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Welcome to the Guzunty Pi wiki!
The purpose of the Guzunty Pi input/output expander is two-fold:-
- Protect the delicate GPIO pins of the Raspberry Pi computer and
- Provide up to a net 25 additional input/output expansion lines.
The objective is for it to do this at very low cost. To keep the cost down, it is designed for easy home assembly. Anyone should be able to build one of these for only about 15 bucks!
However, the Guzunty is much more than a simple I/O expander. It is programmable, so you can use it to do things that conventional line driver IC's could not achieve. Things which would otherwise use a lot of CPU time.
At the heart of the Guzunty is a Xilinx XC9500XL Complex Programmable Logic Device.
A CPLD is like having several large breadboards laid out on your desk, full of every combination of logic devices you are ever going to need. It is waiting for you to tell it what you want it to do. It doesn't need a host of jumper wires, it can be reprogrammed again and again (even at runtime), and it fits in a couple square centimeters.
A CPLD program is often referred to as a ‘core’ to distinguish it from a traditional computer program. Cores can do things thousands of times faster than an equivalent computer program.
This community has been started for Guzunty builders so that users can team up to create and share cores that work with the Raspberry Pi. Thus, the chances are that you'll find a core that does what you want right here. You won't need to learn how to create your own cores unless you want to.