Tomo SEEC
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mbed-mX-USB-TEST1
Test USB
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TextLCD.cpp
00001 /* mbed TextLCD Library 00002 * Copyright (c) 2007-2009 sford 00003 * Released under the MIT License: http://mbed.org/license/mit 00004 * 00005 * TODO: Needs serious rework/neatening up! 00006 */ 00007 00008 #include "TextLCD.h" 00009 00010 #include "mbed.h" 00011 #include "error.h" 00012 00013 using namespace mbed; 00014 00015 /* 00016 * useful info found at http://www.a-netz.de/lcd.en.php 00017 * 00018 * 00019 * Initialisation 00020 * ============== 00021 * 00022 * After attaching the supply voltage/after a reset, the display needs to be brought in to a defined state 00023 * 00024 * - wait approximately 15 ms so the display is ready to execute commands 00025 * - Execute the command 0x30 ("Display Settings") three times (wait 1,64ms after each command, the busy flag cannot be queried now). 00026 * - 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. 00027 * - If you want to use the 4 bit mode, now you can execute the command to switch over to this mode now. 00028 * - Execute the "clear display" command 00029 * 00030 * Timing 00031 * ====== 00032 * 00033 * Nearly all commands transmitted to the display need 40us for execution. 00034 * Exceptions are the commands "Clear Display and Reset" and "Set Cursor to Start Position" 00035 * These commands need 1.64ms for execution. These timings are valid for all displays working with an 00036 * internal clock of 250kHz. But I do not know any displays that use other frequencies. Any time you 00037 * can use the busy flag to test if the display is ready to accept the next command. 00038 * 00039 * _e is kept high apart from calling clock 00040 * _rw is kept 0 (write) apart from actions that uyse it differently 00041 * _rs is set by the data/command writes 00042 */ 00043 00044 TextLCD::TextLCD(PinName rs, PinName rw, PinName e, PinName d0, PinName d1, 00045 PinName d2, PinName d3, int columns, int rows) : _rw(rw), _rs(rs), 00046 _e(e), _d(d0, d1, d2, d3), _columns(columns), _rows(rows) { 00047 00048 // _rows = 2; 00049 // _columns = 16; 00050 // Mon, 27 Apr 2009 23:32:34 +0200 00051 // Kevin Konradt: 00052 // When using a LCD with 1 row x 16 characters 00053 // instead of 2x16, try changing _columns to 8. 00054 // (display seems to split the 16 characters into 00055 // 2 virtual rows with 8 characters each.) 00056 00057 _rw = 0; 00058 _e = 1; 00059 _rs = 0; // command mode 00060 00061 // Should theoretically wait 15ms, but most things will be powered up pre-reset 00062 // so i'll disable that for the minute. If implemented, could wait 15ms post reset 00063 // instead 00064 // wait(0.015); 00065 00066 // send "Display Settings" 3 times (Only top nibble of 0x30 as we've got 4-bit bus) 00067 for(int i=0; i<3; i++) { 00068 writeNibble(0x3); 00069 wait(0.00164); // this command takes 1.64ms, so wait for it 00070 } 00071 writeNibble(0x2); // 4-bit mode 00072 00073 writeCommand(0x28); // Function set 001 BW N F - - 00074 writeCommand(0x0C); 00075 writeCommand(0x6); // Cursor Direction and Display Shift : 0000 01 CD S (CD 0-left, 1-right S(hift) 0-no, 1-yes 00076 00077 cls(); 00078 } 00079 00080 int TextLCD::_putc(int value) { 00081 if(value == '\n') { 00082 newline(); 00083 } else { 00084 writeData(value); 00085 } 00086 return value; 00087 } 00088 00089 int TextLCD::_getc() { 00090 return 0; 00091 } 00092 00093 void TextLCD::newline() { 00094 _column = 0; 00095 _row++; 00096 if(_row >= _rows) { 00097 _row = 0; 00098 } 00099 locate(_column, _row); 00100 } 00101 00102 void TextLCD::locate(int column, int row) { 00103 if(column < 0 || column >= _columns || row < 0 || row >= _rows) { 00104 error("locate(%d,%d) out of range on %dx%d display", column, row, _columns, _rows); 00105 return; 00106 } 00107 00108 _row = row; 00109 _column = column; 00110 int address = 0x80 + (_row * 40) + _column; // memory starts at 0x80, and is 40 chars long per row 00111 writeCommand(address); 00112 } 00113 00114 void TextLCD::cls() { 00115 writeCommand(0x01); // Clear Display 00116 wait(0.00164f); // This command takes 1.64 ms 00117 locate(0, 0); 00118 } 00119 00120 void TextLCD::reset() { 00121 cls(); 00122 } 00123 00124 void TextLCD::clock() { 00125 wait(0.000040f); 00126 _e = 0; 00127 wait(0.000040f); // most instructions take 40us 00128 _e = 1; 00129 } 00130 00131 void TextLCD::writeNibble(int value) { 00132 _d = value; 00133 clock(); 00134 } 00135 00136 void TextLCD::writeByte(int value) { 00137 writeNibble(value >> 4); 00138 writeNibble(value >> 0); 00139 } 00140 00141 void TextLCD::writeCommand(int command) { 00142 _rs = 0; 00143 writeByte(command); 00144 } 00145 00146 void TextLCD::writeData(int data) { 00147 _rs = 1; 00148 writeByte(data); 00149 _column++; 00150 if(_column >= _columns) { 00151 newline(); 00152 } 00153 }
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