210 lines
7.6 KiB
C++
210 lines
7.6 KiB
C++
// ---------------------------------------------------------------------------
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// Created by Francisco Malpartida on 20/08/11.
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// Copyright 2011 - Under creative commons license 3.0:
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// Attribution-ShareAlike CC BY-SA
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//
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// This software is furnished "as is", without technical support, and with no
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// warranty, express or implied, as to its usefulness for any purpose.
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//
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// Thread Safe: No
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// Extendable: Yes
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//
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// @file LiquidCrystal_SR.h
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// Connects an LCD using 2 or 3 pins from the Arduino, via an 8-bit
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// ShiftRegister (SR from now on).
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//
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// @brief
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// This is a port of the ShiftRegLCD library from raron and ported to the
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// LCD library.
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//
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// The functionality provided by this class and its base class is identical
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// to the original functionality of the Arduino LiquidCrystal library and can
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// be used as such.
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//
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// Modified to work serially with the shiftOut() function, an 8-bit
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// unlatched, no-tristate, unidirectional SIPO (Serial-In-Parallel-Out)
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// shift register (IE a very simple SR), and an LCD in 4-bit mode.
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// Any such shift register should do (pref. 74LS family IC's for 2-wire).
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// I used 74LS164, for the reason that's what I had at hand.
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//
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// Connection description:
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//
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// SR output:
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// Bit #0 - N/C - not connected, used to hold a zero
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// Bit #1 - N/C
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// Bit #2 - connects to RS (Register Select) on the LCD
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// Bits #3-6 - connects to LCD data inputs D4 - D7.
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// Bit #7 - enables the LCD enable-puls (via the diode-resistor AND "gate")
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//
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// 2 or 3 Pins required from the Arduino for Data, Clock and (optional) Enable
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// If not using Enable, the Data pin is used for the enable signal by defining
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// the same pin for Enable as for Data. Data and Clock outputs/pins goes to
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// the shiftregister.
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// LCD RW-pin hardwired to LOW (only writing to LCD).
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// Busy Flag (BF, data bit D7) is not read.
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//
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// Original project homepage: http://code.google.com/p/arduinoshiftreglcd/
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//
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//
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// History
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// 2012.03.29 bperrybap - Added delays for faster fio shiftout (it got too fast)
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// AVR needed delay. cmd/write delays are based on CPU speed so it works on pic32.
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// Added code to support indicating two wire mode by using enable=data pin
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// (documentation indicated this as working)
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// Fixed incorrect use of 5x10 for default font - now matches original LQ library.
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// can now eliminate enable pin in constructor for two wire mode.
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// 2012.01.16 Florian Fida - faster digitalWrite/shiftOut
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// 2011.10.29 fmalpartida - adaption of the library to the LCD class hierarchy.
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// 2011.07.02 Fixed a minor flaw in setCursor function. No functional change,
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// just a bit more memory efficient.
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// Thanks to CapnBry (from google code and github) who noticed it.
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// URL to his version of shiftregLCD:
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// https://github.com/CapnBry/HeaterMeter/commit/c6beba1b46b092ab0b33bcbd0a30a201fd1f28c1
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// 2009.07.30 raron - minor corrections to the comments.
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// Fixed timing to datasheet safe. Fixed keyword highlights.
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// 2009.07.28 Mircho / raron - a new modification to the schematics, and a
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// more streamlined interface
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// 2009.07.27 Thanks to an excellent suggestion from mircho at the Arduino
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// playgrond forum, the number of wires now required is only two!
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// 2009.07.25 raron - Fixed comments. I really messed up the comments before
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// posting this, so I had to fix it.
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// Renamed a function, but no improvements or functional changes.
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// 2009.07.23 Incorporated some proper initialization routines
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// inspired (lets say copy-paste-tweaked) from LiquidCrystal
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// library improvements from LadyAda.
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// 2009.05.23 raron - first version, but based mostly (as in almost verbatim)
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// on the "official" LiquidCrystal library.
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//
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//
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// @author F. Malpartida - fmalpartida@gmail.com
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// ---------------------------------------------------------------------------
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#include <stdio.h>
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#include <string.h>
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#include <inttypes.h>
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#if (ARDUINO < 100)
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#include <WProgram.h>
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#else
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#include <Arduino.h>
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#endif
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#include "LiquidCrystal_SR.h"
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#include "FastIO.h"
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// CONSTRUCTORS
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// ---------------------------------------------------------------------------
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// Assuming 1 line 8 pixel high font
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LiquidCrystal_SR::LiquidCrystal_SR (uint8_t srdata, uint8_t srclock,
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uint8_t enable )
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{
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init ( srdata, srclock, enable, 1, 0 );
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}
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// PRIVATE METHODS
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// ---------------------------------------------------------------------------
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//
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// init
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void LiquidCrystal_SR::init(uint8_t srdata, uint8_t srclock, uint8_t enable,
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uint8_t lines, uint8_t font)
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{
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// Initialise private variables
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_two_wire = 0;
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_srDataRegister = fio_pinToOutputRegister(srdata);
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_srDataBit = fio_pinToBit(srdata);
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_srClockRegister = fio_pinToOutputRegister(srclock);
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_srClockBit = fio_pinToBit(srclock);
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if ((enable == TWO_WIRE) || (enable == srdata))
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{
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_two_wire = 1;
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_srEnableRegister = _srDataRegister;
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_srEnableBit = _srDataBit;
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}
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else
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{
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_srEnableRegister = fio_pinToOutputRegister(enable);
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_srEnableBit = fio_pinToBit(enable);
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}
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// Configure control pins as outputs
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// ------------------------------------------------------------------------
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_displayfunction = LCD_4BITMODE | LCD_1LINE | LCD_5x8DOTS;
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}
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//
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// shiftIt
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void LiquidCrystal_SR::shiftIt(uint8_t val)
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{
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if (_two_wire)
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{
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// Clear to get Enable LOW
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fio_shiftOut(_srDataRegister, _srDataBit, _srClockRegister, _srClockBit);
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}
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fio_shiftOut(_srDataRegister, _srDataBit, _srClockRegister, _srClockBit, val, MSBFIRST);
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// LCD ENABLE PULSE
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//
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// While this library is written with a shift register without an output
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// latch in mind, it can work in 3-wire mode with a shiftregister with a
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// latch. The shiftregister latch pin (STR, RCL or similar) is then
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// connected to the LCD enable pin. The LCD is (very likely) slower
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// to read the Enable pulse, and then reads the new contents of the SR.
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ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
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{
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fio_digitalWrite_HIGH(_srEnableRegister, _srEnableBit);
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delayMicroseconds (1); // enable pulse must be >450ns
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fio_digitalWrite_SWITCHTO(_srEnableRegister, _srEnableBit, LOW);
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} // end critical section
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}
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// PUBLIC METHODS
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// ---------------------------------------------------------------------------
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/************ low level data pushing commands **********/
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//
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// send
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void LiquidCrystal_SR::send(uint8_t value, uint8_t mode)
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{
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// Divide byte in two nibbles include the RS signal
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// and format it for shiftregister output wiring to the LCD
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// We are only interested in my COMMAND or DATA for myMode
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uint8_t myMode = ( mode == DATA ) ? SR_RS_BIT : 0; // RS bit; LOW: command. HIGH: character.
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if ( mode != FOUR_BITS )
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{
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shiftIt(myMode | SR_EN_BIT | ((value >> 1) & 0x78)); // upper nibble
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}
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shiftIt(myMode | SR_EN_BIT | ((value << 3) & 0x78)); // lower nibble
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/*
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* Add some delay since this code is so fast it needs some added delay
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* even on AVRs because the shiftout is shorter than the LCD command execution time.
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*/
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#if (F_CPU <= 16000000)
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if(_two_wire)
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delayMicroseconds ( 10 );
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else
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delayMicroseconds ( 17 ); // 3 wire mode is faster so it must delay longer
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#else
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delayMicroseconds ( 37 ); // commands & data writes need > 37us to complete
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#endif
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}
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//
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// setBacklightPin
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void LiquidCrystal_SR::setBacklightPin ( uint8_t pin, t_backlighPol pol )
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{ }
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//
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// setBacklight
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void LiquidCrystal_SR::setBacklight ( uint8_t mode )
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{ }
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