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Timing with Fez Panda?


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.


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.


This topic has been dicussed before, search the forums



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.