I found a guide on make on how to solder it but before I start melting metal I thought I'd ask a few questions

-The caps... why?
-The LEDs.. how do I use them? are they hooked up to the 1k resistors? and how could I get any use of them i.e. where could I connect the wires to them?
-THe switches. I understand one is connected to the ICSP pins for reset, where could I plug wires in to get any use out of the second?
-ICSP, afaik only one of the pins is connected to the real ICSP on the other side of the arduino.. so how are these useful?
-the 3 female headers aren't connected to anything.. I imagine they're just for more pins for 5v, gnd, and whatever you want?


--The caps:
The capacitors tend to smooth out ripples in the supply voltage, which remain after you have converted AC (bumpy) to DC (flat, ideally). They can be omitted, if you like, as they supplement the capacitors on the Arduino board itself.

--The LEDs:
Are hooked up to 100ohm resistors, not 1K (at least on my protoshield). You will have to solder a small piece of wire into the holes indicated on your instructions, and then you can simply connect that wire into any pin on the board, and if there's voltage there, the LED will light up. Handy.

--The switches:
The second switch is connected to ground, as I remember. You will have to solder a wire into it to be able to use it.

useful if you don't want to program your arduino via usb, I think. I've never used them.

--The three additional female headers: one is connected to +5V, the other two to ground. Handy, because otherwise you only have one pin of each type, so you'd have to run a wire out to a row on your breadboard.

I don't know what instructions you're using, but the ones on the Adafruit website are excellent, and explain all this:

Hope this helps.

hm, the resistors I got in mine are definitely 1k (brown black red ) and it looks like that's what they use in the link you sent me.

Also looks like the LEDs and the switch are all grounded, so there's limited usefulness but still good for debugging

The capacitors.. The look like they're hooked up to the reset pin, and the +5v rail... wouldn't that break both circuits since the current is DC by this point?


I took another look at the built-in resistors, and you're right, they are 1k on mine. The point being to limit the amount of current going through the diode so that you don't burn out your LED, of course.

Also, the capacitors are connected across +5V to ground, although since the reset switch is also connected to ground they are in a sense connected to the reset switch.

w.r.t. the switch, remember that you can connect a ~10Kohm pullup resistor between +5V and the sensor side of the switch, and thus have a logical 1 when the switch is unpressed, and a logical 0 when it is pressed. Quite handy when you need a stand-in for some other sensor that you haven't purchased yet.

btw, make sure you don't solder on the header pins on the wrong side of the board. I did that when I was wiring up mine and they're a real pain to get off if you do them wrong ::).

I don't even need the pullup :slight_smile: there's internal pullups in the arduino, just write the pin high, set it as input and check for low :slight_smile:

Thanks a lot for the schematic! I'm definitely going to bookmark that.

To use the internal pull-up resistors, make sure you set up the port pin as input first, and then set it high, like so:

pinMode(2, INPUT); // set port pin 2 as input
digitalWrite(2, HIGH); // turn on internal pull-up resistor