saylur:
I am working on a home automation project in which I have a Mega (2560) and a Yun. I am powering the Mega USB input from a Kara Mobile regulated switching 5v supply with a hacked USB cable (+/- 5v only - no data). I saw no discussion about the USB shield so I also connected the hacked USB cable connector shield/shell to the minus 5v line of the supply. All seems OK to this point. I powered the Yun “Vin” from the Mega’s 5 volt buss. This also seems to work OK but my problem is the large amount of current the Yun will be pulling and hence total power coming into the Mega.
It seems that I could create 2 hacked USB cables in parallel on the regulated supply output to separately feed the two controllers. Question: if doing this, should the the USB connector shield/shell be connected to the supply minus 5 volt line in both hacked cables? Should there also be an additional ground between the Yun and Mega, since I hope to have them communicating in the future?
Alternately, it seems I could directly wire the regulated 5v to the Mega’s 5v buss and also to the “Vin” on the Yun with the Grounds connected together. However, this would bypass any internal fuse/protection that the USB input would provide. Any recommendations would be most appreciated.
Thanks.
You also have to remember that a USB 2 port can only output 500mA. Running the two from one port may overload the port. I understand that USB 3 ports (the blue ones) can output 1A.