/Users/fmalpartida/Documents/development/mercurial repos/SW/NewLiquidCrystal_lib/LiquidCrystal_SR2W.h
// ---------------------------------------------------------------------------
// Created/Adapted by Bill Perry 2012-03-16
// Copyright (C) - 2018
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License v3.0
// along with this program.
// If not, see <https://www.gnu.org/licenses/gpl-3.0.en.html>.
//
// ---------------------------------------------------------------------------
//
// @file LiquidCrystal_SR2W.h
// Connects a hd44780 LCD using 2 pins from the Arduino, via an 8-bit
// ShiftRegister (SR2W from now on).
//
// @brief
// This is the 2 wire shift register interface class for the LCD library
//
// The functionality provided by this class and its base class is a superset of
// the original functionality of the Arduino LiquidCrystal library and can
// be used as such.
// See the LCD class for a full description of the API functions available.
//
// It works with a 8-bit unlatched, no-tristate, unidirectional SIPO (Serial-In-Parallel-Out)
// shift register (IE a very simple SR), and an hd44780 LCD in 4-bit mode.
// Any such shift register should do (pref. 74LS family IC's for 2-wire).
// 74LS164 and 74HC595 have been exstensively tested.
//
//
// 2 Pins required from the Arduino:
// - Data/Enable
// - Clock
// The Data pin is also used to control the enable signal
// LCD RW-pin hardwired to LOW (only writing to LCD).
// Busy Flag (BF, data bit D7) is not read.
//
// Original project homepage: http://code.google.com/p/arduinoshiftreglcd/
//
// Shift register bits
// Bit #0 - (cannot be used on 74HC595)
// Bit #1 - optional backlight control
// Bit #2 - connects to RS (Register Select) on the LCD
// Bit #3 - connects to LCD data inputs D4
// Bit #4 - connects to LCD data inputs D5
// Bit #5 - connects to LCD data inputs D6
// Bit #6 - connects to LCD data inputs D7
// Bit #7 - enables the LCD enable-puls (via the diode-resistor AND "gate")
//
// Wiring for a 74LS164
// ---------------------
// 1k/4.7k
// +--------[ Resistor ]--------+---(LCD Enable)
// | |
// | 74LS164 (VCC) |
// | +----u----+ | _V_ diode
// (data pin)---+---+--1-|A VCC|-14-+ |
// | | | |
// +--2-|B Q7|-13------+
// 3-|Q0 Q6|-12--(LCD D7)
// (BL Circuit)--------4-|Q1 Q5|-11--(LCD D6)
// (LCD RS)------------5-|Q2 Q4|-10--(LCD D5)
// (LCD D4)------------6-|Q3 /MR|--9--(VCC)
// +-7-|GND CP|--8--(clock pin)
// | +---------+
// | 0.1uf
// (gnd)-----||----(vcc)
//
// Wiring for a 74HC595
// --------------------
// NOTE: the 74HC595 is a latching shift register. In order to get it to operate
// in a "non latching" mode, RCLK and SCLK are tied together. The side effect of this
// is that the latched output is one clock behind behind the internal shift register bits.
// To compensate for this the wiring is offset by one bit position lower.
// For example, while the backlight is hooked to Q0 it is still using bit 1 of
// of the shift register because the outputs are 1 clock behind the real internal shift
// register.
//
// 74HC595 (VCC)
// +----u----+ | +-----------------------(BL circuit)
// (LCD RS)------------1-|Q1 VCC|-16-+ | +--------------------(data pin)
// (LCD D4)------------2-|Q2 Q0|-15----+ | 1k/4.7k
// (LCD D5)------------3-|Q3 SER|-14-------+---[ Resistor ]--+--(LCD Enable)
// (LCD D6)------------4-|Q4 /OE|-13--(gnd) |
// (LCD D7)------------5-|Q5 RCLK|-12-------+ |
// | | | |
// +------6-|Q6 SCLK|-11-------+--(clock pin) |
// | 7-|Q7 /MR|-10--(VCC) |
// | +-8-|GND Q6'|--9 |
// | | +---------+ diode _V_
// | | 0.1uf |
// | (gnd)-----||----(vcc) |
// +-----------------------------------------------+
//
//
// Backlight Control circuit
// -------------------------
// Because the shift resiter is not latching the outputs, the backlight circuitry
// will "see" the output bits as they are shifted into the shift register which
// can cause the backlight to flicker rather than remain constantly on/off.
// The circuit below slows down the transitions to the transistor to remove
// the visible flicker. When the BL input is HIGH the LCD backlight will turn on.
//
// (value depends on LCD, 100ohm is usually safe)
// (LCD BL anode)---[ resistor ]---(vcc)
//
// (LCD BL cathode)-------------------------------+
// |
// D
// |
// (BL input)----[ 4.7k Resistor ]----+-------G-|-< (2N7000 FET)
// | |
// (0.1uf) = S
// | |
// (gnd) (gnd)
//
//
//
//
// History
// 2012.03.16 bperrybap - creation/adaption from SR header to create SR2W header.
// Fixed typo in SR2W mask define names
// @author B. Perry - bperrybap@opensource.billsworld.billandterrie.com
// --------------------------------------------------------------------------------
#ifndef _LIQUIDCRYSTAL_SR2W_
#define _LIQUIDCRYSTAL_SR2W_
#include <inttypes.h>
#include "LCD.h"
#include "FastIO.h"
// two-wire SR output bit constants
// ---------------------------------------------------------------------------
#define SR2W_BL_MASK 0x02
#define SR2W_RS_MASK 0x04
#define SR2W_DATA_MASK 0x78 // data bits are hard coded to be SR bits 6,5,4,3
#define SR2W_EN_MASK 0x80 // cannot ever be changed
class LiquidCrystal_SR2W : public LCD
{
public:
LiquidCrystal_SR2W (uint8_t srdata, uint8_t srclock, t_backlightPol blpol = POSITIVE);
virtual void send(uint8_t value, uint8_t mode);
void setBacklight ( uint8_t mode );
private:
void init ( uint8_t srdata, uint8_t srclock, t_backlightPol blpol, uint8_t lines, uint8_t font );
void loadSR (uint8_t val);
fio_register _srDataRegister; // Serial Data pin
fio_bit _srDataMask;
fio_register _srClockRegister; // Clock Pin
fio_bit _srClockMask;
uint8_t _blPolarity;
uint8_t _blMask;
};
#endif
LiquidCrystal_SR2W::setBacklight
void setBacklight(uint8_t mode)
Definition: LiquidCrystal_SR2W.cpp:129
LiquidCrystal_SR2W
Definition: LiquidCrystal_SR2W.h:149
LiquidCrystal_SR2W::LiquidCrystal_SR2W
LiquidCrystal_SR2W(uint8_t srdata, uint8_t srclock, t_backlightPol blpol=POSITIVE)
Definition: LiquidCrystal_SR2W.cpp:49
LCD
Definition: LCD.h:199
LiquidCrystal_SR2W::send
virtual void send(uint8_t value, uint8_t mode)
Definition: LiquidCrystal_SR2W.cpp:102