Since today is Pi-day and I am learning OLED with Hexiwear.
I try to use Hexiwear to calculate Pi.
If you search Pi at WIKI
You can see a formula
Below is I use Nilakantha series to calculate Pi and show it on Hexiwear.
when I edit this project I found I am mistake. It's Nilakantha series not Gregory–Leibniz series. But I am lazy upload video again. So....