How do identify an Arduino counterfeit?

How to cut traces and wire jumpers on Arduino Shield PCB

• I'm a total hardware engineering noob who's getting into Arduino development. I have an Electric Imp connected to the Arduino via a https://www.sparkfun.com/products/11401, which works great. However, I've added another shield that conflicts with the pins that are used by the Electric Imp for software serial IO. The Imp shield says that I can cut a trace and wire a jumper to use hardware serial on two open ports instead. I've never done this before – can someone give explicit steps as to what I need to do? - http://forums.electricimp.com/discussion/comment/12650#Comment_12650 mentions what is needed, but I don't know how to read a schematic. - Someone has done what I think is the jumper part http://www.instructables.com/id/IMP-ERSONATOR-Electric-Imp-Arduino-Wave-Shiel/step2/Add-Jumper-Wires-to-Imp-Shield/ but no mention of cutting the traces. It's a very similar project to mine.

• Answer:

  If you don't know how to read a schematic, this is a great way to start learning! http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Dev/Arduino/Shields/electric-imp-shield-v11.pdf; SJ1 and SJ2, mentioned in the thread you linked, are the symbols in the top-right. They have similar symbols to all the other components, but they actually just correspond to the sections labeled RX and TX on the underside of the board, in the bottom-left of https://dlnmh9ip6v2uc.cloudfront.net//assets/parts/7/1/8/4/11401-03.jpg The narrow trace connecting two of the pads in the RX section connects the Imp to Arduino pin 8, which is apparently the RX pin for the Arduino's software-emulated serial port. (So it's labeled RX, even though the Imp itself is transmitting on that pin.) The third pad is connected to Arduino pin 0 and nothing else. It sounds like you want to switch the serial connection from pins 8/9 to pins 0/1, right? Then all you need to do is: 1. Cut the two traces with a knife -- an X-Acto or similar craft knife, or even a pocket knife, should work fine. Depending on the thickness of the trace and soldermask, you might need to sort of scratch it out. 2. Check with a multimeter that there's no continuity between the pads, to make sure you've cut all the way through. 3. Put a blob of solder (aka "solder bridge") between the center "RX" pad and the pin-0 pad. Don't go overboard; use just enough solder to nicely cover both pads. Repeat for "TX" and pin-1. 4. Test continuity again between Arduino pins 0/1 and Imp pins P5/P7 to make sure the soldered connection is good. If you have problems making the solder bridge, you can always do what the person in your last link did and use wires instead, but this way is a little neater. Good luck!