I bought this Arduino clone recently and it has lot of extra holes for pins, but some of them I don't know what they do. There was no instruction manual that came with it. Here's a picture of it, I added a red rectangle around the ones I don't know. (4 pins with X1, SCL/SDA, AREF and blank pin in the bottom)
I thought I could use the pins SCL SDA 5V GND with my I2C LCD Display because the names of the pins are the same on it. Could it work? Usually I use analog pins to connect the display, does that mean that by using it some analog pins will be used indirectly? I didn't try connecting it because I don't want it to break.
What do these pins do?