jim herd / WattBob_TextLCD

Set of routines to access 16*32character LCD display on WattBob I board.

Dependents:   Assignment_2_herpe Final_V1 ass2 ass2 ... more

WattBob_TextLCD.cpp@7:020722c18a8b, 2011-03-24 (annotated)

Committer:
jimherd
Date:
Thu Mar 24 13:46:06 2011 +0000
Revision:
7:020722c18a8b
Parent:
0:e5b7c70254ac
Child:
8:5a1c4254e4a6
Fixed bug in \locate\ function

Who changed what in which revision?

UserRevisionLine numberNew contents of line
jimherd 0:e5b7c70254ac 1 /* draft mbed TextLCD
jimherd 0:e5b7c70254ac 2 * (c) 2007/8, sford
jimherd 0:e5b7c70254ac 3 * Modified jherd
jimherd 0:e5b7c70254ac 4 */
jimherd 0:e5b7c70254ac 5
jimherd 0:e5b7c70254ac 6 #include "WattBob_TextLCD.h"
jimherd 0:e5b7c70254ac 7 #include "MCP23017.h"
jimherd 0:e5b7c70254ac 8
jimherd 0:e5b7c70254ac 9 #include "mbed.h"
jimherd 0:e5b7c70254ac 10
jimherd 0:e5b7c70254ac 11 /*
jimherd 0:e5b7c70254ac 12 * Initialisation
jimherd 0:e5b7c70254ac 13 * ==============
jimherd 0:e5b7c70254ac 14 *
jimherd 0:e5b7c70254ac 15 * After attaching the supply voltage/after a reset, the display needs to be brought in to a defined state
jimherd 0:e5b7c70254ac 16 *
jimherd 0:e5b7c70254ac 17 * - wait approximately 15 ms so the display is ready to execute commands
jimherd 0:e5b7c70254ac 18 * - Execute the command 0x30 ("Display Settings") three times (wait 1,64ms after each command, the busy flag cannot be queried now).
jimherd 0:e5b7c70254ac 19 * - 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.
jimherd 0:e5b7c70254ac 20 * - If you want to use the 4 bit mode, now you can execute the command to switch over to this mode now.
jimherd 0:e5b7c70254ac 21 * - Execute the "clear display" command
jimherd 0:e5b7c70254ac 22 *
jimherd 0:e5b7c70254ac 23 * Timing
jimherd 0:e5b7c70254ac 24 * ======
jimherd 0:e5b7c70254ac 25 *
jimherd 0:e5b7c70254ac 26 * Nearly all commands transmitted to the display need 40us for execution.
jimherd 0:e5b7c70254ac 27 * Exceptions are the commands "Clear Display and Reset" and "Set Cursor to Start Position"
jimherd 0:e5b7c70254ac 28 * These commands need 1.64ms for execution. These timings are valid for all displays working with an
jimherd 0:e5b7c70254ac 29 * internal clock of 250kHz. But I do not know any displays that use other frequencies. Any time you
jimherd 0:e5b7c70254ac 30 * can use the busy flag to test if the display is ready to accept the next command.
jimherd 0:e5b7c70254ac 31 *
jimherd 0:e5b7c70254ac 32 * _e is kept high apart from calling clock
jimherd 0:e5b7c70254ac 33 * _rw is kept 0 (write) apart from actions that uses it differently
jimherd 0:e5b7c70254ac 34 * _rs is set by the data/command writes
jimherd 0:e5b7c70254ac 35 *
jimherd 0:e5b7c70254ac 36 * RS = 7
jimherd 0:e5b7c70254ac 37 * RW = 6
jimherd 0:e5b7c70254ac 38 * E = 5
jimherd 0:e5b7c70254ac 39 * Back light = 4
jimherd 0:e5b7c70254ac 40 * D4 = 0
jimherd 0:e5b7c70254ac 41 * D5 = 1
jimherd 0:e5b7c70254ac 42 * D6 = 2
jimherd 0:e5b7c70254ac 43 * D7 = 3
jimherd 0:e5b7c70254ac 44 */
jimherd 0:e5b7c70254ac 45
jimherd 0:e5b7c70254ac 46 WattBob_TextLCD::WattBob_TextLCD(MCP23017 *port) {
jimherd 0:e5b7c70254ac 47 //
jimherd 0:e5b7c70254ac 48 // Initialise pointer to MCP23017 object
jimherd 0:e5b7c70254ac 49 //
jimherd 0:e5b7c70254ac 50 par_port = port;
jimherd 0:e5b7c70254ac 51 par_port->config(0x0F00, 0x0F00, 0x0F00);
jimherd 0:e5b7c70254ac 52
jimherd 0:e5b7c70254ac 53 _rows = 2;
jimherd 0:e5b7c70254ac 54 _columns = 16;
jimherd 0:e5b7c70254ac 55
jimherd 0:e5b7c70254ac 56 _rw(0);
jimherd 0:e5b7c70254ac 57 _e(0);
jimherd 0:e5b7c70254ac 58 _rs(0); // command mode
jimherd 0:e5b7c70254ac 59
jimherd 0:e5b7c70254ac 60 // Should theoretically wait 15ms, but most things will be powered up pre-reset
jimherd 0:e5b7c70254ac 61 // so i'll disable that for the minute. If implemented, could wait 15ms post reset
jimherd 0:e5b7c70254ac 62 // instead
jimherd 0:e5b7c70254ac 63 // wait(0.015);
jimherd 0:e5b7c70254ac 64
jimherd 0:e5b7c70254ac 65 // send "Display Settings" 3 times (Only top nibble of 0x30 as we've got 4-bit bus)
jimherd 0:e5b7c70254ac 66 for(int i=0; i<3; i++) {
jimherd 0:e5b7c70254ac 67 writeNibble(0x3);
jimherd 0:e5b7c70254ac 68 wait(0.00164); // this command takes 1.64ms, so wait for it
jimherd 0:e5b7c70254ac 69 }
jimherd 0:e5b7c70254ac 70 writeNibble(0x2); // 4-bit mode
jimherd 0:e5b7c70254ac 71 writeCommand(0x28); // Function set 001 BW N F - -
jimherd 0:e5b7c70254ac 72 writeCommand(0x0C);
jimherd 0:e5b7c70254ac 73 writeCommand(0x6); // Cursor Direction and Display Shift : 0000 01 CD S (CD 0-left, 1-right S(hift) 0-no, 1-yes
jimherd 0:e5b7c70254ac 74
jimherd 0:e5b7c70254ac 75 cls();
jimherd 0:e5b7c70254ac 76 }
jimherd 0:e5b7c70254ac 77
jimherd 0:e5b7c70254ac 78 int WattBob_TextLCD::_putc(int value) {
jimherd 0:e5b7c70254ac 79 if(value == '\n') {
jimherd 0:e5b7c70254ac 80 newline();
jimherd 0:e5b7c70254ac 81 } else {
jimherd 0:e5b7c70254ac 82 writeData(value);
jimherd 0:e5b7c70254ac 83 }
jimherd 0:e5b7c70254ac 84 return value;
jimherd 0:e5b7c70254ac 85 }
jimherd 0:e5b7c70254ac 86
jimherd 0:e5b7c70254ac 87 int WattBob_TextLCD::_getc() {
jimherd 0:e5b7c70254ac 88 return 0;
jimherd 0:e5b7c70254ac 89 }
jimherd 0:e5b7c70254ac 90
jimherd 0:e5b7c70254ac 91 void WattBob_TextLCD::newline() {
jimherd 0:e5b7c70254ac 92 _column = 0;
jimherd 0:e5b7c70254ac 93 _row++;
jimherd 0:e5b7c70254ac 94 if(_row >= _rows) {
jimherd 0:e5b7c70254ac 95 _row = 0;
jimherd 0:e5b7c70254ac 96 }
jimherd 0:e5b7c70254ac 97 locate(_column, _row);
jimherd 0:e5b7c70254ac 98 }
jimherd 0:e5b7c70254ac 99
jimherd 0:e5b7c70254ac 100 void WattBob_TextLCD::locate(int row, int column) {
jimherd 0:e5b7c70254ac 101 if(column < 0 || column >= _columns || row < 0 || row >= _rows) {
jimherd 0:e5b7c70254ac 102 // error("locate(%d,%d) out of range on %dx%d display", column, row, _columns, _rows);
jimherd 0:e5b7c70254ac 103 return;
jimherd 0:e5b7c70254ac 104 }
jimherd 0:e5b7c70254ac 105
jimherd 0:e5b7c70254ac 106 _row = row;
jimherd 0:e5b7c70254ac 107 _column = column;
jimherd 7:020722c18a8b 108 int address = 0x80 + (_row * 0x40) + _column; // memory starts at 0x80, and internally it is 40 chars per row (only first 16 used)
jimherd 0:e5b7c70254ac 109 writeCommand(address);
jimherd 0:e5b7c70254ac 110 }
jimherd 0:e5b7c70254ac 111
jimherd 0:e5b7c70254ac 112 void WattBob_TextLCD::cls() {
jimherd 0:e5b7c70254ac 113 writeCommand(0x01); // Clear Display
jimherd 0:e5b7c70254ac 114 wait(0.00164f); // This command takes 1.64 ms
jimherd 0:e5b7c70254ac 115 locate(0, 0);
jimherd 0:e5b7c70254ac 116 }
jimherd 0:e5b7c70254ac 117
jimherd 0:e5b7c70254ac 118 void WattBob_TextLCD::reset() {
jimherd 0:e5b7c70254ac 119 cls();
jimherd 0:e5b7c70254ac 120 }
jimherd 0:e5b7c70254ac 121
jimherd 0:e5b7c70254ac 122 void WattBob_TextLCD::clock() {
jimherd 0:e5b7c70254ac 123 wait(0.000040f);
jimherd 0:e5b7c70254ac 124 _e(1);
jimherd 0:e5b7c70254ac 125 wait(0.000040f); // most instructions take 40us
jimherd 0:e5b7c70254ac 126 _e(0);
jimherd 0:e5b7c70254ac 127 }
jimherd 0:e5b7c70254ac 128
jimherd 0:e5b7c70254ac 129 void WattBob_TextLCD::writeNibble(int value) {
jimherd 0:e5b7c70254ac 130 _d(value);
jimherd 0:e5b7c70254ac 131 clock();
jimherd 0:e5b7c70254ac 132 }
jimherd 0:e5b7c70254ac 133
jimherd 0:e5b7c70254ac 134 void WattBob_TextLCD::writeByte(int value) {
jimherd 0:e5b7c70254ac 135 writeNibble((value >> 4) & 0x000F);
jimherd 0:e5b7c70254ac 136 writeNibble((value >> 0) & 0x000F);
jimherd 0:e5b7c70254ac 137 }
jimherd 0:e5b7c70254ac 138
jimherd 0:e5b7c70254ac 139 void WattBob_TextLCD::writeCommand(int command) {
jimherd 0:e5b7c70254ac 140 _rs(0);
jimherd 0:e5b7c70254ac 141 writeByte(command);
jimherd 0:e5b7c70254ac 142 }
jimherd 0:e5b7c70254ac 143
jimherd 0:e5b7c70254ac 144 void WattBob_TextLCD::writeData(int data) {
jimherd 0:e5b7c70254ac 145 _rs(1);
jimherd 0:e5b7c70254ac 146 writeByte(data);
jimherd 0:e5b7c70254ac 147 _column++;
jimherd 0:e5b7c70254ac 148 if(_column >= _columns) {
jimherd 0:e5b7c70254ac 149 newline();
jimherd 0:e5b7c70254ac 150 }
jimherd 0:e5b7c70254ac 151 }
jimherd 0:e5b7c70254ac 152
jimherd 0:e5b7c70254ac 153 void WattBob_TextLCD::_rs(int data) {
jimherd 0:e5b7c70254ac 154 par_port->write_bit(data, RS_BIT);
jimherd 0:e5b7c70254ac 155 }
jimherd 0:e5b7c70254ac 156
jimherd 0:e5b7c70254ac 157 void WattBob_TextLCD::_rw(int data) {
jimherd 0:e5b7c70254ac 158 par_port->write_bit(data, RW_BIT);
jimherd 0:e5b7c70254ac 159 }
jimherd 0:e5b7c70254ac 160
jimherd 0:e5b7c70254ac 161 void WattBob_TextLCD::_e(int data) {
jimherd 0:e5b7c70254ac 162 par_port->write_bit(data, E_BIT);
jimherd 0:e5b7c70254ac 163 }
jimherd 0:e5b7c70254ac 164
jimherd 0:e5b7c70254ac 165 void WattBob_TextLCD::_d(int data) {
jimherd 0:e5b7c70254ac 166 par_port->write_mask((unsigned short)data, (unsigned short)0x000F);
jimherd 0:e5b7c70254ac 167 }