This library allows an Arduino board to control LiquidCrystal displays (LCDs) based on the Hitachi HD44780 (or a compatible) chipset, which is found on most text-based LCDs, using one MCP23S17 port expander.
Info about the library https://electronza.com/mcp23s17-lcd-arduino-library/
You may also wish to read http://www.arduino.cc/en/Reference/LiquidCrystal
Copyright © 2006-2008 Hans-Christoph Steiner. All rights reserved. Copyright © 2010 Arduino LLC. All right reserved. Copyright © 2019 Teodor Costachioiu. All right reserved.
This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version.
This library 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 Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA