+ for (i = 0 ; i < 4 ; ++i)
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+ {
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+ digitalWrite (lcd->dataPins [i], (command & 1)) ;
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+ command >>= 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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+/*
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+ *********************************************************************************
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+ * User Code below here
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+ *********************************************************************************
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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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+
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+void lcdHome (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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+}
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+
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+void lcdClear (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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+}
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+
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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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+ *********************************************************************************
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+ */
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+
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+
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+void lcdPosition (int fd, int x, int y)
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+{
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+ static uint8_t rowOff [4] = { 0x00, 0x40, 0x14, 0x54 } ;
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+ struct lcdDataStruct *lcd = lcds [fd] ;
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+
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+ putCommand (lcd, x + (LCD_DGRAM | rowOff [y])) ;
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+}
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+
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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
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+ *********************************************************************************
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+ */
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+
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+void lcdPutchar (int fd, uint8_t data)
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+{
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+ struct lcdDataStruct *lcd = lcds [fd] ;
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+
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+ digitalWrite (lcd->rsPin, 1) ;
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+ sendDataCmd (lcd, data) ;
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+}
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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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+
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+void lcdPuts (int fd, 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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+
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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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+
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+void lcdPrintf (int fd, char *message, ...)
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+{
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+ va_list argp ;
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+ char buffer [1024] ;
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+
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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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+
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+ lcdPuts (fd, buffer) ;
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+}
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+
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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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+
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+int lcdInit (int rows, int cols, int bits, int rs, int strb,
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+ int d0, int d1, int d2, int d3, int d4, int d5, int d6, int d7)
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+{
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+ static int initialised = 0 ;
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+
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+ uint8_t 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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+
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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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+
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+// Simple sanity checks
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+
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+ if (! ((bits == 4) || (bits == 8)))
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+ return -1 ;
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+
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+ if ((rows < 0) || (rows > 20))
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+ return -1 ;
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+
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+ if ((cols < 0) || (cols > 20))
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+ return -1 ;
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+
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+// Create a new LCD:
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+
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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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+
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+ if (lcdFd == -1)
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+ return -1 ;
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+
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+ lcd = malloc (sizeof (struct lcdDataStruct)) ;
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+ if (lcd == NULL)
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+ return -1 ;
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+
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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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+
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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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+
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+ lcds [lcdFd] = lcd ;
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+
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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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+
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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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+
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+
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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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+
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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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+
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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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+
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+// Rest of the initialisation sequence
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+
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+ putCommand (lcd, LCD_ON_OFF | LCD_ON_OFF_D) ; delay (2) ;
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+ putCommand (lcd, LCD_ENTRY | LCD_ENTRY_ID) ; delay (2) ;
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+ putCommand (lcd, LCD_CDSHIFT | LCD_CDSHIFT_RL) ; delay (2) ;
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+ putCommand (lcd, LCD_CLEAR) ; delay (5) ;
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+
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+ return lcdFd ;
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+}
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