Pin 13 - the LED. Stuck with trying to use it.

Other Hardware Motors, Mechanics, Power and CNC
1

Folks,

I have bought this relay:

http://www.ebay.com.au/itm/200939860395?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

I can easily connect it to other pins and turn it on and off with the Arduino.

Because (typically) there aren't enough I/O pins, I am looking for options.

As pin 13 drives the LED, and is available for connection I thought I would give it a go.

Alas it doesn't seem to want to work.

When I try to drive the relay it (the relay) clicks and clicks.

I appreciate that the LED has a resistor as well. So the question is:
Is it: Pin, Resistor, LED, Ground
Or: Pin, LED, Resistor, Ground

Thanks in advance.

2

Pin 13 should function OK - it doesn't matter which order the LED and resistor are wired,
they are in series, and the LED doesn't take much current.

Note that on reset pin13 will toggle to flash the LED as part of the bootloader initialization
sequence, this is hardwired so its probably a bad choice.

Perhaps your relay switching was causing a reset?