Louis Lagendijk L / TextDisplays

A TextDisplay driver that supports graphical displays using on of the SED133x conrtrolers. Allows stdout and stderr output to be redirected to the display.

TextLCD.cpp@9:68ad299df12b, 2011-01-29 (annotated)

Committer:
llagendijk
Date:
Sat Jan 29 21:28:42 2011 +0000
Revision:
9:68ad299df12b
Parent:
1:18c56f038905 
First release of my version of TextDisPlay

Who changed what in which revision?

UserRevisionLine numberNew contents of line
llagendijk 0:9e72c57b16fd 1 /* mbed TextLCD Library
llagendijk 0:9e72c57b16fd 2 * Copyright (c) 2007-2009 sford
llagendijk 0:9e72c57b16fd 3 * Released under the MIT License: http://mbed.org/license/mit
llagendijk 0:9e72c57b16fd 4 *
llagendijk 0:9e72c57b16fd 5 * Modified by Ned Konz to provide better support for 4-line LCDs and ones with other controller chips.
llagendijk 0:9e72c57b16fd 6 */
llagendijk 0:9e72c57b16fd 7
llagendijk 0:9e72c57b16fd 8 #include "TextLCD.h"
llagendijk 0:9e72c57b16fd 9 #include "mbed.h"
llagendijk 0:9e72c57b16fd 10
llagendijk 0:9e72c57b16fd 11 /*
llagendijk 0:9e72c57b16fd 12 * useful info found at http://www.a-netz.de/lcd.en.php
llagendijk 0:9e72c57b16fd 13 *
llagendijk 0:9e72c57b16fd 14 * Initialisation
llagendijk 0:9e72c57b16fd 15 * ==============
llagendijk 0:9e72c57b16fd 16 *
llagendijk 0:9e72c57b16fd 17 * After attaching the supply voltage/after a reset, the display needs to be brought in to a defined state
llagendijk 0:9e72c57b16fd 18 *
llagendijk 0:9e72c57b16fd 19 * - wait approximately 15 ms so the display is ready to execute commands
llagendijk 0:9e72c57b16fd 20 * - Execute the command 0x30 ("Display Settings") three times (wait 1,64ms after each command, the busy flag cannot be queried now).
llagendijk 0:9e72c57b16fd 21 * - 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.
llagendijk 0:9e72c57b16fd 22 * - If you want to use the 4 bit mode, now you can execute the command to switch over to this mode now.
llagendijk 0:9e72c57b16fd 23 * - Execute the "clear display" command
llagendijk 0:9e72c57b16fd 24 *
llagendijk 0:9e72c57b16fd 25 * Timing
llagendijk 0:9e72c57b16fd 26 * ======
llagendijk 0:9e72c57b16fd 27 *
llagendijk 0:9e72c57b16fd 28 * Nearly all commands transmitted to the display need 40us for execution.
llagendijk 0:9e72c57b16fd 29 * Exceptions are the commands "Clear Display and Reset" and "Set Cursor to Start Position"
llagendijk 0:9e72c57b16fd 30 * These commands need 1.64ms for execution. These timings are valid for all displays working with an
llagendijk 0:9e72c57b16fd 31 * internal clock of 250kHz. But I do not know any displays that use other frequencies. Any time you
llagendijk 0:9e72c57b16fd 32 * can use the busy flag to test if the display is ready to accept the next command.
llagendijk 0:9e72c57b16fd 33 *
llagendijk 0:9e72c57b16fd 34 * _e is kept low except when being used.
llagendijk 0:9e72c57b16fd 35 * _rw is kept 0 (write) apart from actions that use it differently
llagendijk 0:9e72c57b16fd 36 * _rs is set by the data/command writes
llagendijk 0:9e72c57b16fd 37 */
llagendijk 0:9e72c57b16fd 38
llagendijk 0:9e72c57b16fd 39 TextLCD::TextLCD(PinName rs, PinName rw, PinName e, PinName d0, PinName d1,
llagendijk 1:18c56f038905 40 PinName d2, PinName d3, uint16_t rows, uint16_t cols, const char *name) :
llagendijk 1:18c56f038905 41 TextDisplay(name), _rw(rw), _rs(rs),
llagendijk 0:9e72c57b16fd 42 _e(e), _d(d0, d1, d2, d3), _rows(rows), _columns(cols) {
llagendijk 0:9e72c57b16fd 43
llagendijk 0:9e72c57b16fd 44 _rw = 0;
llagendijk 0:9e72c57b16fd 45 wait_us(1); // min. 100nsec delay
llagendijk 0:9e72c57b16fd 46 _e = 0;
llagendijk 0:9e72c57b16fd 47 _rs = 0; // command mode
llagendijk 0:9e72c57b16fd 48 _d.output();
llagendijk 0:9e72c57b16fd 49
llagendijk 0:9e72c57b16fd 50 reset();
llagendijk 0:9e72c57b16fd 51 cls();
llagendijk 0:9e72c57b16fd 52 }
llagendijk 0:9e72c57b16fd 53
llagendijk 0:9e72c57b16fd 54 void TextLCD::reset() {
llagendijk 0:9e72c57b16fd 55 wait_ms(15);
llagendijk 0:9e72c57b16fd 56 // e is low at this point, as is rw.
llagendijk 0:9e72c57b16fd 57 // 2. Send 0x3 and wait 150 ms (will stay in 8-bit mode if already there)
llagendijk 0:9e72c57b16fd 58 writeHalfByte(0x3);
llagendijk 0:9e72c57b16fd 59 wait_ms(5);
llagendijk 0:9e72c57b16fd 60 // 3. Send 0x3 and wait 150 ms (will go to 8-bit mode if was in 4-bit without any garbage nibble)
llagendijk 0:9e72c57b16fd 61 writeHalfByte(0x3);
llagendijk 0:9e72c57b16fd 62 wait_ms(5);
llagendijk 0:9e72c57b16fd 63 // 4. Send 0x3 and wait 250 ms (will go to 8-bit mode even if garbage nibble was previously received)
llagendijk 0:9e72c57b16fd 64 writeHalfByte(0x3);
llagendijk 0:9e72c57b16fd 65 wait_ms(5);
llagendijk 0:9e72c57b16fd 66 // 5. Send 0x2 and wait 200 ms (should go to 4-bit mode now)
llagendijk 0:9e72c57b16fd 67 writeHalfByte(0x2);
llagendijk 0:9e72c57b16fd 68 wait_ms(5);
llagendijk 0:9e72c57b16fd 69 // 7. Send LCD setup sequence (eg 0x2, 0x8 (=0x28), 0x0, 0x8 (=0x08), etc.)
llagendijk 0:9e72c57b16fd 70 writeCommand(0x28); // Function set 001 BW N F - -
llagendijk 0:9e72c57b16fd 71 wait_ms(15);
llagendijk 0:9e72c57b16fd 72
llagendijk 0:9e72c57b16fd 73 writeCommand(0x08); // display off, cursor invisible
llagendijk 0:9e72c57b16fd 74 wait_ms(15);
llagendijk 0:9e72c57b16fd 75
llagendijk 0:9e72c57b16fd 76 writeCommand(0x01);
llagendijk 0:9e72c57b16fd 77 wait_ms(15); // 1.64ms command
llagendijk 0:9e72c57b16fd 78
llagendijk 0:9e72c57b16fd 79 writeCommand(0x0C); // display enabled, cursor invisible
llagendijk 0:9e72c57b16fd 80 wait_ms(15);
llagendijk 0:9e72c57b16fd 81
llagendijk 0:9e72c57b16fd 82 writeCommand(0x6); // Cursor Direction and Display Shift : 0000 01 CD S (CD 0-left, 1-right S(hift) 0-no, 1-yes
llagendijk 0:9e72c57b16fd 83 wait_ms(15);
llagendijk 0:9e72c57b16fd 84
llagendijk 0:9e72c57b16fd 85 locate(0,0);
llagendijk 0:9e72c57b16fd 86 }
llagendijk 0:9e72c57b16fd 87
llagendijk 0:9e72c57b16fd 88 // memory starts at 0x80, and is 0x40 chars long per row
llagendijk 0:9e72c57b16fd 89 // However, rows 2 and 3 of 4-line displays are actually adjacent to rows 0 and 1.
llagendijk 0:9e72c57b16fd 90 // 16x4 displays are addressed the same way as 20x4 ones.
llagendijk 0:9e72c57b16fd 91
llagendijk 0:9e72c57b16fd 92 void TextLCD::character(uint16_t column, uint16_t row, int c) {
llagendijk 0:9e72c57b16fd 93 int address;
llagendijk 0:9e72c57b16fd 94 address = 0x80 + ((row & ~2) * 0x40) + column;
llagendijk 0:9e72c57b16fd 95 if (row > 1)
llagendijk 0:9e72c57b16fd 96 address += 20;
llagendijk 0:9e72c57b16fd 97 writeCommand(address);
llagendijk 0:9e72c57b16fd 98 writeData(c);
llagendijk 0:9e72c57b16fd 99 }
llagendijk 0:9e72c57b16fd 100
llagendijk 0:9e72c57b16fd 101 void TextLCD::writeHalfByte(uint16_t value) {
llagendijk 0:9e72c57b16fd 102 _e = 1;
llagendijk 0:9e72c57b16fd 103 wait_us(1);
llagendijk 0:9e72c57b16fd 104 _d = value & 0x0F; // send data on bus
llagendijk 0:9e72c57b16fd 105 wait_us(1); // setup time
llagendijk 0:9e72c57b16fd 106 _e = 0; // strobe
llagendijk 0:9e72c57b16fd 107 wait_us(1); // hold time
llagendijk 0:9e72c57b16fd 108 }
llagendijk 0:9e72c57b16fd 109
llagendijk 0:9e72c57b16fd 110 void TextLCD::writeByte(uint16_t value) {
llagendijk 0:9e72c57b16fd 111 writeHalfByte(value>>4);
llagendijk 0:9e72c57b16fd 112 writeHalfByte(value);
llagendijk 0:9e72c57b16fd 113 }
llagendijk 0:9e72c57b16fd 114
llagendijk 0:9e72c57b16fd 115 void TextLCD::writeCommand(uint16_t command) {
llagendijk 0:9e72c57b16fd 116 _rs = 0;
llagendijk 0:9e72c57b16fd 117 writeByte(command);
llagendijk 0:9e72c57b16fd 118 waitUntilDone();
llagendijk 0:9e72c57b16fd 119 }
llagendijk 0:9e72c57b16fd 120
llagendijk 0:9e72c57b16fd 121 void TextLCD::writeData(uint16_t data) {
llagendijk 0:9e72c57b16fd 122 _rs = 1;
llagendijk 0:9e72c57b16fd 123 writeByte(data);
llagendijk 0:9e72c57b16fd 124 waitUntilDone();
llagendijk 0:9e72c57b16fd 125 }
llagendijk 0:9e72c57b16fd 126
llagendijk 0:9e72c57b16fd 127 void TextLCD::cls() {
llagendijk 0:9e72c57b16fd 128 writeCommand(0x01);
llagendijk 0:9e72c57b16fd 129 wait_us(2000); // 1.64ms command
llagendijk 0:9e72c57b16fd 130 locate(0,0);
llagendijk 0:9e72c57b16fd 131 }
llagendijk 0:9e72c57b16fd 132
llagendijk 0:9e72c57b16fd 133 // This should be changed to use readAddressAndBusy() when that works.
llagendijk 0:9e72c57b16fd 134 void TextLCD::waitUntilDone() {
llagendijk 0:9e72c57b16fd 135 wait_us(60);
llagendijk 0:9e72c57b16fd 136 }
llagendijk 0:9e72c57b16fd 137
llagendijk 0:9e72c57b16fd 138 // Return the busy/address byte.
llagendijk 0:9e72c57b16fd 139 // The busy flag is the high bit.
llagendijk 0:9e72c57b16fd 140 // Not yet working reliably.
llagendijk 0:9e72c57b16fd 141 uint16_t TextLCD::readAddressAndBusy() {
llagendijk 0:9e72c57b16fd 142 _d.input();
llagendijk 0:9e72c57b16fd 143 _rw = 1;
llagendijk 0:9e72c57b16fd 144 wait_us(1);
llagendijk 0:9e72c57b16fd 145 _e = 1;
llagendijk 0:9e72c57b16fd 146 wait_us(1);
llagendijk 0:9e72c57b16fd 147 _e = 0;
llagendijk 0:9e72c57b16fd 148
llagendijk 0:9e72c57b16fd 149 uint16_t retval = _d.read() << 4;
llagendijk 0:9e72c57b16fd 150
llagendijk 0:9e72c57b16fd 151 wait_us(1);
llagendijk 0:9e72c57b16fd 152 _e = 1;
llagendijk 0:9e72c57b16fd 153 wait_us(1);
llagendijk 0:9e72c57b16fd 154 _e = 0;
llagendijk 0:9e72c57b16fd 155
llagendijk 0:9e72c57b16fd 156 retval |= _d.read();
llagendijk 0:9e72c57b16fd 157 _rw = 0;
llagendijk 0:9e72c57b16fd 158
llagendijk 0:9e72c57b16fd 159 _d.output();
llagendijk 0:9e72c57b16fd 160 return retval;
llagendijk 0:9e72c57b16fd 161 }
llagendijk 0:9e72c57b16fd 162