From 4f93c76c211526d1a20f32aef7ca0f70ba9d8b34 Mon Sep 17 00:00:00 2001
From: Beatrice Pscheidl <beatrice.pscheidl@gmail.com>
Date: Fri, 9 Apr 2021 18:57:40 +0200
Subject: [PATCH] Create i2clcd.c

---
 i2clcd.c | 199 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 199 insertions(+)
 create mode 100644 i2clcd.c

diff --git a/i2clcd.c b/i2clcd.c
new file mode 100644
index 0000000..34c30bd
--- /dev/null
+++ b/i2clcd.c
@@ -0,0 +1,199 @@
+
+/*
+*
+* by Lewis Loflin www.bristolwatch.com lewis@bvu.net
+* http://www.bristolwatch.com/rpi/i2clcd.htm
+* Using wiringPi by Gordon Henderson
+*
+*
+* Port over lcd_i2c.py to C and added improvements.
+* Supports 16x2 and 20x4 screens.
+* This was to learn now the I2C lcd displays operate.
+* There is no warrenty of any kind use at your own risk.
+*
+*/
+
+/*
+*
+* adaptions by B. Pscheidl for 20x4 LCD
+* and pigpio http://abyz.me.uk/rpi/pigpio/
+*
+*/
+
+#include <pigpio.h> // -lpigpio -lrt
+#include <stdlib.h>
+#include <stdio.h>
+
+// Define some device parameters
+#define I2C_ADDR   0x27 // I2C device address
+
+// Define some device constants
+#define LCD_CHR  1 // Mode - Sending data
+#define LCD_CMD  0 // Mode - Sending command
+
+#define LINE1  0x80 // 1st line
+#define LINE2  0xC0 // 2nd line
+#define LINE3  0x94 // 3rd line
+#define LINE4  0xD4 // 4th line
+
+#define LCD_BACKLIGHT   0x08  // On
+// LCD_BACKLIGHT = 0x00  # Off
+
+#define ENABLE  0b00000100 // Enable bit
+
+void lcd_init(void);
+void lcd_byte(int bits, int mode);
+void lcd_toggle_enable(int bits);
+
+// added by Lewis
+void typeInt(int i);
+void typeFloat(float myFloat);
+void lcdLoc(int line); //move cursor
+void ClrLcd(void); // clr LCD return home
+void typeln(const char *s);
+void typeChar(char val);
+int fd;  // seen by all subroutines
+
+//Test program
+int main_()   {
+  if (gpioInitialise() < 0)
+    exit (1);
+
+  fd = i2cOpen(1, I2C_ADDR, 0);
+
+  lcd_init(); // setup LCD
+
+  char array1[] = "Hello world!";
+
+  while (1)   {
+    lcdLoc(LINE1);
+    typeln("Using wiringPi");
+    lcdLoc(LINE2);
+    typeln("Geany editor.");
+
+    gpioDelay(2000000);
+    ClrLcd();
+    lcdLoc(LINE1);
+    typeln("I2c  Programmed");
+    lcdLoc(LINE2);
+    typeln("in C not Python.");
+
+    gpioDelay(2000000);
+    ClrLcd();
+    lcdLoc(LINE1);
+    typeln("Arduino like");
+    lcdLoc(LINE2);
+    typeln("fast and easy.");
+
+    gpioDelay(2000000);
+    ClrLcd();
+    lcdLoc(LINE1);
+    typeln(array1);
+
+    //4 lines test
+    gpioDelay(2000000);
+    ClrLcd();
+    lcdLoc(LINE1);
+    typeln(array1);
+    lcdLoc(LINE2);
+    typeln("Line 2 on 20x4");
+    lcdLoc(LINE3);
+    typeln("Added a 3rd line!");
+    lcdLoc(LINE4);
+    typeln("And a 4th for fun...");
+
+
+    gpioDelay(2000000);
+    ClrLcd(); // defaults LINE1
+    typeln("Int  ");
+    int value = 20125;
+    typeInt(value);
+
+    gpioDelay(2000000);
+    lcdLoc(LINE2);
+    typeln("Float ");
+    float FloatVal = 10045.25989;
+    typeFloat(FloatVal);
+    gpioDelay(4000000);
+  }
+
+  return 0;
+}
+
+
+// float to string
+void typeFloat(float myFloat)   {
+  char buffer[20];
+  sprintf(buffer, "%4.2f",  myFloat);
+  typeln(buffer);
+}
+
+// int to string
+void typeInt(int i)   {
+  char array1[20];
+  sprintf(array1, "%d",  i);
+  typeln(array1);
+}
+
+// clr lcd go home loc 0x80
+void ClrLcd(void)   {
+  lcd_byte(0x01, LCD_CMD);
+  lcd_byte(0x02, LCD_CMD);
+}
+
+// go to location on LCD
+void lcdLoc(int line)   {
+  lcd_byte(line, LCD_CMD);
+}
+
+// out char to LCD at current position
+void typeChar(char val)   {
+  lcd_byte(val, LCD_CHR);
+}
+
+
+// this allows use of any size string
+void typeln(const char *s)   {
+  while ( *s ) lcd_byte(*(s++), LCD_CHR);
+}
+
+void lcd_byte(int bits, int mode)   {
+
+  //Send byte to data pins
+  // bits = the data
+  // mode = 1 for data, 0 for command
+  int bits_high;
+  int bits_low;
+  // uses the two half byte writes to LCD
+  bits_high = mode | (bits & 0xF0) | LCD_BACKLIGHT ;
+  bits_low = mode | ((bits << 4) & 0xF0) | LCD_BACKLIGHT ;
+
+  // High bits
+  i2cReadByteData(fd, bits_high);
+  lcd_toggle_enable(bits_high);
+
+  // Low bits
+  i2cReadByteData(fd, bits_low);
+  lcd_toggle_enable(bits_low);
+}
+
+void lcd_toggle_enable(int bits)   {
+  // Toggle enable pin on LCD display
+  gpioDelay(500);
+  i2cReadByteData(fd, (bits | ENABLE));
+  gpioDelay(500);
+  i2cReadByteData(fd, (bits & ~ENABLE));
+  gpioDelay(500);
+}
+
+
+void lcd_init()   {
+  // Initialise display
+  lcd_byte(0x33, LCD_CMD); // Initialise
+  lcd_byte(0x32, LCD_CMD); // Initialise
+  lcd_byte(0x06, LCD_CMD); // Cursor move direction
+  lcd_byte(0x0C, LCD_CMD); // 0x0F On, Blink Off
+  lcd_byte(0x28, LCD_CMD); // Data length, number of lines, font size
+  lcd_byte(0x01, LCD_CMD); // Clear display
+  gpioDelay(500);
+}