PWM and ethernet shield.

I'm a bit confused by some behaviour I'm seeing. I have an common anode RGB LED connected to pins 9, 10 and 11 + 5v. I've been playing with controlling the colours etc and that's been great. What's confusing me is that I can turn off all 3 colours in the setup function but, if I do this when using an ethernet shield then calling this line in the loop function...

Client client = server.available();

...causes the led attached to pin 11 to light up.

Can anyone shed any light on what is going on here please?


The ethernet shield uses pins 10, 11, 12, 13 according to the manual.

So pin 11 is unavailable for PWM

Oops - that's fairly clearly documented...sorry.

I guess that means that if I want pwm with ethernet I need to do it in the software myself or get some other bit of kit to handle it?

Pins 3, 5, 6, and 9 also have pwm.

Pins 3, 5, 6, and 9 also have pwm.

That's great! You've made my morning.