I bought a LCD shield, compatible with the DFRobot LCD Keypad Shield. Then I attached this shield to my Arduino Uno board.
I was trying to figure out how to access the Arduino pins through the shield, therefore I make a sketch that makes a led on digital pin 3 blink.
The system works if I connect the jumper wire to the spot marked with A in the picture, as expected, as that is the pin directly inserted into the Arduino header.
Then, I tried to attach the wire to the hole marked with B, as that is next to A, but the system didn't work. I had to insert the jumper wire as shown in the picture.
To me, that is totally counterintuitive as the hole I am using is next to pin 4 of Arduino, not pin 3.
Am I missing something? How could I have anticipated that? Is there a standard for how shields map Arduino pins?
I bought it on eBay from a supplier based in Hong Kong.
Yes, I found the schematics - I have attached it.
But I can't find it in there how I could find out about the issue I am talking about - don't you need the PCB layout to see that? - sorry I am a newbie.