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Jérôme Delacotte
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libraries/hd44780/hd44780ioClass/hd44780_HC1627_I2C.h
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libraries/hd44780/hd44780ioClass/hd44780_HC1627_I2C.h
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// vi:ts=4
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// ---------------------------------------------------------------------------
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// hd44780_HC1627_I2C.h - hd44780_HC1627_I2C i/o subclass for hd44780 library
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// Copyright (c) 2020 Bill Perry
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//
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// The API functionality provided by this library class is compatible
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// with the API functionality of the Arduino LiquidCrystal library.
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//
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// ---------------------------------------------------------------------------
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//
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// This file is part of the hd44780 library
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//
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// hd44780_HC1627_I2C is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation version 3 of the License.
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//
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// hd44780_HC1627_I2C is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with hd44780_HC1627_I2C. If not, see <http://www.gnu.org/licenses/>.
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//
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// ---------------------------------------------------------------------------
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//
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// It implements all the hd44780 library i/o methods to control an LCD based
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// on the Tsingtek Display Co HC1627 LCD devices in i2c mode which have
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// a native I2C interface rather than use a simple I2C i/o expander chip
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// such as a PCF8574 or MCP23008
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// This device uses two i2c address:
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// - base address for RS clear
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// - one higher for RS set
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// The communication interface is very simple:
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// 8 bit data is sent using the base address
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// command/status use the base address +1
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//
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// Here are examples of such a device:
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// HC1627-B-LWH-I2C-30
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// HC1627_I2C-SYH-I2C-30
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// http://dvtecnologia.com.br/imagens/HC1627_I2C-SYH-I2C-30_Eng%2CA.pdf
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// This device has 2 address pins to configure the base address.
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//
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// The configurable base address can be:
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// 0x38, 0x3A, 0x3C, 0x3E
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// It overlaps with the addresses for the PCF8574A and PCF2116/PCF2119x
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// NOTE:
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// This device needs pullups on the bus signals.
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// While it will usually work on an AVR platform without external pullups,
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// it doesn't always work.
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//
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// The I2C can only control the LCD and does not have the capability
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// to control the backlight so the backlight will always remain on.
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//
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// 2020.06.26 bperrybap - initial creation (hd44780_IIClcd)
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//
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// @author Bill Perry - bperrybap@opensource.billsworld.billandterrie.com
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//
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// ---------------------------------------------------------------------------
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#ifndef hd44780_HC1627_I2C_h
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#define hd44780_HC1627_I2C_h
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#if (ARDUINO < 101) && !defined(MPIDE)
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#error hd44780_HC1627_I2C i/o class requires Arduino 1.0.1 or later
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#endif
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class hd44780_HC1627_I2C : public hd44780
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{
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public:
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// ====================
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// === constructors ===
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// ====================
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hd44780_HC1627_I2C(uint8_t i2c_addr=0) : _Addr(i2c_addr) {} // zero addres means auto locate
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private:
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// ====================
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// === private data ===
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// ====================
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uint8_t _Addr; // I2C base Address of the LCD
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// ==================================================
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// === hd44780 i/o subclass virtual i/o functions ===
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// ==================================================
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//
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// Note:
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// It is not possible to control the backlight nor
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// is it possible to read from the device.
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// so iosetbacklight() and ioread()
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// will not be defined and will use the defaults in
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// hd44780
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// ioinit() - Returns non zero if initialization failed.
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int ioinit()
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{
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int status;
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/*
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* First, initialize the i2c (Wire) library.
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* This really shouldn't be here
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* because Wire.begin() should only be called once, but
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* unfortunately, there is no way to know if anybody
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* else has called this.
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* I believe that it is unreasonable to require the the user
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* sketch code to do it, because all that should change between
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* interfaces should be the constructor
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* So we go ahead and call it here.
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*/
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Wire.begin();
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/*
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* If i2c address was not specified go try to locate device
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*/
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if(!_Addr)
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{
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if( !(_Addr = LocateDevice())) // failed to find device
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{
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return(hd44780::RV_ENXIO);
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}
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}
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/*
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* Check to see if the device is responding
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*/
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Wire.beginTransmission(_Addr);
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if( (status = Wire.endTransmission()) )
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{
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if(status == 1)
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status = hd44780::RV_EMSGSIZE;
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else if(status == 2)
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status = hd44780::RV_ENXIO;
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else
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status = hd44780::RV_EIO;
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}
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/*
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* this device only runs in 8 bit mode
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*/
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_displayfunction = HD44780_8BITMODE;
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return ( status );
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}
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//
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// iowrite(type, value) - send either a command or data byte to lcd
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// returns zero on success, non zero on failure
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int iowrite(hd44780::iotype type, uint8_t value)
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{
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uint8_t addr;
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/*
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* No need to look for 4 bit commands as all bits are already in
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* proper upper nibble and unsued bits are zero.
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* This allows the special 4 bit commands to be sent "As is" when
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* using an 8 bit interface - which is what this i2c LCD uses.
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*/
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if(type == hd44780::HD44780_IOdata)
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{
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addr = _Addr + 1; // RS bit is set by using 1 higher address
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}
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else
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{
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addr = _Addr; // RS is clear when using base address
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}
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/*
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* ensure that previous LCD instruction finished.
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* There is a 25us offset since there will be at least 1 byte
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* (the i2c address) transmitted over i2c before the next LCD instruction
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* information could get to the LCD.
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* At 400Khz (max rate supported by the LCD) 8 bits plus start and stop
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* bits is 25us.
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* So there is at least 25us of time overhead in the physical interface.
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*/
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waitReady(-25);
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/*
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* Send the next LCD instruction
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*/
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Wire.beginTransmission(addr);
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Wire.write(value); // send data/cmd
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if(Wire.endTransmission())
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return(hd44780::RV_EIO);
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else
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return(hd44780::RV_ENOERR);
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}
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// ================================
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// === internal class functions ===
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// ================================
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// LocateDevice() - Locate I2C LCD device
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uint8_t LocateDevice()
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{
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uint8_t error, address;
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// Search for 4 base address pairs
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for(address = 0x38; address <= 0x3E; address += 2 )
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{
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Wire.beginTransmission(address);
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error = Wire.endTransmission();
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// chipkit i2c screws up if you do a beginTransmission() too quickly
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// after an endTransmission()
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// below 20us will cause it to fail,
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// we use delay(1) here to accomdate that as well as ensure that
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// systems with watchdog timers like ESP8266 won't have issues.
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delay(1);
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if(error == 0) // if no error we found something
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{
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return(address);
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}
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}
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return(0); // could not locate device address
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}
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}; // end of class definition
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#endif
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