I have a bunch of Unos and sensors around the farm. Occasionally I have to upload new updates to the sketch. Its very cold and snow is on the ground, lugging a laptop to each station with heavy snow falling is a pain in the butt.
Is there some way I can make a small battery powered pocket / portable "uploader" that I can plug into the Uno serial ports at each station to just upload the new sketches, thus do away with the big laptop?
Thank You.
Do you have a serial port or are you referring to the USB port on the target Unos?
I've seen a few posts regarding what you want to achieve. You can do a search, not sure which search terms to use.
If you're referring to USB on the target Unos, you will need a USB host shield on your 'pocket' programmer to be able to communicate.
Here's a tutorial that will show you how to make a standalone uploader that will program your Unos with a .hex file from an SD card:
https://www.gammon.com.au/forum/?id=11638
One of our forum moderators makes and sells pre-made Standalone Programmers based on the same code and design here:
http://www.crossroadsfencing.com/BobuinoRev17/Programmer.html
OP mentioned 'serial'. The stuff that you refer to uses ICSP which might not be feasible; it's the reason why I did not refer to it (yet).