Timing with Fez Panda?

NETMF & Gadgeteer
1

I’m building a hi-tech outdoor animal waterer. The basic gist is will have 3 main operating modes based on a couple temperature sensors: Above 35F = off, between -10F and 35F = cycle heater as needed to keep the water at >34F, and below -10F, keep the water >34F, but twice a day spike the temperature up to 60F to defrost any ice off the top of the unit.

I’ve got a Panda II, but I’d like to keep it for experimentation, and buy an old-school Panda for $15 to keep permanently in the waterer.

I’ve never used an old-school Panda, but see that it lacks the real-time-clock of the Panda II. I’m not 100% sure what functionality that means the Panda lacks.

Is there a workable way to time a (rough) 12 hour time span with the old-school Panda to get the needed functionality of doing a defrost cycle twice a day? (No need to be precise.)

I just want to make sure that I don’t save $20 over getting another Panda II, and end up with a unit that won’t do what I need it to do for my project.

2

Without an RTC, that will be challenging. An external RTC is not that expensive (< $5). Take a look at the Rhino - they do have RTC and are only $5 more. They also have a spot for WIZ811MJ ethernet, which you can get for $20-25.

[edit] You could roughly estimate sunrise and sunset with a photocell. Would take some trial and error to get the right light value to trigger an action. In the middle of winter, the days are pretty short.

3

This topic has been dicussed before, search the forums

eg.

http://www.tinyclr.com/forum/2/4341/

4

If you just need to fire an event every 12 hours, you don’t need an RTC imo. The internal clock can be used for that.