CH423S IO expansion chip application

* This project is used to verify the solution verification board design of [LiChuang Mall](https://www.szlcsc.com/) Interface - I/O Expander CH423S ([Product Number: C111663](https://item.szlcsc.com/112891.html)).
* **Also** used to verify the solution verification board of [LiChuang Mall](https://www.szlcsc.com/) White Dot Matrix ([Product Number: C225986](https://item.szlcsc.com/226236.html)).
* This project is a sample project of [LiChuang EDA Open Source Hardware Platform](https://oshwhub.com/) [Solution Verification Module Collection Order](https://oshwhub.com/rewards/f4bbab6365034e80aadb8f8ebf77c846).

CH423 is a universal remote I/O expansion chip with a two-wire serial interface. CH423 provides 8 bidirectional input and output pins and 16 general output pins, and supports input level change interrupts; CH423 has a built-in current drive circuit, which can statically drive 24 LED light-emitting tubes or dynamically drive 128 LEDs (equivalent to 16 digital tubes); CH423 exchanges data with microcontrollers through a 2-wire serial interface.
Combined with dot matrix to form an 8*16 dot matrix module, the iic interface greatly saves the io pins of the microcontroller.

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