Systech Illinois ZR800 serial data access

Copyright (c) 2025 Ketut P. Kumajaya.  All right reserved.

Reads the ZR800 oxygen and temperature readings via serial port, then displays
them on the LCD and also sends them to the analog output. It has basic
features to change the LCD brightness, the baudrate, the oxygen and
temperature reading range, and also features to calibrate the analog output.

How to compile:
1. Download and install official Microsoft's Visual Studio Code
2. Open VSCode Extension Manager
3. Search for official PlatformIO IDE extension
4. Install PlatformIO IDE
5. In PlatformIO Home - Platforms - Advanced Installation, paste:
   https://github.com/kumajaya/platform-atmelsam#industruino and click Install
6. Industruino D21G and Industruino 4-20mA.ker will be available in PlatfomrIO
   board selection menu
7. Download the source code of ZR800 project from the repository:
   https://github.com/kumajaya/zr800
8. Open ZR800 project from PlatformIO Home, Build, and Upload to Industruino D21G