maximum polling frequency?

I just got my Espruino and wanted to see if i can make a touch switch from it. I wrote a small program to read analog values of pin C7 (random choice here) ..
while it works fairly reliably when I touch the pin, i do this by setting up an interval to check the value every 200ms. I'm wondering what the resolution of the polling is. Can I poll every 100ms? every 10ms?

Hi MikeD,

The timer Espruino uses at the moment is the 32kHz RTC, so while theoretically you could do that, you're limited by the speed of execution. You can test with:

counter = 0;
var i = setInterval(function() { counter++; },10);
setInterval(function() { console.log(counter);counter=0; },1000);
// then...
changeInterval(i,5);
changeInterval(i,2);
changeInterval(i,1);
changeInterval(i,0.5);

and it'll show you how many times per second it's actually been able to manage.

At the moment you're limited to about 4.5kHz = 0.22ms for simple functions like that example. The more complicated the function the slower it is though.

By contrast, I just tried this on a PC and it can manage roughly 240Hz compared to Espruino's 4500Hz :)

so will a setInterval with a period of 20-25 work well ? I know on desktop, this will typically be fairly awful cause javascript has a poor resolution on most browsers. How would the espruino handle multiple intervals of such a short period?

It should handle it very well as long as your functions don't take too long to execute. The accuracy is good - but try it and see :)