LCD Library 1.2.0
LCD Library - LCD control class hierarchy library. Drop in replacement for the LiquidCrystal Library.
/Users/fmalpartida/development/ardWorkspace/LiquidCrystal_I2C/LiquiCrystal_I2C/LiquidCrystal_SR.cpp
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00001 // ---------------------------------------------------------------------------
00002 // Created by Francisco Malpartida on 20/08/11.
00003 // Copyright 2011 - Under creative commons license 3.0:
00004 //        Attribution-ShareAlike CC BY-SA
00005 //
00006 // This software is furnished "as is", without technical support, and with no 
00007 // warranty, express or implied, as to its usefulness for any purpose.
00008 //
00009 // Thread Safe: No
00010 // Extendable: Yes
00011 //
00012 // @file LiquidCrystal_SR.h
00013 //  Connects an LCD using 2 or 3 pins from the Arduino, via an 8-bit 
00014 // ShiftRegister (SR from now on).
00015 // 
00016 // @brief 
00017 // This is a port of the ShiftRegLCD library from raron and ported to the
00018 // LCD library.
00019 //
00020 // The functionality provided by this class and its base class is identical
00021 // to the original functionality of the Arduino LiquidCrystal library and can
00022 // be used as such.
00023 //
00024 // Modified to work serially with the shiftOut() function, an 8-bit
00025 // unlatched, no-tristate, unidirectional SIPO (Serial-In-Parallel-Out)
00026 // shift register (IE a very simple SR), and an LCD in 4-bit mode.
00027 // Any such shift register should do (pref. 74LS family IC's for 2-wire).
00028 // I used 74LS164, for the reason that's what I had at hand.
00029 //
00030 // Connection description:
00031 //
00032 // SR output:
00033 // Bit  #0   - N/C - not connected, used to hold a zero
00034 // Bit  #1   - N/C
00035 // Bit  #2   - connects to RS (Register Select) on the LCD
00036 // Bits #3-6 - connects to LCD data inputs D4 - D7.
00037 // Bit  #7   - enables the LCD enable-puls (via the diode-resistor AND "gate")
00038 //
00039 // 2 or 3 Pins required from the Arduino for Data, Clock and (optional) Enable
00040 // If not using Enable, the Data pin is used for the enable signal by defining
00041 // the same pin for Enable as for Data. Data and Clock outputs/pins goes to
00042 // the shiftregister.
00043 // LCD RW-pin hardwired to LOW (only writing to LCD).
00044 // Busy Flag (BF, data bit D7) is not read.
00045 //
00046 //  Original project homepage: http://code.google.com/p/arduinoshiftreglcd/
00047 //
00048 //
00049 // History
00050 // 2012.01.16  Florian Fida - faster digitalWrite/shiftOut
00051 // 2011.10.29  fmalpartida - adaption of the library to the LCD class hierarchy.
00052 // 2011.07.02  Fixed a minor flaw in setCursor function. No functional change, 
00053 //             just a bit more memory efficient.
00054 //             Thanks to CapnBry (from google code and github) who noticed it.
00055 //             URL to his version of shiftregLCD:
00056 //             https://github.com/CapnBry/HeaterMeter/commit/c6beba1b46b092ab0b33bcbd0a30a201fd1f28c1
00057 // 2009.07.30  raron - minor corrections to the comments.
00058 //             Fixed timing to datasheet safe. Fixed keyword highlights.
00059 // 2009.07.28  Mircho / raron - a new modification to the schematics, and a
00060 //             more streamlined interface
00061 // 2009.07.27  Thanks to an excellent suggestion from mircho at the Arduino
00062 //             playgrond forum, the number of wires now required is only two!
00063 // 2009.07.25  raron - Fixed comments. I really messed up the comments before 
00064 //             posting this, so I had to fix it.
00065 //             Renamed a function, but no improvements or functional changes.
00066 // 2009.07.23  Incorporated some proper initialization routines
00067 //             inspired (lets say copy-paste-tweaked) from LiquidCrystal
00068 //             library improvements from LadyAda.
00069 // 2009.05.23  raron - first version, but based mostly (as in almost verbatim)
00070 //             on the "official" LiquidCrystal library.
00071 //
00072 //
00073 // @author F. Malpartida - fmalpartida@gmail.com
00074 // ---------------------------------------------------------------------------
00075 #include <stdio.h>
00076 #include <string.h>
00077 #include <inttypes.h>
00078 
00079 #if (ARDUINO <  100)
00080 #include <WProgram.h>
00081 #else
00082 #include <Arduino.h>
00083 #endif
00084 #include "LiquidCrystal_SR.h"
00085 
00086 #include "FastIO.h"
00087 
00088 
00089 // CONSTRUCTORS
00090 // ---------------------------------------------------------------------------
00091 // Assuming 1 line 8 pixel high font
00092 LiquidCrystal_SR::LiquidCrystal_SR ( uint8_t srdata, uint8_t srclock, 
00093                                      uint8_t enable ) 
00094 {
00095         init ( srdata, srclock, enable, 1, 0 );
00096 }
00097 
00098 
00099 // PRIVATE METHODS
00100 // ---------------------------------------------------------------------------
00101 
00102 //
00103 // init
00104 void LiquidCrystal_SR::init(uint8_t srdata, uint8_t srclock, uint8_t enable, uint8_t lines, uint8_t font)
00105 {
00106    // Initialise private variables
00107    _two_wire = 0;
00108 
00109    _srDataRegister = fio_pinToOutputRegister(srdata);
00110    _srDataBit = fio_pinToBit(srdata);
00111    _srClockRegister = fio_pinToOutputRegister(srclock);
00112    _srClockBit = fio_pinToBit(srclock);
00113 
00114    if (enable == TWO_WIRE)
00115    {
00116       _two_wire = 1;
00117       _srEnableRegister = _srDataRegister;
00118       _srEnableBit = _srDataBit;
00119    }
00120    else
00121    {
00122       _srEnableRegister = fio_pinToOutputRegister(enable);
00123       _srEnableBit = fio_pinToBit(enable);
00124    }
00125 
00126    // Configure control pins as outputs
00127    // ------------------------------------------------------------------------
00128 
00129    _displayfunction = LCD_4BITMODE | LCD_1LINE | LCD_5x10DOTS;
00130 }
00131 
00132 // shiftIt
00133 void LiquidCrystal_SR::shiftIt(uint8_t val)
00134 {
00135    if (_two_wire)
00136    {
00137       // Clear to get Enable LOW
00138       fio_shiftOut(_srDataRegister, _srDataBit, _srClockRegister, _srClockBit);
00139    }
00140    fio_shiftOut(_srDataRegister, _srDataBit, _srClockRegister, _srClockBit, val, MSBFIRST);
00141 
00142    // LCD ENABLE PULSE
00143    //
00144    // While this library is written with a shift register without an output
00145    // latch in mind, it can work in 3-wire mode with a shiftregister with a
00146    // latch. The shiftregister latch pin (STR, RCL or similar) is then
00147    // connected to the LCD enable pin. The LCD is (very likely) slower
00148    // to read the Enable pulse, and then reads the new contents of the SR.
00149    fio_digitalWrite_HIGH(_srEnableRegister, _srEnableBit);
00150    waitUsec (1);         // enable pulse must be >450ns               
00151    fio_digitalWrite_SWITCHTO(_srEnableRegister, _srEnableBit, LOW);
00152    waitUsec ( 37 );      // commands need > 37us to settle
00153 }
00154 
00155 // PUBLIC METHODS
00156 // ---------------------------------------------------------------------------
00157 
00158 
00159 /************ low level data pushing commands **********/
00160 
00161 // send
00162 void LiquidCrystal_SR::send(uint8_t value, uint8_t mode)
00163 {
00164    // Divide byte in two nibbles include the RS signal
00165    // and format it for shiftregister output wiring to the LCD
00166    mode = mode ? SR_RS_BIT : 0; // RS bit; LOW: command.  HIGH: character.
00167    shiftIt(mode | SR_EN_BIT | ((value >> 1) & 0x78)); // upper nibble
00168    shiftIt(mode | SR_EN_BIT | ((value << 3) & 0x78)); // lower nibble
00169 }
00170 
00171 //
00172 // setBacklight
00173 void LiquidCrystal_SR::setBacklight ( uint8_t mode ) 
00174 { }
00175 
00176 
00177 void LiquidCrystal_SR::setBacklightPin ( uint8_t pin )
00178 { }
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