single pulse every morning from solar panel

[djacobow]

I'm a bit embarrassed to be asking this in the beginners forum, but my analog fu is pretty weak.

I have an RPi that I am powering from solar + battery remotely. The unit does not need to run at night. To reduce cycling of the battery (and to allow it to be smaller), I'd like to shut down the pi at night.

I need a circuit that can do two things:

1. generate a signal that I can send to the gpio when the voltage from the panel (it's a 6V panel) goes below a certain value. I'll use this signal to initiate a clean shutdown
2. generate a pulse when the panel goes above a certain volate. Preferably, it would only do so if the panel was above that voltage for a certain amount of time, and it would not do so repeatedly within a short period, say 10 minutes. Ideally, one pulse in the morning. This pulse would reset the pi and cause it to boot.

I can do this with another micro, but thought it would be nice to see if I could pull it off with a few transistors, maybe a 555 or two. Is there an obvious, simple solution?

[tautech]

Something like a CMOS Micropower Over/Under Voltage Detector like Intersil's ICL7665 is what I've stocked up on for H/L voltages monitoring use. 2 monitoring circuits in the package and logic level outputs. Available in DIP 8 and SOIC 8.

[tautech]

Thinking about it some more you might only need one part of the package if you get the user definable hysteresis as you want it. Get both the Intersil and Maxim datasheets.....Maxim attached FYI, use Fig 5.

[djacobow]

This was a one-off for a quick hack project, so I was hoping to use stuff I had around rather than a special purpose chip. In the end I used an attiny 84  because I had a tube of them laying about.

With the adc's I could implement whatever hysteresis function I wanted.

One more opportunity to improve my analog skills passed up....

[Zero999]

This was a one-off for a quick hack project, so I was hoping to use stuff I had around rather than a special purpose chip. In the end I used an attiny 84  because I had a tube of them laying about.

With the adc's I could implement whatever hysteresis function I wanted.

One more opportunity to improve my analog skills passed up....

That's the best solution. You also can modify  the software to compensate for things such as clouds and a solar eclipse.

Analogue skills are still very important these days but not for this sort of thing.