If you can’t find it in docs then just ask here and we will help
[quote]1. What is the maximum sink/source current for an general purpose I/O pin in output mode?
4mA. You can go a but higher but then the voltages drop.
[quote]2. Can I just hook up a CR2032 lithium button cell to the RTC VBAT pin?
Yes, any 3V battery will work
[quote]3. Are there any special considerations that need to be taken to hook up a piezo to the IO10/Piezo pin?
No but it is always good practice to add small resistor.
Good one! We have just added support to alarm so you will eb able to use this pin in next release. This pin goes high when the alarm you have set have fired. The special thing about this and RTC is that it runs even if the board si powered off (using the 3V battery)
All your questions are valid, clear and to the point. Thanks for reading the docs before posting questions