Set of routines to access 16*32character LCD display on WattBob I board.
Dependents: Assignment_2_herpe Final_V1 ass2 ass2 ... more
Diff: WattBob_TextLCD.cpp
- Revision:
- 0:e5b7c70254ac
- Child:
- 7:020722c18a8b
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/WattBob_TextLCD.cpp Sun Nov 28 22:47:51 2010 +0000 @@ -0,0 +1,167 @@ +/* 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); +}