MCU Solar Landscape lights?

[HarveyH42]

I've had this in my head for some time now, but still don't know enough to give it a try yet, but would like to get started. Path lights are kind of boring, and have been wanting to make the pulse, fade, blink, flash, color change, and so many other things.

A ATTiny13L will work at 1.8 volts (even less). From what I've been led to believe the analog comparator only works on voltage less than the chip's supply. The solar panel must put out more then the battery voltage. I'd like to use the solar panel to detect night fall, but not sure how to do it without frying the MCU, or wasting a lot of charging current through a resistor. Should mention that I have never messed with the analog comparitor done anything with ADC. Most of the documentation goes in to more advanced signals. Guessing this is stupid simple and not worth putting into appnotes.

Anyway, I have a bunch of 6 volt open, 4.5 volts under load, 50 mA solar panels. Should charge 3.6 volts worth of AAs. Not sure if the MCU needs a regulator, or what to use. I don't think I have anything smaller then a 78L05, maybe some zeners someplace. Really want to keep it cheap and minimal.

Just figured I throw this out for some suggestions. Might be a fun beginner project for somebody else as well.

 

[things]

wouldn't it just be easyer to use colour changing led's.(if you want to use your technique don't let me put you off

 

[Sceadwian]

I have one of those sitting on my desk, about as cheap as you can get them and it has a CDS cell, for detecting day/night using a solar cell to detect daytime isn't a good idea because it will stop producing usable energy while there's still plenty of light. CDS cells are trivial to interface to a micro controller, you just need a single additional resistor to bias it at whatever light level you want and you can feed it directly to a digital I/O line.