Hello, I have two GSM modules relay that are using arduino nano (made in usa version) on it working excellent. Now I need 5 more and I get a lot of arduino nano (clone chinesse) with ch340g chip. and I'm having a problem with D13 pin when I connect 5v and USB to PC at same time, this pin is an output and the led13 begin to blinking too.
When I use this with 5v external supply it works fine. And when I use it only with USB to PC it work fine. But both at same time is the problem.
I begin to check 2 or 3 arduino nano clone only connecting 5v power supply to 5v+ pin and Gnd.. and connecting USB and all these with the same fail. But when I test the Original it never happens.
I also tried connecting 7v to Vin Pin and the same fail.
I do not have enough knowledge in electronics to know what happens, I'm searching for two days in google and I cant find any similar.
Has someone had this problem?
Thanks a lot.
This are the pictures of my nanos.
