[ELECTRON] Arduino project help.

[Andrew Back]

On (22:31 25/01/11), Gordon JC Pearce wrote:

> The thing that switches the reading between positive and negative looks
> a bit hairy.  Have you considered just using a single PWM output, and
> making it "idle" at 127?

Hairy how so? 

Well, the problem is that the meter I have is 5-0-5v, so I need to swap the
polarity of the PWM drive depending on whether mains is >50Hz or <50Hz.

The problem isn't limited to the transition above/below 50Hz either.
 
> I'd also be slightly wary of counting microseconds like that; I'd be
> more inclined to take a moving average of the last ten readings every
> time the comparator interrupt fires.

Not sure I understand the concern... You might have to be explicit - I'm not
a coder and so I'm not clear as to why this method is bad. 

As to a sliding average, the problem is that these periodic hugely out
readings would still throw the product out somewhat.

Cheers,

Andrew

-- 
Andrew Back
a at smokebelch.org