I am running 12 - DS18B20 1-wire temp probes with the arduino. I want to send the temperatures to a Creston PRO2 processor thru a RS232 shield, mounted on my arduino. My problem is that a program can’t be uploaded to the arduino with the RS232 installed. With a little experimenting I found I could install a switch between the 5v power output pin on the arduino and the power input on the RS232 while the RS232 is mounted. It seems to work vary reliably, at least for sending data out thru the RS232 line.
My question is can I power the RS232 using the digital output pins on the arduino.(Enough power) I can run 2 or more pins in parallel to increase power if need be.
If I can do this and I think I can, is there any way a running program can tell when a program is starting to be uploaded and turn those pins off, so I can successfully upload the new program?