faker 1968
/
Effector_110613
Embed:
(wiki syntax)
Show/hide line numbers
TextLCD.cpp
00001 /* draft mbed TextLCD 00002 * (c) 2007/8, sford 00003 */ 00004 00005 #include "TextLCD.h" 00006 00007 #include "mbed.h" 00008 00009 using namespace mbed; 00010 00011 /* 00012 * useful info found at http://www.a-netz.de/lcd.en.php 00013 * 00014 * 00015 * Initialisation 00016 * ============== 00017 * 00018 * After attaching the supply voltage/after a reset, the display needs to be brought in to a defined state 00019 * 00020 * - wait approximately 15 ms so the display is ready to execute commands 00021 * - Execute the command 0x30 ("Display Settings") three times (wait 1,64ms after each command, the busy flag cannot be queried now). 00022 * - The display is in 8 bit mode, so if you have only connected 4 data pins you should only transmit the higher nibble of each command. 00023 * - If you want to use the 4 bit mode, now you can execute the command to switch over to this mode now. 00024 * - Execute the "clear display" command 00025 * 00026 * Timing 00027 * ====== 00028 * 00029 * Nearly all commands transmitted to the display need 40us for execution. 00030 * Exceptions are the commands "Clear Display and Reset" and "Set Cursor to Start Position" 00031 * These commands need 1.64ms for execution. These timings are valid for all displays working with an 00032 * internal clock of 250kHz. But I do not know any displays that use other frequencies. Any time you 00033 * can use the busy flag to test if the display is ready to accept the next command. 00034 * 00035 * _e is kept high apart from calling clock 00036 * _rw is kept 0 (write) apart from actions that uyse it differently 00037 * _rs is set by the data/command writes 00038 */ 00039 00040 TextLCD::TextLCD(PinName rs, PinName rw, PinName e, PinName d0, PinName d1, 00041 PinName d2, PinName d3) : _rw(rw), _rs(rs), 00042 _e(e), _d(d0, d1, d2, d3){ 00043 00044 _rows = 4; 00045 _columns = 20; 00046 00047 _rw = 0; 00048 _e = 1; 00049 _rs = 0; // command mode 00050 00051 // Should theoretically wait 15ms, but most things will be powered up pre-reset 00052 // so i'll disable that for the minute. If implemented, could wait 15ms post reset 00053 // instead 00054 // wait(0.015); 00055 00056 // send "Display Settings" 3 times (Only top nibble of 0x30 as we've got 4-bit bus) 00057 for(int i=0; i<3; i++) { 00058 writeNibble(0x3); 00059 wait(0.00164); // this command takes 1.64ms, so wait for it 00060 } 00061 writeNibble(0x2); // 4-bit mode 00062 00063 writeCommand(0x28); // Function set 001 BW N F - - 00064 writeCommand(0x0C); 00065 writeCommand(0x6); // Cursor Direction and Display Shift : 0000 01 CD S (CD 0-left, 1-right S(hift) 0-no, 1-yes 00066 00067 cls(); 00068 } 00069 00070 int TextLCD::_putc(int value) { 00071 if(value == '\n') { 00072 newline(); 00073 } else { 00074 writeData(value); 00075 } 00076 return value; 00077 } 00078 00079 int TextLCD::_getc() { 00080 return 0; 00081 } 00082 00083 void TextLCD::newline() { 00084 _column = 0; 00085 _row++; 00086 if(_row >= _rows) { 00087 _row = 0; 00088 } 00089 locate(_column, _row); 00090 } 00091 00092 void TextLCD::locate(int column, int row) { 00093 if(column < 0 || column >= _columns || row < 0 || row >= _rows) { 00094 error("locate(%d,%d) out of range on %dx%d display", column, row, _columns, _rows); 00095 return; 00096 } 00097 00098 _row = row; 00099 _column = column; 00100 int address=0; 00101 // row 0 : 0x0->0x13 00102 // row 1 : 0x40->0x53 00103 // row 2 : 0x14->0x27 00104 // row 3 : 0x54->0x67 00105 00106 switch (_row) { 00107 case (0) : address = 0x00 + _column; 00108 break; 00109 case (1) : address = 0x40 + _column; 00110 break; 00111 case (2) : address = 0x14 + _column; 00112 break; 00113 case (3) : address = 0x54 + _column; 00114 break; 00115 } 00116 00117 address += 0x80; 00118 00119 // } 00120 // else { 00121 // memory starts at 0x80, and is 40 chars long per row 00122 // address = 0x80 + (_row * 40) + _column; 00123 // } 00124 00125 writeCommand(address); 00126 } 00127 00128 00129 void TextLCD::rows(int rows) { 00130 _rows = rows; 00131 } 00132 00133 00134 void TextLCD::columns(int columns) { 00135 _columns = columns; 00136 } 00137 00138 00139 00140 00141 void TextLCD::cls() { 00142 writeCommand(0x01); // Clear Display 00143 wait(0.00164f); // This command takes 1.64 ms 00144 locate(0, 0); 00145 } 00146 00147 void TextLCD::reset() { 00148 cls(); 00149 } 00150 00151 void TextLCD::clock() { 00152 wait(0.000040f); 00153 _e = 0; 00154 wait(0.000040f); // most instructions take 40us 00155 _e = 1; 00156 } 00157 00158 void TextLCD::writeNibble(int value) { 00159 _d = value; 00160 clock(); 00161 } 00162 00163 void TextLCD::writeByte(int value) { 00164 writeNibble(value >> 4); 00165 writeNibble(value >> 0); 00166 } 00167 00168 void TextLCD::writeCommand(int command) { 00169 _rs = 0; 00170 writeByte(command); 00171 } 00172 00173 void TextLCD::writeData(int data) { 00174 _rs = 1; 00175 writeByte(data); 00176 _column++; 00177 if(_column >= _columns) { 00178 newline(); 00179 } 00180 }
Generated on Sat Jul 16 2022 21:12:01 by 1.7.2