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The World's Smallest "Organic" Data Center?
It sounds like a joke, but it’s a fully functional HTTP server. It runs HTML, CSS and JavaScript, it has its own power source, and it fits inside a standard walnut shell. I recently finished a build using the Seeed Studio XIAO ESP32-C6, a recycled vape battery, and a couple of power optimizations to extend battery life.
Watch the full build breakdown here
The Components
To fit a computer inside a shell this small, I needed the smallest form factor available that still supported modern WiFi standards.
- microcontroller: [Seeed Studio XIAO ESP32-C6](https://www.seeedstudio.com/xiao-esp32c6-p-5884.html) (RISC-V, WiFi 6, low power).
- battery: A 3.7V LiPo battery salvaged from a disposable vape.
- chassis: A walnut (grocery store grade).
- mechanism: 4x Neodymium magnets and a micro slide switch. I carved out the shell using a Dremel, carefully drilling recesses for the magnets. The magnets are cool - they allow the shell to snap together with a satisfying *click* and hold the "server rack" closed while allowing access for USB-C charging.
Power Optimization
1. Underclocking The C6 is capable of 160MHz, but serving a simple HTML/JS payload doesn't require that horsepower. I dropped the CPU frequency to 80MHz to lower the active current draw.
2. Lowering WiFi Range I don't need this walnut to cover a stadium. I lowered the TX (transmission) power of the radio. This reduces the range to a personal "bubble, " but saves a massive amount of energy.
3. The Transceiver trick. WiFi requires the radio to wake up and send "Beacons" so your server can see the network. I configured the power management to turn off the transceiver completely between beacons. It wakes up, shouts 'Hey,I am a here!', handles any immediate requests, and instantly powers down the radio until the next beacon interval.
Custom board
Xiao is super small and tightly packed, but we can do better. We can get rid a couple of components like GPIO pins or USB (use external USB<->UART instead) etc.
I even designed this PCB based on a raw ESP32 module (the.gerber files and other resources are in the repository). I didn’t order it myself because the PCBA cost was over $160 + shipping 💀. If you win the lottery and decide to try it, let me know! 😁
Important note: I don’t guarantee that my PCB is correctly designed. I’m an amateur designer (to put it politely), so besides being ugly, it might simply not work. Please verify everything before printing!
⚠️ Safety DisclaimerWorking with lithium-polymer batteries reclaimed from vapes can be dangerous. Ensure you follow proper safety protocols, use a protection circuit (BMS), and never leave the device charging unattended.
Want to build one?
I've published the source code and the wiring diagram on GitHub. It’s a great weekend project if you have a steady hand for soldering and a Dremel(like) tool.
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