2-in-4-out USB switcher

I. Description:

A touch-sensitive USB switcher with dual Type-C inputs and four USB-A outputs.
It features two indicator lights to display the current input status in real time.
The power supply uses a CH213K ideal diode chip, which automatically selects the power input and provides reverse power supply.
The board thickness is 1.2mm.
The CH334R has a built-in crystal oscillator matching capacitor, eliminating the need for additional soldering; therefore, the two crystal oscillator matching capacitors on the PCB do not require soldering.

  II. Function Introduction: This device
allows the use of a single set of USB devices such as keyboards, mice, flash drives, and printers between two computers, enabling one-button switching without the need to plug and unplug data cables.
III. Working Principle:

The CH440R is a QPDT analog switch chip containing four single-pole double-throw (SPDT) 2-to-1 switches.

 
 

The CH334R is a 4-port USB hub controller chip compliant with the USB 2.0 protocol, supporting high-performance MTT mode, which is superior to USB hub chips that only support STT. It features an industrial-grade design with a simplified peripheral circuitry.
The TTP223 provides one touch signal input, and its output pin connects to the IN pin of the CH440R to provide a level signal. Touch sensitivity can be adjusted by changing the capacitor value to prevent accidental touches.
The CH213K ideal diode chip has a voltage drop significantly lower than commonly used Schottky diodes and provides some over-temperature, over-current/current limiting, and short-circuit protection.

 
IV. Housing Design:
The housing has been verified.
Hole tolerances have been verified.
It adopts a top and bottom cover design with pre-drilled holes for M3 T-shaped thermoforming nuts for easy assembly and disassembly.
The top cover has pre-drilled holes for 2mm acrylic light guide pillars; the light guide pillars cost as low as 1 RMB/meter, achieving good light guiding effects at low cost.
3D printed using PLA material, no support required.
The bottom can be custom-engraved. Modify the bottom using the STEP file (attached).
 
V. Reference Project:
https://oshwhub.com/alphacc/alpha-ch440_zj-c00
Thanks to the above contributors for their open-source contributions
 
. VI. Conclusion:
There are still areas for optimization and improvement in the project. The wiring and layout have room for improvement. The USB differential cables only have simple length equalization and lack ESD protection components. These are areas for optimization, but my time is limited.
The four 100uf tantalum capacitors are relatively expensive; a package compatible with 10uf capacitors could be added, and soldering could be done according to requirements. Soldering four tantalum capacitors can barely power an external hard drive, but overall, it's not recommended to power an external hard drive (to prevent damage due to insufficient power). For daily use, soldering one or two 100uf capacitors is sufficient.
As of March 28th, I have been using it stably for nearly three months, occasionally encountering recognition issues, which are resolved by unplugging and replugging (possibly related to the quality of my data cable?). If you have any other questions, please provide feedback after you recreate the project.
Note: Based on my experience over the past six months, I've occasionally encountered situations where some USB devices might fail to connect during switching, even without power. Perfectionists should exercise caution when replicating this solution or consider alternative options. I will also update the 4-in-4-out CH9374B solution later (power off during switching and supports hotkeys and other switching methods), which is more perfect than the current version. A CH645W solution is also planned, but information is currently limited; I will continue to follow up.
I hope to see your submissions in the comments section! Thank you!
A 4-in-4-out switcher for CH3974B should be updated later. Those who need 4-in-4-out switches can look forward to it.
 
Update Log:
2024/03/28 Uploaded project and model files.
2024/03/29 Uploaded BOM to attachment; please refer to the dimensions in the table to purchase springs, screws, and other accessories.
2024/04/25 Inquired with wch technical support; the CH334R already has a built-in crystal matching capacitor, so no additional soldering is needed. Therefore, the two crystal matching capacitors on the PCB do not need to be soldered. Crystal oscillator parameters are selectable: 12M, 12-20pF, 20ppm. Does the CH334R crystal oscillator require a matching capacitor? - Qinheng Microelectronics Community (wch.cn)
updated text description on 2024/8/13.