1. F Malpartida
  2. New LiquidCrystal


New LiquidCrystal / LiquidCrystal_SR.h

// ---------------------------------------------------------------------------
// 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
// unlatched, no-tristate, unidirectional SIPO (Serial-In-Parallel-Out)
// shift register (IE a very simple SR), and an LCD in 4-bit mode.
// Any such shift register should do (pref. 74LS family IC's for 2-wire).
// I used 74LS164, for the reason that's what I had at hand.
// Connection description:
// SR output:
// Bit  #0   - N/C - not connected, used to hold a zero
// Bit  #1   - N/C
// Bit  #2   - connects to RS (Register Select) on the LCD
// Bits #3-6 - connects to LCD data inputs D4 - D7.
// Bit  #7   - enables the LCD enable-puls (via the diode-resistor AND "gate")
// 2 or 3 Pins required from the Arduino for Data, Clock and (optional) Enable
// 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.
//  Original project homepage: http://code.google.com/p/arduinoshiftreglcd/
// History
// 2011.10.29  fmalpartida - adaption of the library to the LCD class hierarchy.
// 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:
//             https://github.com/CapnBry/HeaterMeter/commit/c6beba1b46b092ab0b33bcbd0a30a201fd1f28c1
// 2009.07.30  raron - minor corrections to the comments.
//             Fixed timing to datasheet safe. Fixed keyword highlights.
// 2009.07.28  Mircho / raron - a new modification to the schematics, and a
//             more streamlined interface
// 2009.07.27  Thanks to an excellent suggestion from mircho at the Arduiono 
//             playgrond forum, the number of wires now required is only two!
// 2009.07.25  raron - Fixed comments. I really messed up the comments before 
//             posting this, so I had to fix it.
//             Renamed a function, but no improvements or functional changes.
// 2009.07.23  Incorporated some proper initialization routines
//             inspired (lets say copy-paste-tweaked) from LiquidCrystal
//             library improvements from LadyAda.
// 2009.05.23  raron - first version, but based mostly (as in almost verbatim)
//             on the "official" LiquidCrystal library.
// This library is only compatible with Arduino's SDK version 1.0
// @author F. Malpartida - fmalpartida@gmail.com
// ---------------------------------------------------------------------------

#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 );
    @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