There are many KISS TNCs available online, both commercially and as DIY projects. While most DIY options offer high-quality hardware, they often lack one critical component—open-source firmware. Many projects provide only the HEX file for pre-programmed microcontrollers, limiting the ability to modify or understand the underlying code. 

This led me to embark on my own KISS TNC project, inspired by the work of KV4P. I replicated his audio interface for APRS, but when it came to the firmware, I wanted a fully customizable solution. 

To kickstart the development, I experimented with AI-generated code. I provided OpenAI with my project details, including the ESP32 pinout, and asked for a simple KISS TNC implementation. The initial results were promising but required further refinement. Through multiple iterations, I improved the code to better align with the project’s needs.