Is my Arduino Yun's Onboard LED (L13) really PWM?

I’m a newbie to Arduino so this may be easily explainable, but running the Basics\Fade Sketch with the led constant set to 13 (Not 9), I get a recurring fading onboard LED as if PIN13 was a PWM output.
According to the board/literature, PIN13 is supposed to be just a standard digital i.o!

Can someone run “fade” with “int led = 13;” and see if they get the same results as me?

The Yun uses a '32U4 processor. The list of pins mentioned on the analogwrite() reference page is for '328 and '168 processors. For the 32U4, the valid PWM pins are 3, 5, 6, 10, 11 and 13. These are the same pins as on a Leonardo.

The analogwrite() reference page mentions the differences between several processors, it would be nice if it specifically mentioned those boards that use a '32U4 processor.

Thanks ShapeShifter, it had to be something simple like that.

When I bought the Yun it was described as UNO compatible, so that isn't quite true. The Yun's header connections that are marked with the PWM '-' sign are:-


9- is wrongly marked too. I guess the manufacturers of the Yun were too lazy to print off a new run of headers. Hopefully the other connections are correctly marked?

Interesting... I just looked at one of my Yuns and the headers are indeed marked the same as an Uno. But the Yun is much more like a Leonardo (which shares the 32U4 processor) than an Uno (which has a 328P processor.)

Note the labeling on the Leonardo:

My guess? With all of the extra Linux and networking stuff on the Yun, they didn't have room to put silkscreen on the board like on the Leonardo. So instead, they used the silkscreened headers from an Uno, even though there are a few differences? At least the pin numbers are right. ;)

D13 is connected to processor pin PC7, which has a few alternate functions, one of which is timer 4 output compare A. So it most definitely can do PWM.

BenPhillimore: 9- is wrongly marked too.

I'm sorry, I neglected to include pin 9 in my previous list. D9 is processor pin PB5. which can also be timer 1 output compare B, or timer 4 output compare B. So it also can do PWM, with a choice of two different timers.

It also looks like D12 can technically output PWM, but it appears to be strictly the inverse of the PWM on pin D6, so it's not all that useful. Probably why they didn't bother to indicate it as such.