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Made my first SMD PCB: A 1-to-8 USB switch with optocouplers to mimic power button presses 1
Made my first SMD PCB: A 1-to-8 USB switch with optocouplers to mimic power button presses
Made my first SMD PCB: A 1-to-8 USB switch with optocouplers to mimic power button presses
Hey all, thought I’d share my first successful adventure in SMD soldering: A 1-to-8 USB switch with accompanying optocoupler-based power button control. This was part of a [custom RPi4 based KVM setup to control a computing cluster](https://www.reddit.com/r/homelab/comments/1303d46/recently_upgraded_my_homelabawayfromhome_with_a/) I built that is stored in a different state. The USB switch is based around the MAX4999 chip, and since it was only available in a QFN package I figured “Screw it, water wings off, we are diving into SMD design.” USB destination selection is facilitated through MCP23017 I2C controlled IO expansion chip, and because I had a bunch of spare outputs I decided to add accompanying optocouplers for each USB connection. These optos let me mimic power button presses on the computers by patching into the normal motherboard connection through a little Y-splitter, that way I can remotely force computers to hard boot and turn back on in case one of them freezes. The RPi4 also can talk to a Pi Pico which acts as an emulated HID keyboard, so I can pipe keyboard presses to any computer. Turns out I didn’t need any of the external power supply stuff, but oh well. I designed the board in KiCad, ordered the PCB from JLCPCB, and used a [DIY reflow oven made from a toaster oven](https://www.reddit.com/r/diyelectronics/comments/yuhmf2/bought_the_oven_15_years_back_at_a_garage/). Happy to answer any questions or share the schematic if anyone is interested!