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User provided i2cport
added user provided i2c port. changed int to uint8_t provided example program for custom i2c port
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‎LiquidCrystal_PCF8574.cpp

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/// \file LiquidCrystal_PCF8574.cpp
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/// \brief LiquidCrystal library with PCF8574 I2C adapter.
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///
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/// \author Matthias Hertel, http://www.mathertel.de
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/// \copyright Copyright (c) 2019 by Matthias Hertel.
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///
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/// ChangeLog see: LiquidCrystal_PCF8574.h
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#include "LiquidCrystal_PCF8574.h"
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/// Definitions on how the PCF8574 is connected to the LCD
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/// These are Bit-Masks for the special signals and background light
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#define PCF_RS 0x01
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#define PCF_RW 0x02
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#define PCF_EN 0x04
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#define PCF_BACKLIGHT 0x08
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// the 0xF0 bits are used for 4-bit data to the display.
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// a nibble is a half Byte
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LiquidCrystal_PCF8574::LiquidCrystal_PCF8574(uint8_t i2cAddr)
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{
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_i2cAddr = i2cAddr;
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_backlight = 0;
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_entrymode = 0x02; // like Initializing by Internal Reset Circuit
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_displaycontrol = 0x04;
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} // LiquidCrystal_PCF8574
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void LiquidCrystal_PCF8574::begin(uint8_t cols, uint8_t lines, TwoWire &wirePort)
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{
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_i2cPort = &wirePort; //Grab which port the user wants us to use
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_cols = ((cols>80)?(80):(cols));
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_lines = ((lines>4)?(4):(lines));
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uint8_t functionFlags = 0;
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_row_offsets[0] = 0x00;
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_row_offsets[1] = 0x40;
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_row_offsets[2] = 0x00 + cols;
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_row_offsets[3] = 0x40 + cols;
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if (lines > 1) {
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functionFlags |= 0x08;
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}
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// initializing the display
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_i2cPort->begin();
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_write2Wire(0x00, LOW, false);
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delayMicroseconds(50000);
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// after reset the mode is this
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_displaycontrol = 0x04;
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_entrymode = 0x02;
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// sequence to reset. see "Initializing by Instruction" in datatsheet
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_sendNibble(0x03);
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delayMicroseconds(4500);
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_sendNibble(0x03);
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delayMicroseconds(200);
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_sendNibble(0x03);
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delayMicroseconds(200);
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_sendNibble(0x02); // finally, set to 4-bit interface
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// Instruction: Function set = 0x20
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_send(0x20 | functionFlags);
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display();
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clear();
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leftToRight();
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} // begin()
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void LiquidCrystal_PCF8574::clear()
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{
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// Instruction: Clear display = 0x01
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_send(0x01);
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delayMicroseconds(1600); // this command takes 1.5ms!
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} // clear()
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void LiquidCrystal_PCF8574::init()
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{
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clear();
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} // init()
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void LiquidCrystal_PCF8574::home()
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{
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// Instruction: Return home = 0x02
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_send(0x02);
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delayMicroseconds(1600); // this command takes 1.5ms!
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} // home()
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/// Set the cursor to a new position.
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void LiquidCrystal_PCF8574::setCursor(uint8_t col, uint8_t row)
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{
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// check boundaries
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if ((col >= 0) && (col < _cols) && (row >= 0) && (row < _lines)) {
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// Instruction: Set DDRAM address = 0x80
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_send(0x80 | (_row_offsets[row] + col));
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}
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} // setCursor()
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// Turn the display on/off (quickly)
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void LiquidCrystal_PCF8574::noDisplay()
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{
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// Instruction: Display on/off control = 0x08
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_displaycontrol &= ~0x04; // display
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_send(0x08 | _displaycontrol);
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} // noDisplay()
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void LiquidCrystal_PCF8574::display()
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{
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// Instruction: Display on/off control = 0x08
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_displaycontrol |= 0x04; // display
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_send(0x08 | _displaycontrol);
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} // display()
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// Turns the underline cursor on/off
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void LiquidCrystal_PCF8574::cursor()
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{
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// Instruction: Display on/off control = 0x08
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_displaycontrol |= 0x02; // cursor
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_send(0x08 | _displaycontrol);
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} // cursor()
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void LiquidCrystal_PCF8574::noCursor()
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{
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// Instruction: Display on/off control = 0x08
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_displaycontrol &= ~0x02; // cursor
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_send(0x08 | _displaycontrol);
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} // noCursor()
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// Turn on and off the blinking cursor
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void LiquidCrystal_PCF8574::blink()
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{
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// Instruction: Display on/off control = 0x08
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_displaycontrol |= 0x01; // blink
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_send(0x08 | _displaycontrol);
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} // blink()
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void LiquidCrystal_PCF8574::noBlink()
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{
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// Instruction: Display on/off control = 0x08
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_displaycontrol &= ~0x01; // blink
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_send(0x08 | _displaycontrol);
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} // noBlink()
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// These commands scroll the display without changing the RAM
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void LiquidCrystal_PCF8574::scrollDisplayLeft(void)
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{
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// Instruction: Cursor or display shift = 0x10
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// shift: 0x08, left: 0x00
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_send(0x10 | 0x08 | 0x00);
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} // scrollDisplayLeft()
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void LiquidCrystal_PCF8574::scrollDisplayRight(void)
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{
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// Instruction: Cursor or display shift = 0x10
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// shift: 0x08, right: 0x04
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_send(0x10 | 0x08 | 0x04);
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} // scrollDisplayRight()
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// == controlling the entrymode
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// This is for text that flows Left to Right
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void LiquidCrystal_PCF8574::leftToRight(void)
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{
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// Instruction: Entry mode set, set increment/decrement =0x02
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_entrymode |= 0x02;
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_send(0x04 | _entrymode);
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} // leftToRight()
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// This is for text that flows Right to Left
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void LiquidCrystal_PCF8574::rightToLeft(void)
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{
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// Instruction: Entry mode set, clear increment/decrement =0x02
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_entrymode &= ~0x02;
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_send(0x04 | _entrymode);
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} // rightToLeft()
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// This will 'right justify' text from the cursor
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void LiquidCrystal_PCF8574::autoscroll(void)
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{
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// Instruction: Entry mode set, set shift S=0x01
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_entrymode |= 0x01;
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_send(0x04 | _entrymode);
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} // autoscroll()
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// This will 'left justify' text from the cursor
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void LiquidCrystal_PCF8574::noAutoscroll(void)
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{
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// Instruction: Entry mode set, clear shift S=0x01
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_entrymode &= ~0x01;
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_send(0x04 | _entrymode);
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} // noAutoscroll()
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/// Setting the brightness of the background display light.
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/// The backlight can be switched on and off.
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/// The current brightness is stored in the private _backlight variable to have it available for further data transfers.
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void LiquidCrystal_PCF8574::setBacklight(uint8_t brightness)
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{
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_backlight = brightness;
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// send no data but set the background-pin right;
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_write2Wire(0x00, true, false);
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} // setBacklight()
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// Allows us to fill the first 8 CGRAM locations
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// with custom characters
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void LiquidCrystal_PCF8574::createChar(uint8_t location, byte charmap[])
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{
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location &= 0x7; // we only have 8 locations 0-7
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// Set CGRAM address
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_send(0x40 | (location << 3));
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for (int i = 0; i < 8; i++) {
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write(charmap[i]);
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}
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} // createChar()
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/* The write function is needed for derivation from the Print class. */
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inline size_t LiquidCrystal_PCF8574::write(uint8_t ch)
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{
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_send(ch, true);
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return 1; // assume sucess
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} // write()
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// write either command or data
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void LiquidCrystal_PCF8574::_send(uint8_t value, bool isData)
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{
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// write high 4 bits
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_sendNibble((value >> 4 & 0x0F), isData);
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// write low 4 bits
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_sendNibble((value & 0x0F), isData);
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} // _send()
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// write a nibble / halfByte with handshake
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void LiquidCrystal_PCF8574::_sendNibble(uint8_t halfByte, bool isData)
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{
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_write2Wire(halfByte, isData, true);
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delayMicroseconds(1); // enable pulse must be >450ns
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_write2Wire(halfByte, isData, false);
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delayMicroseconds(37); // commands need > 37us to settle
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} // _sendNibble
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// private function to change the PCF8674 pins to the given value
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// Note:
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// you may change this function what the display is attached to the PCF8574 in a different wiring.
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void LiquidCrystal_PCF8574::_write2Wire(uint8_t halfByte, bool isData, bool enable)
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{
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// map the given values to the hardware of the I2C schema
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uint8_t i2cData = halfByte << 4;
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if (isData)
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i2cData |= PCF_RS;
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// PCF_RW is never used.
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if (enable)
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i2cData |= PCF_EN;
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if (_backlight > 0)
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i2cData |= PCF_BACKLIGHT;
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_i2cPort->beginTransmission(_i2cAddr);
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_i2cPort->write(i2cData);
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_i2cPort->endTransmission();
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} // write2Wire
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// The End.

‎LiquidCrystal_PCF8574.h

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/// \file LiquidCrystal_PCF8574.h
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/// \brief LiquidCrystal library with PCF8574 I2C adapter.
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///
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/// \author Matthias Hertel, http://www.mathertel.de
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///
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/// \copyright Copyright (c) 2019 by Matthias Hertel.\n
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///
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/// The library work is licensed under a BSD style license.\n
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/// See http://www.mathertel.de/License.aspx
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///
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/// \details
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/// This library is can drive a Liquid Cristal display based on the Hitachi HD44780 chip that is connected through a PCF8574 I2C adapter.
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/// This is given by many (not all) LCD adapters. This library uses the original Wire library for communication.
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/// The API if common to many LCD libraries and documented in https://www.arduino.cc/en/Reference/LiquidCrystal.
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/// and partially functions from https://playground.arduino.cc/Code/LCDAPI/.
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///
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/// ChangeLog:
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/// --------
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/// * 19.10.2013 created.
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/// * 05.06.2019 rewrite from scratch.
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/// * 16.12.2020 modified to provide user's chosen I2C hardware, changed int to unint8_t
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#ifndef LiquidCrystal_PCF8574_h
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#define LiquidCrystal_PCF8574_h
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#include "Arduino.h"
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#include <Wire.h>
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#include "Print.h"
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#include <stddef.h>
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#include <stdint.h>
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class LiquidCrystal_PCF8574 : public Print
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{
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public:
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LiquidCrystal_PCF8574(uint8_t i2cAddr);
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// note:
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// There is no sda and scl parameter for i2c in any api.
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// The Wire library has standard settings that can be overwritten by using Wire.begin(sda, scl) before calling LiquidCrystal_PCF8574::begin();
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// When using multiple I2C ports one can use
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// LiquidCrystal_PCF8574 lcd(0x27);
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// TwoWire Wire_1 = TwoWire();
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// Wire_1.begin(sdaPin, sclPin);
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// Wire_1.setClock(100000); // standard 100kHz speed
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// Wire_1.setClockStretchLimit(200000); // 200ms, for slow devices
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// lcd.begin(clos, rows, Wire_1);
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// Funtions from reference:
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void begin(uint8_t cols, uint8_t rows, TwoWire &wirePort = Wire);
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void init();
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void home();
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void setCursor(uint8_t col, uint8_t row);
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void cursor();
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void noCursor();
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void blink();
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void noBlink();
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void display();
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void noDisplay();
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void scrollDisplayLeft();
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void scrollDisplayRight();
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void autoscroll();
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void noAutoscroll();
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void leftToRight();
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void rightToLeft();
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void createChar(uint8_t, byte[]);
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// plus functions from LCDAPI:
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void clear(); // same as init()
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void setBacklight(uint8_t brightness);
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// support of Print class
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virtual size_t write(uint8_t ch);
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using Print::write;
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private:
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TwoWire * _i2cPort; //The generic connection to user's chosen I2C hardware
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// instance variables
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uint8_t _i2cAddr;
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uint8_t _backlight; ///< the backlight intensity
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uint8_t _cols; ///< number of cols of the display
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uint8_t _lines; ///< number of lines of the display
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uint8_t _entrymode; ///<flags from entrymode
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uint8_t _displaycontrol; ///<flags from displaycontrol
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uint8_t _row_offsets[4];
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// low level functions
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void _send(uint8_t value, bool isData = false);
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void _sendNibble(uint8_t halfByte, bool isData = false);
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void _write2Wire(uint8_t halfByte, bool isData, bool enable);
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};
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#endif

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