I have a 3D printer running RAMPS attached to my programming computer at all times. It hasn't happened yet, but I'm quite concerned with accidentally overwriting its firmware at some point when I intend to work on another board. Is there any way to ensure that the IDE doesn't ever write to that specific device or COM port? Or maybe something on the board?
Thanks!
finchamp:
Or maybe something on the board?
The 3D printer board? Just disconnect it.
All Arduino boards (as far as I know) that have a TTL-USB chip use a DTR line on that chip that is connected to the reset pin of the main micro; cut the DTR track from theTTL- USB chip to the main micro and it will not reset when instructed by the IDE.
There is a DTR Enable solder jumper on many boards for that. Cut the trace between the pads.
DTR line connects to a 0.1uF (100nF) cap, that then goes to Reset.
Would disabling auto reset with a 10uf cap from reset to ground be a less permanent solution?
I just looked, and CrossRoads is correct. There is a Reset-EN pair of solder pads with a trace joining them. Cutting the trace is by far the least permanent way to make this happen; if you need to reflash it, just solder the pads together. After you're done, desolder.
Thanks everybody!