Hello, Massimo;
Since you've made LiquidCrystal part of standard libraries beginning with 0012 - I have a suggestion:
LiquidCrystal can use 4 or 8 bit mode;
and will utilize the following LCD module pins:
4 bit: RW, EN, RS, D4, D5, D6, D7
8 bit: RW, EN, RS, D0, D1, D4, D3, D4, D5, D6, D7
However, in many cases there is no need to use 7/11 pins for 4/8 bit LCD control mode; instead, RW pin of LCD can be hard wired to GND, to save 1 Arduino pin for purposes other then LCD; thus LCD will consume 6/10 pins total.
I propose to use "-1" value for RW in LiquidCrystal constructor to tell this library to ignore / do not use this pin.
Proposed code comes below;
Cheers.
++++++++++++++++++++++++++++++
#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).
// set rw = -1, if pin should not be used by arduino
// in this case hard wire rw pin of LCD module to GND.
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(_enable_pin, OUTPUT);
pinMode(_rs_pin, OUTPUT);
if (_rw_pin >= 0) { // "do not use rw" indicated by rw = -1
pinMode(_rw_pin, OUTPUT);
}
for (int i = 0; i < 8; i++)
pinMode(_data_pins*, OUTPUT);*
- 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(_enable_pin, OUTPUT);*
- pinMode(_rs_pin, OUTPUT);*
- if (_rw_pin >= 0) { // "do not use rw" indicated by rw = -1*
- pinMode(_rw_pin, OUTPUT);*
- }*
- for (int i = 0; i < 4; i++)*
pinMode(data_pins*, OUTPUT);
_ 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);
if (rw_pin >= 0) { // "do not use rw" indicated by rw = -1*
* digitalWrite(rw_pin, LOW);
_ }*
* if (four_bit_mode) {
_ for (int i = 0; i < 4; i++) {*
digitalWrite(data_pins*, (value >> (i + 4)) & 0x01);*
* }*
* digitalWrite(enable_pin, HIGH);
digitalWrite(enable_pin, LOW);*
* for (int i = 0; i < 4; i++) {*
digitalWrite(data_pins*, (value >> i) & 0x01);*
* }*
* digitalWrite(enable_pin, HIGH);
digitalWrite(enable_pin, LOW);*
* } else {*
* for (int i = 0; i < 8; i++) {*
digitalWrite(data_pins*, (value >> i) & 0x01);*
* }_
digitalWrite(enable_pin, HIGH);
digitalWrite(enable_pin, LOW);*
* }*
}
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