A Lazarus code to send serial data to arduino and get feedback. An Arduino code to get the serial data, send PWM to a led and send back the same data via serial. You'll need to install 5dpo Serial package on Lazaus. http://wiki.lazarus.freepascal.org/5dpo

Arduino Tutorial: Read Button and Send Data to PC

A beginner's reference to the programming syntax of the Arduino microcontroller. Includes information on program structure, variables, datatypes, arithmetic, constants, flow control, and most of the common functions of the core library. Also includes an appendix with schematics and simple programs for several common tasks.