Ok, I've had a look at LiquidCrystal and modified the timing according to my own code. However, in order to use the same init sequence in four-bit-mode, I need to re-structure the send-method a bit and I don't have time for that tonight.
Btw does anybody use 8-bit-mode with this library? I really don't see any reason for using this when the four-bit-mode is already there. Removing 8-bit-support will save a few bytes and simplify the code.
scootabug: You can try this modified version of LiquidCrystal.cpp, but I don't think it will make much difference in your case as I haven't modified the init-sequence yet. It's possible that the extended enable-pulse and delays between writes will help though, so please try it.
LiquidCrystal.cpp:
#include "LiquidCrystal.h"
#include <stdio.h>
#include <string.h>
#include <inttypes.h>
#include "WProgram.h"
// When the display powers up, it is configured as follows:
//
// 1. Display clear
// 2. Function set:
// DL = 1; 8-bit interface data
// N = 0; 1-line display
// F = 0; 5x8 dot character font
// 3. Display on/off control:
// D = 0; Display off
// C = 0; Cursor off
// B = 0; Blinking off
// 4. Entry mode set:
// I/D = 1; Increment by 1
// S = 0; No shift
//
// Note, however, that resetting the Arduino doesn't reset the LCD, so we
// can't assume that its in that state when a sketch starts (and the
// LiquidCrystal constructor is called).
LiquidCrystal::LiquidCrystal(uint8_t rs, uint8_t rw, uint8_t enable,
uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3,
uint8_t d4, uint8_t d5, uint8_t d6, uint8_t d7) :
_four_bit_mode(0), _rs_pin(rs), _rw_pin(rw), _enable_pin(enable)
{
_data_pins[0] = d0;
_data_pins[1] = d1;
_data_pins[2] = d2;
_data_pins[3] = d3;
_data_pins[4] = d4;
_data_pins[5] = d5;
_data_pins[6] = d6;
_data_pins[7] = d7;
pinMode(_rs_pin, OUTPUT);
if (_rw_pin != NO_RW)
pinMode(_rw_pin, OUTPUT);
pinMode(_enable_pin, OUTPUT);
for (int i = 0; i < 8; i++)
pinMode(_data_pins[i], OUTPUT);
delay(16); // The LCD must be powered on for at least 15ms before init
command(0x38); // function set: 8 bits, 1 line, 5x8 dots
command(0x0C); // display control: turn display on, cursor off, no blinking
command(0x06); // entry mode set: increment automatically, display shift, right shift
clear();
}
LiquidCrystal::LiquidCrystal(uint8_t rs, uint8_t rw, uint8_t enable,
uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3) :
_four_bit_mode(1), _rs_pin(rs), _rw_pin(rw), _enable_pin(enable)
{
_data_pins[0] = d0;
_data_pins[1] = d1;
_data_pins[2] = d2;
_data_pins[3] = d3;
pinMode(_rs_pin, OUTPUT);
pinMode(_rw_pin, OUTPUT);
pinMode(_enable_pin, OUTPUT);
for (int i = 0; i < 4; i++)
pinMode(_data_pins[i], OUTPUT);
delay(16); // The LCD must be powered on for at least 15ms before init
command(0x28); // function set: 4 bits, 1 line, 5x8 dots
command(0x0C); // display control: turn display on, cursor off, no blinking
command(0x06); // entry mode set: increment automatically, display shift, right shift
clear();
}
void LiquidCrystal::clear()
{
command(0x01); // clear display, set cursor position to zero
delayMicroseconds(2000);
}
void LiquidCrystal::home()
{
command(0x02); // set cursor position to zero
delayMicroseconds(2000);
}
void LiquidCrystal::setCursor(int col, int row)
{
int row_offsets[] = { 0x00, 0x40, 0x14, 0x54 };
command(0x80 | (col + row_offsets[row]));
}
void LiquidCrystal::command(uint8_t value) {
send(value, LOW);
}
void LiquidCrystal::write(uint8_t value) {
send(value, HIGH);
}
void LiquidCrystal::send(uint8_t value, uint8_t mode) {
digitalWrite(_rs_pin, mode);
digitalWrite(_rw_pin, LOW);
if (_four_bit_mode) {
for (int i = 0; i < 4; i++) {
digitalWrite(_data_pins[i], (value >> (i + 4)) & 0x01);
}
digitalWrite(_enable_pin, HIGH);
delayMicroseconds(1);
digitalWrite(_enable_pin, LOW);
for (int i = 0; i < 4; i++) {
digitalWrite(_data_pins[i], (value >> i) & 0x01);
}
digitalWrite(_enable_pin, HIGH);
delayMicroseconds(1);
digitalWrite(_enable_pin, LOW);
} else {
for (int i = 0; i < 8; i++) {
digitalWrite(_data_pins[i], (value >> i) & 0x01);
}
digitalWrite(_enable_pin, HIGH);
delayMicroseconds(1);
digitalWrite(_enable_pin, LOW);
}
delayMicroseconds(45);
}