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// ---------------------------------------------------------------------------
// Created by Francisco Malpartida on 20/08/11.
// Copyright 2011 - Under creative commons license 3.0:
// Attribution-ShareAlike CC BY-SA
// This software is furnished "as is", without technical support, and with no
// warranty, express or implied, as to its usefulness for any purpose.
// Thread Safe: No
// Extendable: Yes
// @file LiquidCrystal_SR.h
// Connects an LCD using 2 or 3 pins from the Arduino, via an 8-bit
// ShiftRegister (SR from now on).
// @brief
// This is a port of the ShiftRegLCD library from raron and ported to the
// LCD library.
// The functionality provided by this class and its base class is identical
// to the original functionality of the Arduino LiquidCrystal library and can
// be used as such.
// Modified to work serially with the shiftOut() function, an 8-bit shiftregister
// (SR) and an LCD in 4-bit mode.
// Shiftregister connection description (NEW as of 2009.07.27)
// Bit #0 - N/C - not connected, used to hold a zero
// Bits #1 - N/C
// Bit #2 - connects to RS (Register Select) on the LCD
// Bits #3 - #6 from SR connects to LCD data inputs D4 - D7.
// Bit #7 - is used to enabling the enable-puls (via a diode-resistor AND "gate")
// 2 or 3 Pins required from the Arduino for Data, Clock, and Enable (optional).
// If not using Enable, the Data pin is used for the enable signal by defining
// the same pin for Enable as for Data. Data and Clock outputs/pins goes to the
// shiftregister.
// LCD RW-pin hardwired to LOW (only writing to LCD). Busy Flag (BF, data bit D7)
// is not read.
// Any shift register should do. I used 74LS164, for the reason that's what I
// had at hand.
// Original project homepage:
// History
// 2011.10.29 fmalpartida - adaption of the library to the LCD class hierarchy.
// 2009.05.23 raron - but; based mostly (as in almost verbatim) on the
// "official" LiquidCrystal library.
// 2009.07.23 Incorporated some proper initialization routines
// inspired (lets say copy-paste-tweaked) from LiquidCrystal library
// improvements from LadyAda
// 2009.07.25 raron - Fixed comments. I really messed up the comments before
// posting this, so I had to fix it.
// Also renamed a function, but no improvements or functional changes.
// 2009.07.27 Thanks to an excellent suggestion from mircho at the Arduiono
// playgrond forum, the number of wires now required is only two!
// 2009.07.28 Mircho / raron - a new modification to the schematics, and a more
// streamlined interface
// 2009.07.30 raron - minor corrections to the comments. Fixed keyword highlights.
// Fixed timing to datasheet safe.
// 2011.07.02 Fixed a minor flaw in setCursor function. No functional change,
// just a bit more memory efficient.
// Thanks to CapnBry (from google code and github) who noticed it.
// URL to his version of shiftregLCD:
// This library is only compatible with Arduino's SDK version 1.0
// @author F. Malpartida -
// ---------------------------------------------------------------------------
#include <inttypes.h>
#include <LCD.h>
// two-wire indicator constant
// ---------------------------------------------------------------------------
#define TWO_WIRE 204
#define SR_RS_BIT 0x04
#define SR_EN_BIT 0x80
class LiquidCrystal_SR : public LCD
@abstract LCD SHIFT REGISTER constructors.
@discussion Defines the pin assignment that the LCD will have.
The constructor does not initialize the LCD. Assuming 1 line 8 pixel high
@param srdata[in] pin for shiftregister data line.
@param srclock[in] pin for shiftregister clock line.
@param enable[in] enable pin for the shiftregister.
LiquidCrystal_SR ( uint8_t srdata, uint8_t srclock, uint8_t enable );
// Set nr. of lines, assume 8 pixel high font
LiquidCrystal_SR ( uint8_t srdata, uint8_t srclock, uint8_t enable,
uint8_t lines );
// Set nr. of lines and font
LiquidCrystal_SR( uint8_t srdata, uint8_t srclock, uint8_t enable,
uint8_t lines, uint8_t font );
@abstract LCD initialization.
@discussion Initializes the LCD to a given size (col, row). This methods
initializes the LCD, therefore, it MUST be called prior to using any other
method from this class or parent class.
@param cols[in] the number of columns that the display has
@param rows[in] the number of rows that the display has
@param charsize[in] size of the characters of the LCD: LCD_5x8DOTS or
virtual void begin(uint8_t cols, uint8_t rows, uint8_t charsize = LCD_5x8DOTS);
@abstract Send a particular value to the LCD.
@discussion Sends a particular value to the LCD for writing to the LCD or
as an LCD command using the shift register.
Users should never call this method.
@param value[in] Value to send to the LCD.
@result mode LOW - write to the LCD CGRAM, HIGH - write a command to
the LCD.
virtual void send(uint8_t value, uint8_t mode);
@abstract Initializes the LCD pin allocation
@discussion Initializes the LCD pin allocation and configuration.
void init ( uint8_t srdata, uint8_t srclock, uint8_t enable, uint8_t lines,
uint8_t font );
@abstract For sending data when initializing the display to 4-bit
@discussion Initializes the LCD pin allocation and configuration.
void write4bits ( uint8_t );
uint8_t _srdata_pin; // Serial Data pin
uint8_t _srclock_pin; // Clock Pin
uint8_t _enable_pin; // Enable Pin
uint8_t _two_wire; // two wire mode