An Arduino and a data radio can make a great remote sensor node. Often in such situations, the hardware ends up installed somewhere hard to get to – be it in a light fitting, behind a wall, or secreted somewhere outdoors. Not places that you’d want to squeeze a cable repeatedly into while debugging.
Using the NRF24L01 chip with the Arduino is a popular choice to add wireless communications to a small project. By installing one of these radios on both the remote hardware and a local Arduino connected to the programming computer, it’s possible to remotely flash the Arduino without any physical contact whatsoever using Optiboot.
The writeup is comprehensive and covers both the required hardware setup for both ends of the operation as well as how to install the relevant bootloaders. If you’re already using the NRF24L01 in your projects, this could be the ideal solution to your programming woes. Perhaps you’re using a different platform though – like an Arduino on WiFi? Don’t worry – you can do OTA updates that way, too.