I need help for my home automation project. It's a new installation all build for the automation project. What I mean is that lights have 220v capable cabling running to the relay groups and relay groups are connected to the Arduino Mega 2560 with internet cables. Relay groups (special relay groups designed for Arduino) have they're own power supply and function without problem when input gets a ground connection. In this principle I connected 2 relay groups and they're functioning without any problems. As I connected the third relay group to the Arduino I encountered "interesting" error. When I power up the relay group I can't upload the software to the Arduino. If I disconnect the +5V power of the relay group the program uploads without problems. After that when I connect the power to the relay group it function as programed as well.
When the power to the relay group is connected and I try to upload the software all I get is one flash or red power led and one flash of green TX or RX led. The software waits for something, but nothing happens, only every 10 or so seconds the TX or RX led flashes. All I can do is to disconnect the USB cable, the software gets an time out error naturally and I have to restart the Arduino after that it resumes with the old software without any errors.
Did some one had that kind of problem? please give me a hint what could be wrong...
P.s. I'm not using the Arduino communication pins (0 and 1).