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geekhack Projects => Making Stuff Together! => Topic started by: cu99 on Fri, 19 March 2021, 15:39:51

Title: Learning from the UnSplit Keyboard
Post by: cu99 on Fri, 19 March 2021, 15:39:51

I'm new to PCB design and I want to start by learning from a real world project. Here's the interesting project I want to learn from https://github.com/swiftrax/UnSplit

# HSB
The HSB is connected to a 10k resistor, and to the ground. Why do we need an HSB and a RESET pin?

# ESD protection
There are other boards come with an ESD protection. But this board uses a fuse. When do we need an ESD protection chip?

# JTAG
Does it make sense to add a JTAG for easier flashing?

# BOM - Choosing the right Resonator
The post https://www.partsnotincluded.com/sparkfun-pro-micro-with-usb-a/ mentioned the proper load capacitance should be 16pF.
The UnSplit repo lists CSTNE16M0V530000R0, which is 15pF. I've seen other pro micro boards uses 12pF or 9pF.
How should one choose the right resonator?


Thank you for your time!