/// \file LiquidCrystal_PCF8574.cpp /// \brief LiquidCrystal library with PCF8574 I2C adapter. /// /// \author Matthias Hertel, http://www.mathertel.de /// \copyright Copyright (c) 2019 by Matthias Hertel. /// /// ChangeLog see: LiquidCrystal_PCF8574.h #include "LiquidCrystal_I2C.h" // #include LiquidCrystal_PCF8574::LiquidCrystal_PCF8574(uint8_t i2cAddr) { // default pin assignment init(i2cAddr, 0, 1, 2, 4, 5, 6, 7, 3); } // LiquidCrystal_PCF8574 // constructors, which allows to redefine bit assignments in case your adapter is wired differently LiquidCrystal_PCF8574::LiquidCrystal_PCF8574(uint8_t i2cAddr, uint8_t rs, uint8_t enable, uint8_t d4, uint8_t d5, uint8_t d6, uint8_t d7, uint8_t backlight) { init(i2cAddr, rs, 255, enable, d4, d5, d6, d7, backlight); } // LiquidCrystal_PCF8574 LiquidCrystal_PCF8574::LiquidCrystal_PCF8574(uint8_t i2cAddr, uint8_t rs, uint8_t rw, uint8_t enable, uint8_t d4, uint8_t d5, uint8_t d6, uint8_t d7, uint8_t backlight) { init(i2cAddr, rs, rw, enable, d4, d5, d6, d7, backlight); } // LiquidCrystal_PCF8574 void LiquidCrystal_PCF8574::init(uint8_t i2cAddr, uint8_t rs, uint8_t rw, uint8_t enable, uint8_t d4, uint8_t d5, uint8_t d6, uint8_t d7, uint8_t backlight) { _i2cAddr = i2cAddr; _backlight = 0; _entrymode = 0x02; // like Initializing by Internal Reset Circuit _displaycontrol = 0x04; _rs_mask = 0x01 << rs; if (rw != 255) _rw_mask = 0x01 << rw; else _rw_mask = 0; _enable_mask = 0x01 << enable; _data_mask[0] = 0x01 << d4; _data_mask[1] = 0x01 << d5; _data_mask[2] = 0x01 << d6; _data_mask[3] = 0x01 << d7; if (backlight != 255) _backlight_mask = 0x01 << backlight; else _backlight_mask = 0; } // init() void LiquidCrystal_PCF8574::begin(uint8_t cols, uint8_t lines, TwoWire &wirePort) { _i2cPort = &wirePort; //Grab which port the user wants us to use _cols = min(cols, (uint8_t)80); _lines = min(lines, (uint8_t)4); uint8_t functionFlags = 0; _row_offsets[0] = 0x00; _row_offsets[1] = 0x40; _row_offsets[2] = 0x00 + cols; _row_offsets[3] = 0x40 + cols; if (lines > 1) { functionFlags |= 0x08; } // initializing the display _i2cPort->begin(); _write2Wire(0x00, LOW, false); delayMicroseconds(50000); // after reset the mode is this _displaycontrol = 0x04; _entrymode = 0x02; // sequence to reset. see "Initializing by Instruction" in datasheet _sendNibble(0x03); delayMicroseconds(4500); _sendNibble(0x03); delayMicroseconds(200); _sendNibble(0x03); delayMicroseconds(200); _sendNibble(0x02); // finally, set to 4-bit interface // Instruction: Function set = 0x20 _send(0x20 | functionFlags); display(); clear(); leftToRight(); } // begin() void LiquidCrystal_PCF8574::clear() { // Instruction: Clear display = 0x01 _send(0x01); delayMicroseconds(1600); // this command takes 1.5ms! } // clear() void LiquidCrystal_PCF8574::home() { // Instruction: Return home = 0x02 _send(0x02); delayMicroseconds(1600); // this command takes 1.5ms! } // home() /// Set the cursor to a new position. void LiquidCrystal_PCF8574::setCursor(uint8_t col, uint8_t row) { // check boundaries if ((col < _cols) && (row < _lines)) { // Instruction: Set DDRAM address = 0x80 _send(0x80 | (_row_offsets[row] + col)); } } // setCursor() // Turn the display on/off (quickly) void LiquidCrystal_PCF8574::noDisplay() { // Instruction: Display on/off control = 0x08 _displaycontrol &= ~0x04; // display _send(0x08 | _displaycontrol); } // noDisplay() void LiquidCrystal_PCF8574::display() { // Instruction: Display on/off control = 0x08 _displaycontrol |= 0x04; // display _send(0x08 | _displaycontrol); } // display() // Turns the underline cursor on/off void LiquidCrystal_PCF8574::cursor() { // Instruction: Display on/off control = 0x08 _displaycontrol |= 0x02; // cursor _send(0x08 | _displaycontrol); } // cursor() void LiquidCrystal_PCF8574::noCursor() { // Instruction: Display on/off control = 0x08 _displaycontrol &= ~0x02; // cursor _send(0x08 | _displaycontrol); } // noCursor() // Turn on and off the blinking cursor void LiquidCrystal_PCF8574::blink() { // Instruction: Display on/off control = 0x08 _displaycontrol |= 0x01; // blink _send(0x08 | _displaycontrol); } // blink() void LiquidCrystal_PCF8574::noBlink() { // Instruction: Display on/off control = 0x08 _displaycontrol &= ~0x01; // blink _send(0x08 | _displaycontrol); } // noBlink() // These commands scroll the display without changing the RAM void LiquidCrystal_PCF8574::scrollDisplayLeft(void) { // Instruction: Cursor or display shift = 0x10 // shift: 0x08, left: 0x00 _send(0x10 | 0x08 | 0x00); } // scrollDisplayLeft() void LiquidCrystal_PCF8574::scrollDisplayRight(void) { // Instruction: Cursor or display shift = 0x10 // shift: 0x08, right: 0x04 _send(0x10 | 0x08 | 0x04); } // scrollDisplayRight() // == controlling the entrymode // This is for text that flows Left to Right void LiquidCrystal_PCF8574::leftToRight(void) { // Instruction: Entry mode set, set increment/decrement =0x02 _entrymode |= 0x02; _send(0x04 | _entrymode); } // leftToRight() // This is for text that flows Right to Left void LiquidCrystal_PCF8574::rightToLeft(void) { // Instruction: Entry mode set, clear increment/decrement =0x02 _entrymode &= ~0x02; _send(0x04 | _entrymode); } // rightToLeft() // This will 'right justify' text from the cursor void LiquidCrystal_PCF8574::autoscroll(void) { // Instruction: Entry mode set, set shift S=0x01 _entrymode |= 0x01; _send(0x04 | _entrymode); } // autoscroll() // This will 'left justify' text from the cursor void LiquidCrystal_PCF8574::noAutoscroll(void) { // Instruction: Entry mode set, clear shift S=0x01 _entrymode &= ~0x01; _send(0x04 | _entrymode); } // noAutoscroll() /// Setting the brightness of the background display light. /// The backlight can be switched on and off. /// The current brightness is stored in the private _backlight variable to have it available for further data transfers. void LiquidCrystal_PCF8574::setBacklight(uint8_t brightness) { _backlight = brightness; // send no data but set the background-pin right; _write2Wire(0x00, true, false); } // setBacklight() // Allows us to fill the first 8 CGRAM locations // with custom characters void LiquidCrystal_PCF8574::createChar(uint8_t location, uint8_t charmap[]) { location &= 0x7; // we only have 8 locations 0-7 // Set CGRAM address _send(0x40 | (location << 3)); for (uint8_t i = 0; i < 8; i++) { write(charmap[i]); } } // createChar() #ifdef __AVR__ // Allows us to fill the first 8 CGRAM locations // with custom characters stored in PROGMEM void LiquidCrystal_PCF8574::createChar_P(uint8_t location, const uint8_t *charmap) { PGM_P p = reinterpret_cast(charmap); location &= 0x7; // we only have 8 locations 0-7 _send(0x40 | (location << 3)); for (int i = 0; i < 8; i++) { uint8_t c = pgm_read_byte(p++); write(c); } } // createChar_P() #endif /* The write function is needed for derivation from the Print class. */ inline size_t LiquidCrystal_PCF8574::write(uint8_t ch) { _send(ch, true); return 1; // assume success } // write() // write either command or data void LiquidCrystal_PCF8574::_send(uint8_t value, bool isData) { // An I2C transmission has a significant overhead of ~10+1 I2C clock // cycles. We consequently only perform it only once per _send(). _i2cPort->beginTransmission(_i2cAddr); // write high 4 bits _writeNibble((value >> 4 & 0x0F), isData); // write low 4 bits _writeNibble((value & 0x0F), isData); _i2cPort->endTransmission(); } // _send() // write a nibble / halfByte with handshake void LiquidCrystal_PCF8574::_writeNibble(uint8_t halfByte, bool isData) { // map the data to the given pin connections uint8_t data = isData ? _rs_mask : 0; // _rw_mask is not used here. if (_backlight > 0) data |= _backlight_mask; // allow for arbitrary pin configuration if (halfByte & 0x01) data |= _data_mask[0]; if (halfByte & 0x02) data |= _data_mask[1]; if (halfByte & 0x04) data |= _data_mask[2]; if (halfByte & 0x08) data |= _data_mask[3]; // Note that the specified speed of the PCF8574 chip is 100KHz. // Transmitting a single byte takes 9 clock ticks at 100kHz -> 90us. // The 37us delay is only necessary after sending the second nibble. // But in that case we have to restart the transfer using additional // >10 clock cycles. Hence, no additional delays are necessary even // when the I2C bus is operated beyond the chip's spec in fast mode // at 400 kHz. _i2cPort->write(data | _enable_mask); // delayMicroseconds(1); // enable pulse must be >450ns _i2cPort->write(data); // delayMicroseconds(37); // commands need > 37us to settle } // _writeNibble // write a nibble / halfByte with handshake void LiquidCrystal_PCF8574::_sendNibble(uint8_t halfByte, bool isData) { _i2cPort->beginTransmission(_i2cAddr); _writeNibble(halfByte, isData); _i2cPort->endTransmission(); } // _sendNibble // private function to change the PCF8574 pins to the given value void LiquidCrystal_PCF8574::_write2Wire(uint8_t data, bool isData, bool enable) { if (isData) data |= _rs_mask; // _rw_mask is not used here. if (enable) data |= _enable_mask; if (_backlight > 0) data |= _backlight_mask; _i2cPort->beginTransmission(_i2cAddr); _i2cPort->write(data); _i2cPort->endTransmission(); } // write2Wire // The End.