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1 // ---------------------------------------------------------------------------
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2 // Created by Francisco Malpartida on 20/08/11.
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3 // Copyright 2011 - Under creative commons license 3.0:
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4 // Attribution-ShareAlike CC BY-SA
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5 //
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6 // This software is furnished "as is", without technical support, and with no
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7 // warranty, express or implied, as to its usefulness for any purpose.
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8 //
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9 // Thread Safe: No
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10 // Extendable: Yes
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11 //
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12 // @file LiquidCrystal_SR.h
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13 // Connects an LCD using 2 or 3 pins from the Arduino, via an 8-bit
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14 // ShiftRegister (SR from now on).
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15 //
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16 // @brief
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17 // This is a port of the ShiftRegLCD library from raron and ported to the
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18 // LCD library.
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19 //
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20 // The functionality provided by this class and its base class is identical
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21 // to the original functionality of the Arduino LiquidCrystal library and can
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22 // be used as such.
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23 //
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24 // Modified to work serially with the shiftOut() function, an 8-bit
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25 // unlatched, no-tristate, unidirectional SIPO (Serial-In-Parallel-Out)
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26 // shift register (IE a very simple SR), and an LCD in 4-bit mode.
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27 // Any such shift register should do (pref. 74LS family IC's for 2-wire).
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28 // I used 74LS164, for the reason that's what I had at hand.
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29 //
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30 // Connection description:
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31 //
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32 // SR output:
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33 // Bit #0 - N/C - not connected, used to hold a zero
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34 // Bit #1 - N/C
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35 // Bit #2 - connects to RS (Register Select) on the LCD
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36 // Bits #3-6 - connects to LCD data inputs D4 - D7.
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37 // Bit #7 - enables the LCD enable-puls (via the diode-resistor AND "gate")
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38 //
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39 // 2 or 3 Pins required from the Arduino for Data, Clock and (optional) Enable
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40 // If not using Enable, the Data pin is used for the enable signal by defining
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41 // the same pin for Enable as for Data. Data and Clock outputs/pins goes to
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42 // the shiftregister.
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43 // LCD RW-pin hardwired to LOW (only writing to LCD).
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44 // Busy Flag (BF, data bit D7) is not read.
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45 //
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46 // Original project homepage: http://code.google.com/p/arduinoshiftreglcd/
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47 //
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48 //
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49 // History
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50 // 2012.03.29 bperrybap - Added delays for faster fio shiftout (it got too fast)
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51 // AVR needed delay. cmd/write delays are based on CPU speed so it works on pic32.
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52 // Added code to support indicating two wire mode by using enable=data pin
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53 // (documentation indicated this as working)
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54 // Fixed incorrect use of 5x10 for default font - now matches original LQ library.
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55 // can now eliminate enable pin in constructor for two wire mode.
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56 // 2012.01.16 Florian Fida - faster digitalWrite/shiftOut
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57 // 2011.10.29 fmalpartida - adaption of the library to the LCD class hierarchy.
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58 // 2011.07.02 Fixed a minor flaw in setCursor function. No functional change,
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59 // just a bit more memory efficient.
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60 // Thanks to CapnBry (from google code and github) who noticed it.
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61 // URL to his version of shiftregLCD:
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62 // https://github.com/CapnBry/HeaterMeter/commit/c6beba1b46b092ab0b33bcbd0a30a201fd1f28c1
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63 // 2009.07.30 raron - minor corrections to the comments.
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64 // Fixed timing to datasheet safe. Fixed keyword highlights.
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65 // 2009.07.28 Mircho / raron - a new modification to the schematics, and a
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66 // more streamlined interface
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67 // 2009.07.27 Thanks to an excellent suggestion from mircho at the Arduino
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68 // playgrond forum, the number of wires now required is only two!
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69 // 2009.07.25 raron - Fixed comments. I really messed up the comments before
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70 // posting this, so I had to fix it.
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71 // Renamed a function, but no improvements or functional changes.
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72 // 2009.07.23 Incorporated some proper initialization routines
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73 // inspired (lets say copy-paste-tweaked) from LiquidCrystal
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74 // library improvements from LadyAda.
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75 // 2009.05.23 raron - first version, but based mostly (as in almost verbatim)
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76 // on the "official" LiquidCrystal library.
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77 //
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78 //
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79 // @author F. Malpartida - fmalpartida@gmail.com
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80 // ---------------------------------------------------------------------------
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81 #include <stdio.h>
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82 #include <string.h>
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83 #include <inttypes.h>
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84
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85 #if (ARDUINO < 100)
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86 #include <WProgram.h>
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87 #else
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88 #include <Arduino.h>
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89 #endif
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90 #include "LiquidCrystal_SR.h"
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91
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92 #include "FastIO.h"
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93
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94
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95 // CONSTRUCTORS
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96 // ---------------------------------------------------------------------------
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97 // Assuming 1 line 8 pixel high font
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98 LiquidCrystal_SR::LiquidCrystal_SR (uint8_t srdata, uint8_t srclock,
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99 uint8_t enable )
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100 {
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101 init ( srdata, srclock, enable, 1, 0 );
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102 }
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103
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104
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105 // PRIVATE METHODS
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106 // ---------------------------------------------------------------------------
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107
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108 //
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109 // init
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110 void LiquidCrystal_SR::init(uint8_t srdata, uint8_t srclock, uint8_t enable,
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111 uint8_t lines, uint8_t font)
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112 {
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113 // Initialise private variables
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114 _two_wire = 0;
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115
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116 _srDataRegister = fio_pinToOutputRegister(srdata);
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117 _srDataBit = fio_pinToBit(srdata);
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118 _srClockRegister = fio_pinToOutputRegister(srclock);
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119 _srClockBit = fio_pinToBit(srclock);
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120
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121 if ((enable == TWO_WIRE) || (enable == srdata))
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122 {
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123 _two_wire = 1;
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124 _srEnableRegister = _srDataRegister;
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125 _srEnableBit = _srDataBit;
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126 }
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127 else
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128 {
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129 _srEnableRegister = fio_pinToOutputRegister(enable);
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130 _srEnableBit = fio_pinToBit(enable);
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131 }
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132
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133 // Configure control pins as outputs
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134 // ------------------------------------------------------------------------
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135
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136 _displayfunction = LCD_4BITMODE | LCD_1LINE | LCD_5x8DOTS;
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137 }
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138
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139 //
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140 // shiftIt
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141 void LiquidCrystal_SR::shiftIt(uint8_t val)
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142 {
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143 if (_two_wire)
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144 {
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145 // Clear to get Enable LOW
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146 fio_shiftOut(_srDataRegister, _srDataBit, _srClockRegister, _srClockBit);
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147 }
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148 fio_shiftOut(_srDataRegister, _srDataBit, _srClockRegister, _srClockBit, val, MSBFIRST);
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149
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150 // LCD ENABLE PULSE
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151 //
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152 // While this library is written with a shift register without an output
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153 // latch in mind, it can work in 3-wire mode with a shiftregister with a
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154 // latch. The shiftregister latch pin (STR, RCL or similar) is then
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155 // connected to the LCD enable pin. The LCD is (very likely) slower
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156 // to read the Enable pulse, and then reads the new contents of the SR.
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157 ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
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158 {
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159 fio_digitalWrite_HIGH(_srEnableRegister, _srEnableBit);
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160 waitUsec (1); // enable pulse must be >450ns
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161 fio_digitalWrite_SWITCHTO(_srEnableRegister, _srEnableBit, LOW);
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162 } // end critical section
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163 }
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164
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165 // PUBLIC METHODS
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166 // ---------------------------------------------------------------------------
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167
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168
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169 /************ low level data pushing commands **********/
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170 //
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171 // send
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172 void LiquidCrystal_SR::send(uint8_t value, uint8_t mode)
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173 {
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174 // Divide byte in two nibbles include the RS signal
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175 // and format it for shiftregister output wiring to the LCD
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176 // We are only interested in my COMMAND or DATA for myMode
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177 uint8_t myMode = ( mode == DATA ) ? SR_RS_BIT : 0; // RS bit; LOW: command. HIGH: character.
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178
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179 if ( mode != FOUR_BITS )
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180 {
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181 shiftIt(myMode | SR_EN_BIT | ((value >> 1) & 0x78)); // upper nibble
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182 }
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183
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184 shiftIt(myMode | SR_EN_BIT | ((value << 3) & 0x78)); // lower nibble
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185 /*
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186 * Add some delay since this code is so fast it needs some added delay
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187 * even on AVRs because the shiftout is shorter than the LCD command execution time.
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188 */
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189 #if (F_CPU <= 16000000)
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190 if(_two_wire)
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191 delayMicroseconds ( 10 );
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192 else
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193 delayMicroseconds ( 17 ); // 3 wire mode is faster so it must delay longer
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194 #else
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195 delayMicroseconds ( 37 ); // commands & data writes need > 37us to complete
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196 #endif
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197
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198 }
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199
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200 //
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201 // setBacklightPin
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202 void LiquidCrystal_SR::setBacklightPin ( uint8_t pin, t_backlighPol pol )
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203 { }
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204
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205 //
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206 // setBacklight
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207 void LiquidCrystal_SR::setBacklight ( uint8_t mode )
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208 { }
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209
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