I'm looking for a better way to upload code to a 4 pin (5v, Ground, Position 1 output and Position 2 Output) automotive shaft position sensor that is completely sealed with resin. Both outputs are 0.25-4.75 analog signals.
Components: Nano, Magnetic Position Sensor with external magnet mounted on end of shaft, 2 Channel DAC. The first 50 sensors can't be updated if it malfunctions because I don't want extra wires or USB hanging out. Now I've added some hardware and can do an upload using a FT232 sending it directly up the pigtail. The power and ground didn't change but I use the other two output wires for RX and TX pins D0 and D1. Because of that there is a momentary button hiding in the pigtail if you know where to push to engage reset for the upload. The hidden button is not a good solution. I have many ESP board variations and tried all I could to get the ESP 01S uploading the NANO but no luck.
Wireless is nice but won't be a common task so I'm fine with a physical connection. Just can't have the buttons or extra wires. Any info on how I can accomplish this is appreciated!