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