I2CLiquidCrystalを読み解く
確認の時に使用したライブラリの中を見てみる。
まずはヘッダ
・I2CLiquidCrystal.h
#ifndef I2CLiquidCrystal_h
#define I2CLiquidCrystal_h
#include <inttypes.h>
#include <Print.h>
// commands
#define LCD_CLEARDISPLAY 0x01
#define LCD_RETURNHOME 0x02
#define LCD_ENTRYMODESET 0x04
#define LCD_DISPLAYCONTROL 0x08
#define LCD_CURSORSHIFT 0x10
#define LCD_FUNCTIONSET 0x20
#define LCD_SETCGRAMADDR 0x40
#define LCD_SETDDRAMADDR 0x80
// flags for display entry mode
#define LCD_ENTRYRIGHT 0x00
#define LCD_ENTRYLEFT 0x02
#define LCD_ENTRYSHIFTINCREMENT 0x01
#define LCD_ENTRYSHIFTDECREMENT 0x00
// flags for display on/off control
#define LCD_DISPLAYON 0x04
#define LCD_DISPLAYOFF 0x00
#define LCD_CURSORON 0x02
#define LCD_CURSOROFF 0x00
#define LCD_BLINKON 0x01
#define LCD_BLINKOFF 0x00
// flags for display/cursor shift
#define LCD_DISPLAYMOVE 0x08
#define LCD_CURSORMOVE 0x00
#define LCD_MOVERIGHT 0x04
#define LCD_MOVELEFT 0x00
// flags for function set
#define LCD_8BITMODE 0x10
#define LCD_4BITMODE 0x00
#define LCD_2LINE 0x08
#define LCD_1LINE 0x00
#define LCD_5x10DOTS 0x04
#define LCD_5x8DOTS 0x00
class I2CLiquidCrystal : public Print {
public:
I2CLiquidCrystal();
I2CLiquidCrystal(uint8_t contrast, bool is5V);
void init();
void begin(uint8_t cols, uint8_t rows, uint8_t charsize = LCD_5x8DOTS);
void clear();
void home();
void noDisplay();
void display();
void noBlink();
void blink();
void noCursor();
void cursor();
void scrollDisplayLeft();
void scrollDisplayRight();
void leftToRight();
void rightToLeft();
void autoscroll();
void noAutoscroll();
void createChar(uint8_t, uint8_t[]);
void setCursor(uint8_t, uint8_t);
virtual size_t write(uint8_t);
void command(uint8_t);
using Print::write;
private:
void send(uint8_t, uint8_t);
bool _is5V;
uint8_t _contrast;
uint8_t _displayfunction;
uint8_t _displaycontrol;
uint8_t _displaymode;
uint8_t _initialized;
uint8_t _numlines,_currline;
uint8_t I2C_ADDR, I2C_RS;
};
#endif
Printクラスを継承している。
次にソース部分
・I2CLiquidCrystal.cpp
#include "I2CLiquidCrystal.h"
#include <stdio.h>
#include <string.h>
#include <inttypes.h>
#include <Wire.h>
#include "Arduino.h"
// When the display powers up, it is configured as follows:
//
// 1. Display clear
// 2. Function set:
// DL = 1; 8-bit interface data
// N = 0; 1-line display
// F = 0; 5x8 dot character font
// 3. Display on/off control:
// D = 0; Display off
// C = 0; Cursor off
// B = 0; Blinking off
// 4. Entry mode set:
// I/D = 1; Increment by 1
// S = 0; No shift
//
// Note, however, that resetting the Arduino doesn't reset the LCD, so we
// can't assume that its in that state when a sketch starts (and the
// I2CLiquidCrystal constructor is called).
// This library has been modified for I2C based LCD by Straberry Linux in Japan.
// The controller is ST7032i.
// 21 Aug. 2012, Noriaki Mitsunaga
const static uint8_t I2C_ADDR_AKIZUKI = 0x50;
I2CLiquidCrystal::I2CLiquidCrystal()
{
I2C_ADDR = I2C_ADDR_AKIZUKI; // Akizuki denshi
I2C_RS = 0x80;
init();
}
I2CLiquidCrystal::I2CLiquidCrystal(uint8_t contrast, bool is5V)
{
I2C_ADDR = 0x3e; // Strawberry Linux
I2C_RS = 0x40;
_contrast = contrast;
_is5V = is5V;
init();
}
void I2CLiquidCrystal::init()
{
Wire.begin();
_displayfunction = 0;
// begin(16, 1);
}
void I2CLiquidCrystal::begin(uint8_t cols, uint8_t lines, uint8_t dotsize) {
if (lines > 1) {
_displayfunction |= LCD_2LINE;
}
_numlines = lines;
_currline = 0;
// for some 1 line displays you can select a 10 pixel high font
if ((dotsize != 0) && (lines == 1)) {
_displayfunction |= LCD_5x10DOTS;
}
// SEE PAGE 45/46 FOR INITIALIZATION SPECIFICATION!
// according to datasheet, we need at least 40ms after power rises above 2.7V
// before sending commands. Arduino can turn on way befer 4.5V so we'll wait 50
delayMicroseconds(50000);
if (I2C_ADDR != I2C_ADDR_AKIZUKI) { // Strawberry Linux
// set # lines, font size, etc.
//command(0b00110000 | _displayfunction);
command(0x38); ★2
delayMicroseconds(50);
// again
//command(0b00110000 | _displayfunction);
command(0x39); ★2
delayMicroseconds(50);
// Internal OSC frequency
command(0x14); ★2
delayMicroseconds(50);
// Contrast set
command(0x70 | (_contrast & 0xF)); ★2
delayMicroseconds(50);
// Power/ICON/Contrast control
if (!_is5V) ★2
command(0x5c | ((_contrast >> 4) & 0x3));
else
command(0x58 | ((_contrast >> 4) & 0x3));
delayMicroseconds(50);
// Follower Control
command(0x6c); ★2
delay(400);
} else { // Akizuki LCD
command(0b00110000 | _displayfunction);
delayMicroseconds(4100);
command(0b00110000 | _displayfunction);
delayMicroseconds(100);
}
// Function set (set so as to be compatible with parallel LCD)
command(0b00110000 | _displayfunction);
// turn the display on with no cursor or blinking default
_displaycontrol = LCD_DISPLAYON | LCD_CURSOROFF | LCD_BLINKOFF;
display();
// clear it off
clear();
// Initialize to default text direction (for romance languages)
_displaymode = LCD_ENTRYLEFT | LCD_ENTRYSHIFTDECREMENT;
// set the entry mode
command(LCD_ENTRYMODESET | _displaymode);
}
/********** high level commands, for the user! */
void I2CLiquidCrystal::clear()
{
command(LCD_CLEARDISPLAY); // clear display, set cursor position to zero
delayMicroseconds(2000); // this command takes a long time!
}
void I2CLiquidCrystal::home()
{
command(LCD_RETURNHOME); // set cursor position to zero
delayMicroseconds(2000); // this command takes a long time!
}
void I2CLiquidCrystal::setCursor(uint8_t col, uint8_t row)
{
int row_offsets[] = { 0x00, 0x40, 0x14, 0x54 };
if ( row >= _numlines ) {
row = _numlines-1; // we count rows starting w/0
}
command(LCD_SETDDRAMADDR | (col + row_offsets[row]));
}
// Turn the display on/off (quickly)
void I2CLiquidCrystal::noDisplay() {
_displaycontrol &= ~LCD_DISPLAYON;
command(LCD_DISPLAYCONTROL | _displaycontrol);
}
void I2CLiquidCrystal::display() {
_displaycontrol |= LCD_DISPLAYON;
command(LCD_DISPLAYCONTROL | _displaycontrol);
}
// Turns the underline cursor on/off
void I2CLiquidCrystal::noCursor() {
_displaycontrol &= ~LCD_CURSORON;
command(LCD_DISPLAYCONTROL | _displaycontrol);
}
void I2CLiquidCrystal::cursor() {
_displaycontrol |= LCD_CURSORON;
command(LCD_DISPLAYCONTROL | _displaycontrol);
}
// Turn on and off the blinking cursor
void I2CLiquidCrystal::noBlink() {
_displaycontrol &= ~LCD_BLINKON;
command(LCD_DISPLAYCONTROL | _displaycontrol);
}
void I2CLiquidCrystal::blink() {
_displaycontrol |= LCD_BLINKON;
command(LCD_DISPLAYCONTROL | _displaycontrol);
}
// These commands scroll the display without changing the RAM
void I2CLiquidCrystal::scrollDisplayLeft(void) {
command(LCD_CURSORSHIFT | LCD_DISPLAYMOVE | LCD_MOVELEFT);
}
void I2CLiquidCrystal::scrollDisplayRight(void) {
command(LCD_CURSORSHIFT | LCD_DISPLAYMOVE | LCD_MOVERIGHT);
}
// This is for text that flows Left to Right
void I2CLiquidCrystal::leftToRight(void) {
_displaymode |= LCD_ENTRYLEFT;
command(LCD_ENTRYMODESET | _displaymode);
}
// This is for text that flows Right to Left
void I2CLiquidCrystal::rightToLeft(void) {
_displaymode &= ~LCD_ENTRYLEFT;
command(LCD_ENTRYMODESET | _displaymode);
}
// This will 'right justify' text from the cursor
void I2CLiquidCrystal::autoscroll(void) {
_displaymode |= LCD_ENTRYSHIFTINCREMENT;
command(LCD_ENTRYMODESET | _displaymode);
}
// This will 'left justify' text from the cursor
void I2CLiquidCrystal::noAutoscroll(void) {
_displaymode &= ~LCD_ENTRYSHIFTINCREMENT;
command(LCD_ENTRYMODESET | _displaymode);
}
// Allows us to fill the first 8 CGRAM locations
// with custom characters
void I2CLiquidCrystal::createChar(uint8_t location, uint8_t charmap[]) {
location &= 0x7; // we only have 8 locations 0-7
command(LCD_SETCGRAMADDR | (location << 3));
for (int i=0; i<8; i++) {
write(charmap[i]);
}
}
/*********** mid level commands, for sending data/cmds */
inline void I2CLiquidCrystal::command(uint8_t value) {
send(value, LOW);
}
inline size_t I2CLiquidCrystal::write(uint8_t value) {
send(value, HIGH);
return 1; // assume sucess
}
/************ low level data pushing commands **********/
// write either command or data, with automatic 4/8-bit selection
void I2CLiquidCrystal::send(uint8_t value, uint8_t mode) { ★1
Wire.beginTransmission(I2C_ADDR);
if (mode == LOW)
Wire.write(0x0); // Co = 0, RS = 0 // Co: continue
else
Wire.write(I2C_RS); // Co = 0, RS = 1
Wire.write(value);
Wire.endTransmission();
}
以下解析
★1
実際にコマンドを送る所。
Co : 0 -> 一回のコマンドで完結
Co : 1 -> 続きのコマンドがある
RS : 0 -> 設定系のコマンド時
RS : 1 -> データの読み書き時
★2
初期設定
初期化の流れとしては・・・
1. 電源電圧が安定してから40ms以上ウェイト
2. Function Set (0x38)
3. Function Set (0x39)
4. Internal OSC frequency(内部クロック周波数)
5. Contrast set
6. Power / ICON / Contrast constrol
7. Follower control
8. Display ON/OFF Control
