LCD Library 1.3.0
LCD Library - LCD control class hierarchy library. Drop in replacement for the LiquidCrystal Library.
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 // 2012.03.29  bperrybap - Added delays for faster fio shiftout (it got too fast)
00051 //             AVR needed delay. cmd/write delays are based on CPU speed so it works on pic32.
00052 //             Added code to support indicating two wire mode by using enable=data pin
00053 //             (documentation indicated this as working)
00054 //             Fixed incorrect use of 5x10 for default font - now matches original LQ library.
00055 //             can now eliminate enable pin in constructor for two wire mode.
00056 // 2012.01.16  Florian Fida - faster digitalWrite/shiftOut
00057 // 2011.10.29  fmalpartida - adaption of the library to the LCD class hierarchy.
00058 // 2011.07.02  Fixed a minor flaw in setCursor function. No functional change, 
00059 //             just a bit more memory efficient.
00060 //             Thanks to CapnBry (from google code and github) who noticed it.
00061 //             URL to his version of shiftregLCD:
00062 //             https://github.com/CapnBry/HeaterMeter/commit/c6beba1b46b092ab0b33bcbd0a30a201fd1f28c1
00063 // 2009.07.30  raron - minor corrections to the comments.
00064 //             Fixed timing to datasheet safe. Fixed keyword highlights.
00065 // 2009.07.28  Mircho / raron - a new modification to the schematics, and a
00066 //             more streamlined interface
00067 // 2009.07.27  Thanks to an excellent suggestion from mircho at the Arduino
00068 //             playgrond forum, the number of wires now required is only two!
00069 // 2009.07.25  raron - Fixed comments. I really messed up the comments before 
00070 //             posting this, so I had to fix it.
00071 //             Renamed a function, but no improvements or functional changes.
00072 // 2009.07.23  Incorporated some proper initialization routines
00073 //             inspired (lets say copy-paste-tweaked) from LiquidCrystal
00074 //             library improvements from LadyAda.
00075 // 2009.05.23  raron - first version, but based mostly (as in almost verbatim)
00076 //             on the "official" LiquidCrystal library.
00077 //
00078 //
00079 // @author F. Malpartida - fmalpartida@gmail.com
00080 // ---------------------------------------------------------------------------
00081 #include <stdio.h>
00082 #include <string.h>
00083 #include <inttypes.h>
00084 
00085 #if (ARDUINO <  100)
00086 #include <WProgram.h>
00087 #else
00088 #include <Arduino.h>
00089 #endif
00090 #include "LiquidCrystal_SR.h"
00091 
00092 #include "FastIO.h"
00093 
00094 
00095 // CONSTRUCTORS
00096 // ---------------------------------------------------------------------------
00097 // Assuming 1 line 8 pixel high font
00098 LiquidCrystal_SR::LiquidCrystal_SR (uint8_t srdata, uint8_t srclock, 
00099                                     uint8_t enable ) 
00100 {
00101         init ( srdata, srclock, enable, 1, 0 );
00102 }
00103 
00104 
00105 // PRIVATE METHODS
00106 // ---------------------------------------------------------------------------
00107 
00108 //
00109 // init
00110 void LiquidCrystal_SR::init(uint8_t srdata, uint8_t srclock, uint8_t enable, 
00111                             uint8_t lines, uint8_t font)
00112 {
00113    // Initialise private variables
00114    _two_wire = 0;
00115    
00116    _srDataRegister = fio_pinToOutputRegister(srdata);
00117    _srDataBit = fio_pinToBit(srdata);
00118    _srClockRegister = fio_pinToOutputRegister(srclock);
00119    _srClockBit = fio_pinToBit(srclock);
00120    
00121    if ((enable == TWO_WIRE) || (enable == srdata))
00122    {
00123       _two_wire = 1;
00124       _srEnableRegister = _srDataRegister;
00125       _srEnableBit = _srDataBit;
00126    }
00127    else
00128    {
00129       _srEnableRegister = fio_pinToOutputRegister(enable);
00130       _srEnableBit = fio_pinToBit(enable);
00131    }
00132    
00133    // Configure control pins as outputs
00134    // ------------------------------------------------------------------------
00135    
00136    _displayfunction = LCD_4BITMODE | LCD_1LINE | LCD_5x8DOTS;
00137 }
00138 
00139 //
00140 // shiftIt
00141 void LiquidCrystal_SR::shiftIt(uint8_t val)
00142 {
00143    if (_two_wire)
00144    {
00145       // Clear to get Enable LOW
00146       fio_shiftOut(_srDataRegister, _srDataBit, _srClockRegister, _srClockBit);
00147    }
00148    fio_shiftOut(_srDataRegister, _srDataBit, _srClockRegister, _srClockBit, val, MSBFIRST);
00149    
00150    // LCD ENABLE PULSE
00151    //
00152    // While this library is written with a shift register without an output
00153    // latch in mind, it can work in 3-wire mode with a shiftregister with a
00154    // latch. The shiftregister latch pin (STR, RCL or similar) is then
00155    // connected to the LCD enable pin. The LCD is (very likely) slower
00156    // to read the Enable pulse, and then reads the new contents of the SR.
00157    ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
00158    {
00159       fio_digitalWrite_HIGH(_srEnableRegister, _srEnableBit);
00160       delayMicroseconds (1);         // enable pulse must be >450ns               
00161       fio_digitalWrite_SWITCHTO(_srEnableRegister, _srEnableBit, LOW);
00162    } // end critical section
00163 }
00164 
00165 // PUBLIC METHODS
00166 // ---------------------------------------------------------------------------
00167 
00168 
00169 /************ low level data pushing commands **********/
00170 //
00171 // send
00172 void LiquidCrystal_SR::send(uint8_t value, uint8_t mode)
00173 {
00174    // Divide byte in two nibbles include the RS signal
00175    // and format it for shiftregister output wiring to the LCD
00176    // We are only interested in my COMMAND or DATA for myMode
00177    uint8_t myMode = ( mode == DATA ) ? SR_RS_BIT : 0; // RS bit; LOW: command.  HIGH: character.
00178    
00179    if ( mode != FOUR_BITS )
00180    {
00181       shiftIt(myMode | SR_EN_BIT | ((value >> 1) & 0x78)); // upper nibble
00182    }
00183 
00184    shiftIt(myMode | SR_EN_BIT | ((value << 3) & 0x78)); // lower nibble
00185    /*
00186     * Add some delay since this code is so fast it needs some added delay
00187     * even on AVRs because the shiftout is shorter than the LCD command execution time.
00188     */
00189 #if (F_CPU <= 16000000)
00190    if(_two_wire)
00191         delayMicroseconds ( 10 );
00192    else
00193         delayMicroseconds ( 17 ); // 3 wire mode is faster so it must delay longer
00194 #else
00195    delayMicroseconds ( 37 );      // commands & data writes need > 37us to complete
00196 #endif
00197 
00198 }
00199 
00200 //
00201 // setBacklightPin
00202 void LiquidCrystal_SR::setBacklightPin ( uint8_t pin, t_backlighPol pol )
00203 { }
00204 
00205 //
00206 // setBacklight
00207 void LiquidCrystal_SR::setBacklight ( uint8_t mode ) 
00208 { }
00209 
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