I’ve been thinking a bit about how overkill a full Arduino is for Shutterfingers, and feeling a bit sheepish about how lazy I am about learning to use some other microcontroller. Then I found this guide talking about the ATtiny85:
If you’re just blinking a few LEDs, and reading a single sensor, you can get the job done smaller and cheaper using a simple IC, like the ATtiny85.
Using it requires a programmer socket and actually mounting the IC to a PCB, but it seems to have enough going on to be useful:
That looks like there are:
- 5 GPIOs
- 3 analog inputs
- 2 PWM outputs
It’s programmed with the Arduino IDE, but it’s not a fully capable Arduino and many (most?) libraries don’t work with it. At least there’s a servo library written specifically for it.
I think there’s enough room on this tiny board for the ATtiny85, some pull-up resistors for the signal input (2 pins), the servo signal out (1 pin), and status LED (1 pin). I’d have one more pin left over for something else. Power from this LiPo charger/booster and battery.
If I were actually interested in manufacturing the product, the less expensive part would be better, though the battery and charging components seem to be the biggest costs.
On the other hand, Shutterfingers could be expanded to do more with the larger, more capable Arduino.
Update: and then I found the Digispark board. It packs an Attiny85, USB controller, and power regulator onto a 7.5mm x 10mm (approx) PCB, including the USB plug!