I finally got around to having some fun with the ATTiny85 and created a simple little solar tracker. I call it the TinyTracker The ATTiny uses it’s A/D converters to measure the voltage from a couple green leds used as light sensors, and uses its pwm pins for controlling an H-bridge to drive a motor. The voltage regulator takes up to 36v so motor power can be used for logic too, i.e. just one power connection. I made sure to use at least 105C rated capacitors so hopefully it will be OK in the summer sun. What’s really amazing is that I designed the board in a day, wrote the program in an hour or less, and the darned thing worked the first time I tried it!
I’ve trimmed the vane down a bit from the picture (it’s just made from cardboard). It’s a bit optional really, but it does improve accuracy. I’m still trying to decide what the best enclosure is. So far it’s a dummy security camera dome sealed on top of a double-gang outdoor PVC junction box, but sideways in a clear jar with a lid for the base works pretty good too.
I’m selling assembled boards as well as linear actuators at my website http://homecsp.com/store/product.php?id_product=36 in case anyone is interested.