Hi @mochav. While it is possible to download the compiled program from the Arduino board, it is not possible to recover your original sketch from that file. You could get the assembly listing from the compiled program, but this will have no resemblance to your sketch. It would be faster to just write your sketch all over again than to convert the assembly back into a standard Arduino sketch.
So if you only want to get the compiled program so you can upload it in an unmodified state to other Arduino boards that use the same configuration as your current board, then this is worth doing and I can provide instructions. But if you need your actual code back then I'm sorry to tell you that this is not the solution.
However, it might be possible to recover your code in a different way. Arduino IDE copies your sketch to a temporary folder during the compilation process. It is possible the full sketch is still stored in that folder. If you are using Arduino IDE 2.x with Windows. it would be at this location:
C:\Users\<username>\AppData\Local\Temp\arduino_build_<some number>\<sketch name>\<sketch name>.ino.cpp
(where <username> is your Windows username, and <some number> is some characters used to differentiate the folder name, and <sketch name> is the name of the sketch)
For example:
C:\Users\per\AppData\Local\Temp\arduino_build_386170\sketch\MySketch.ino.cpp
If you are using a different operating system or IDE version, I can provide the appropriate path.
Note that a .cpp file extension has been appended to the original sketch filename.
You can try doing a search through that folder for the filename of your sketch.
This storage location is temporary in nature. It might be overwritten by Arduino IDE or deleted by your operating system at any time. So if you are going to try to recover the sketch from this location, you should do it as soon as possible and immediately move it to a safe location once you find it. You should also be careful to avoid performing actions that would trigger the loss of the data before attempting the recovery:
- Do not compile or upload your sketch in Arduino IDE.
- Do not close Arduino IDE.
- Do not shut down or restart your computer.
- Do not perform any operations to automatically free up disk space.
If you find the sketch file in the temporary folder, you will notice Arduino IDE made some changes in the code. These changes are minimal so it will be easy to convert the code back to your original sketch. We can help you out with that if you have trouble.