Source

New LiquidCrystal / LiquidCrystal_SR.cpp

The default branch has multiple heads

Full commit
// ---------------------------------------------------------------------------
// Created by Francisco Malpartida on 20/08/11.
// Copyright 2011 - Under creative commons license 3.0:
//        Attribution-ShareAlike CC BY-SA
//
// This software is furnished "as is", without technical support, and with no 
// warranty, express or implied, as to its usefulness for any purpose.
//
// Thread Safe: No
// Extendable: Yes
//
// @file LiquidCrystal_SR.h
//  Connects an LCD using 2 or 3 pins from the Arduino, via an 8-bit 
// ShiftRegister (SR from now on).
// 
// @brief 
// This is a port of the ShiftRegLCD library from raron and ported to the
// LCD library.
//
// The functionality provided by this class and its base class is identical
// to the original functionality of the Arduino LiquidCrystal library and can
// be used as such.
//
// Modified to work serially with the shiftOut() function, an 8-bit
// unlatched, no-tristate, unidirectional SIPO (Serial-In-Parallel-Out)
// shift register (IE a very simple SR), and an LCD in 4-bit mode.
// Any such shift register should do (pref. 74LS family IC's for 2-wire).
// I used 74LS164, for the reason that's what I had at hand.
//
// Connection description:
//
// SR output:
// Bit  #0   - N/C - not connected, used to hold a zero
// Bit  #1   - N/C
// Bit  #2   - connects to RS (Register Select) on the LCD
// Bits #3-6 - connects to LCD data inputs D4 - D7.
// Bit  #7   - enables the LCD enable-puls (via the diode-resistor AND "gate")
//
// 2 or 3 Pins required from the Arduino for Data, Clock and (optional) Enable
// If not using Enable, the Data pin is used for the enable signal by defining
// the same pin for Enable as for Data. Data and Clock outputs/pins goes to
// the shiftregister.
// LCD RW-pin hardwired to LOW (only writing to LCD).
// Busy Flag (BF, data bit D7) is not read.
//
//  Original project homepage: http://code.google.com/p/arduinoshiftreglcd/
//
//
// History
// 2011.10.29  fmalpartida - adaption of the library to the LCD class hierarchy.
// 2011.07.02  Fixed a minor flaw in setCursor function. No functional change, 
//             just a bit more memory efficient.
//             Thanks to CapnBry (from google code and github) who noticed it.
//             URL to his version of shiftregLCD:
//             https://github.com/CapnBry/HeaterMeter/commit/c6beba1b46b092ab0b33bcbd0a30a201fd1f28c1
// 2009.07.30  raron - minor corrections to the comments.
//             Fixed timing to datasheet safe. Fixed keyword highlights.
// 2009.07.28  Mircho / raron - a new modification to the schematics, and a
//             more streamlined interface
// 2009.07.27  Thanks to an excellent suggestion from mircho at the Arduiono 
//             playgrond forum, the number of wires now required is only two!
// 2009.07.25  raron - Fixed comments. I really messed up the comments before 
//             posting this, so I had to fix it.
//             Renamed a function, but no improvements or functional changes.
// 2009.07.23  Incorporated some proper initialization routines
//             inspired (lets say copy-paste-tweaked) from LiquidCrystal
//             library improvements from LadyAda.
// 2009.05.23  raron - first version, but based mostly (as in almost verbatim)
//             on the "official" LiquidCrystal library.
//
//
// This library is only compatible with Arduino's SDK version 1.0
//
//
// @author F. Malpartida - fmalpartida@gmail.com
// ---------------------------------------------------------------------------
#include <stdio.h>
#include <string.h>
#include <inttypes.h>

#if (ARDUINO <  100)
#include <WProgram.h>
#else
#include <Arduino.h>
#endif
#include <LiquidCrystal_SR.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
// LiquidCrystal constructor is called).
// A call to begin() will reinitialize the LCD.

// STATIC helper functions
// ---------------------------------------------------------------------------


// CONSTRUCTORS
// ---------------------------------------------------------------------------
// Assuming 1 line 8 pixel high font
LiquidCrystal_SR::LiquidCrystal_SR ( uint8_t srdata, uint8_t srclock, 
                                     uint8_t enable ) 
{
	init ( srdata, srclock, enable, 1, 0 );
}



// PRIVATE METHODS
// ---------------------------------------------------------------------------

//
// init
void LiquidCrystal_SR::init( uint8_t srdata, uint8_t srclock, uint8_t enable, 
                             uint8_t lines, uint8_t font )
{
   // Initialise private variables
   _two_wire    = 0;
   _srdata_pin  = srdata; 
   _srclock_pin = srclock; 
   _enable_pin  = enable;
   
   if (enable == TWO_WIRE)
   {
      _enable_pin = _srdata_pin;
      _two_wire   = 1;
   }
   
   // Configure control pins as outputs
   // ------------------------------------------------------------------------
   pinMode(_srclock_pin, OUTPUT);
   pinMode(_srdata_pin, OUTPUT);
   pinMode(_enable_pin, OUTPUT);
   
   _displayfunction = LCD_4BITMODE | LCD_1LINE | LCD_5x10DOTS;
}

// PUBLIC METHODS
// ---------------------------------------------------------------------------

//
// begin
void LiquidCrystal_SR::begin(uint8_t cols, uint8_t lines, uint8_t dotsize) 
{
   
   if (lines > 1) 
   {
      _displayfunction |= LCD_2LINE;
   }

   _numlines = lines;
   _cols = cols;
   
   // 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 before 4.5V so we'll wait 
   // 50
   // ---------------------------------------------------------------------------
   delayMicroseconds(50000);
   write4bits(LCD_FUNCTIONSET | LCD_8BITMODE);
   delayMicroseconds(4500);  // wait more than 4.1ms
   
   // Second try
   write4bits(LCD_FUNCTIONSET | LCD_8BITMODE);
   delayMicroseconds(150);
   // Third go
   write4bits(LCD_FUNCTIONSET | LCD_8BITMODE);
   
   // And finally, set to 4-bit interface
   write4bits(LCD_FUNCTIONSET | LCD_4BITMODE);
   
   // Set # lines, font size, etc.
   command(LCD_FUNCTIONSET | _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);
   home();
   
}

/************ low level data pushing commands **********/

// send
void LiquidCrystal_SR::send(uint8_t value, uint8_t mode) 
{
   uint8_t val1, val2;
   
   // If _two_wire - clear the shiftregister first.
   // ----------------------------------------------
   if ( _two_wire ) 
   {
      shiftOut ( _srdata_pin, _srclock_pin, MSBFIRST, 0x00 );
   }
   digitalWrite( _enable_pin, LOW );
   
   // Divide byte in two nibbles (val1 and val2), include the RS signal
   // and format it for shiftregister output wiring to the LCD
   mode = mode ? SR_RS_BIT : 0; // RS bit; LOW: command.  HIGH: character.
   val1 = mode | SR_EN_BIT | ((value >> 1) & 0x78); // upper nibble
   val2 = mode | SR_EN_BIT | ((value << 3) & 0x78); // lower nibble
   
   shiftOut ( _srdata_pin, _srclock_pin, MSBFIRST, val1 );
   
   // LCD ENABLE PULSE
   //
   // While this library is written with a shift register without an output
   // latch in mind, it can work in 3-wire mode with a shiftregister with a
   // latch. The shiftregister latch pin (STR, RCL or similar) is then
   // connected to the LCD enable pin. The LCD is (very likely) slower
   // to read the Enable pulse, and then reads the new contents of the SR.
   digitalWrite( _enable_pin, HIGH );
   waitUsec( 1 );                 // enable pulse must be >450ns
   digitalWrite( _enable_pin, LOW );

   // clear shiftregister
   // ---------------------------
   if ( _two_wire ) 
   {
      shiftOut ( _srdata_pin, _srclock_pin, MSBFIRST, 0x00 ); 
   }
   shiftOut ( _srdata_pin, _srclock_pin, MSBFIRST, val2 );
   
   // LCD ENABLE PULSE, se above comment
   digitalWrite( _enable_pin, HIGH );
   waitUsec( 1 );                 // enable pulse must be >450ns
   digitalWrite( _enable_pin, LOW );
   waitUsec( 40 );                // commands need > 37us to settle
}

//
// write4bits
void LiquidCrystal_SR::write4bits(uint8_t value) 
{
   uint8_t val1;
   
   // clear shiftregister
   // --------------------------
   if ( _two_wire ) 
   {
      shiftOut ( _srdata_pin, _srclock_pin, MSBFIRST, 0x00 ); 
   }
   digitalWrite( _enable_pin, LOW );

   // Discard lower nibble
   // and format it for shiftregister output wiring to the LCD
   val1 = SR_EN_BIT | ((value >> 1) & 0x78);
   shiftOut ( _srdata_pin, _srclock_pin, MSBFIRST, val1 );

   // LCD ENABLE PULSE
   //
   // While this library is written with a shift register without an output
   // latch in mind, it can work in 3-wire mode with a shiftregister with a
   // latch. The shiftregister latch pin (STR, RCL or similar) is then
   // connected to the LCD enable pin. The LCD is (very likely) slower
   // to read the Enable pulse, and then reads the new contents of the SR.
   digitalWrite( _enable_pin, HIGH );
   waitUsec( 1 );                 // enable pulse must be >450ns
   digitalWrite( _enable_pin, LOW );
   
   waitUsec( 40 );               // commands need > 37us to settle
}