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
- Committer:
- jimherd
- Date:
- 2010-11-28
- Revision:
- 0:e5b7c70254ac
- Child:
- 7:020722c18a8b
File content as of revision 0:e5b7c70254ac:
/* draft mbed TextLCD * (c) 2007/8, sford * Modified jherd */ #include "WattBob_TextLCD.h" #include "MCP23017.h" #include "mbed.h" /* * Initialisation * ============== * * After attaching the supply voltage/after a reset, the display needs to be brought in to a defined state * * - wait approximately 15 ms so the display is ready to execute commands * - Execute the command 0x30 ("Display Settings") three times (wait 1,64ms after each command, the busy flag cannot be queried now). * - 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. * - If you want to use the 4 bit mode, now you can execute the command to switch over to this mode now. * - Execute the "clear display" command * * Timing * ====== * * Nearly all commands transmitted to the display need 40us for execution. * Exceptions are the commands "Clear Display and Reset" and "Set Cursor to Start Position" * These commands need 1.64ms for execution. These timings are valid for all displays working with an * internal clock of 250kHz. But I do not know any displays that use other frequencies. Any time you * can use the busy flag to test if the display is ready to accept the next command. * * _e is kept high apart from calling clock * _rw is kept 0 (write) apart from actions that uses it differently * _rs is set by the data/command writes * * RS = 7 * RW = 6 * E = 5 * Back light = 4 * D4 = 0 * D5 = 1 * D6 = 2 * D7 = 3 */ WattBob_TextLCD::WattBob_TextLCD(MCP23017 *port) { // // Initialise pointer to MCP23017 object // par_port = port; par_port->config(0x0F00, 0x0F00, 0x0F00); _rows = 2; _columns = 16; _rw(0); _e(0); _rs(0); // command mode // Should theoretically wait 15ms, but most things will be powered up pre-reset // so i'll disable that for the minute. If implemented, could wait 15ms post reset // instead // wait(0.015); // send "Display Settings" 3 times (Only top nibble of 0x30 as we've got 4-bit bus) for(int i=0; i<3; i++) { writeNibble(0x3); wait(0.00164); // this command takes 1.64ms, so wait for it } writeNibble(0x2); // 4-bit mode writeCommand(0x28); // Function set 001 BW N F - - writeCommand(0x0C); writeCommand(0x6); // Cursor Direction and Display Shift : 0000 01 CD S (CD 0-left, 1-right S(hift) 0-no, 1-yes cls(); } int WattBob_TextLCD::_putc(int value) { if(value == '\n') { newline(); } else { writeData(value); } return value; } int WattBob_TextLCD::_getc() { return 0; } void WattBob_TextLCD::newline() { _column = 0; _row++; if(_row >= _rows) { _row = 0; } locate(_column, _row); } void WattBob_TextLCD::locate(int row, int column) { if(column < 0 || column >= _columns || row < 0 || row >= _rows) { // error("locate(%d,%d) out of range on %dx%d display", column, row, _columns, _rows); return; } _row = row; _column = column; int address = 0x80 + (_row * 40) + _column; // memory starts at 0x80, and is 40 chars long per row writeCommand(address); } void WattBob_TextLCD::cls() { writeCommand(0x01); // Clear Display wait(0.00164f); // This command takes 1.64 ms locate(0, 0); } void WattBob_TextLCD::reset() { cls(); } void WattBob_TextLCD::clock() { wait(0.000040f); _e(1); wait(0.000040f); // most instructions take 40us _e(0); } void WattBob_TextLCD::writeNibble(int value) { _d(value); clock(); } void WattBob_TextLCD::writeByte(int value) { writeNibble((value >> 4) & 0x000F); writeNibble((value >> 0) & 0x000F); } void WattBob_TextLCD::writeCommand(int command) { _rs(0); writeByte(command); } void WattBob_TextLCD::writeData(int data) { _rs(1); writeByte(data); _column++; if(_column >= _columns) { newline(); } } void WattBob_TextLCD::_rs(int data) { par_port->write_bit(data, RS_BIT); } void WattBob_TextLCD::_rw(int data) { par_port->write_bit(data, RW_BIT); } void WattBob_TextLCD::_e(int data) { par_port->write_bit(data, E_BIT); } void WattBob_TextLCD::_d(int data) { par_port->write_mask((unsigned short)data, (unsigned short)0x000F); }