I decided to make a cool gift for my wife anniversary so I designed a PCB jewel. She loves butterflies so I tried to make her one.
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It uses a standard 3V CR1220 battery in order to blink 12 LEDs. The micro-controller is an ATTiny85-20MU that drives directly the LED’s. The first iteration used 3 AG1 batteries but I switched to the more covenant CR1220.
I need a voltage over 2.2V in order to light the LED’s but I don’t power on all LED’s at once, so I don’t need a driver for them. I can easily get 20mA from the digital pins of the ATTiny85.
Check the working video:
After looking through the projects of Gerben I learned that I can use the tristate input of the uC to mask the unwanted LEDs. Basically it divides the 3.3V voltage in two sub 2.2V that I need to light a LED. It was too much code to use the pinMode function of the Arduino so I put the needed DDRB register values in an array. Now I can do some nice rotating and bouncing effects - wrote some helper functions for them.
So I've updated the Github project files accordingly.
Thanks Gerben!
Very pretty.
Interesting way of placing the resistors in your schematic. I always have both the anodes and cathodes go through a resistor (and use halve the calculated resistor value).
Is it running stable without any capacitors?
strofo
Rebelj12a
Chris Hamilton
DIY GUY Chris
Vikas V
Thanks! Yes it's been running for several days now. I don't think I need the caps because I don't have any communication going on. It's just internal processing and I don't care about timing too much.