I found your article when researching the datapoint API (although I started from http://spectrum.ieee.org/geek-life/hands-on/building-a-bicycle-barometer).
I just thought I'd mention I think the time formatting in your example could be simplified. I went with :
sprintf("%02d" ,($timeNum / 60)) . ":00";
There is no need to protect against dividing by zero - its dividing by 60 :-)
All the best,