Show HN: Sidebar – a private ESP32 intercom for five kids, no accounts

www.sundaradnus.ca

12 points by nonstopnonsense 1 day ago

Hello all - Inspired by many who build/assemble for their daughters/sons, I took cue and assembled a two-way communication between my son and his friends. Nothing spectacular. Just basic stuff to talk.

He is eleven and doesn't have a phone. I wanted him to talk to his friends without an account, a feed, or an algorithm in between, so I built five ESP32-S3 touchscreen units, one per kid. Tap a friend's name, their unit rings. Tap Everyone, they all ring.

Each unit dials outbound to a relay I run, so no house opens a port. Audio is uncompressed 16 kHz PCM in 20 ms frames, AES-256-GCM with a fresh key per call, over UDP with an encrypted-WebSocket fallback. To be precise: encrypted to my relay, not end-to-end. No rooms, no recordings, no free-text contacts; the roster lives in a server-side allow-list.

I'm a PM, engineer by degree but not by profession - let alone a firmware engineer. I assembled this with Claude as the engineering partner, which is why the write-up includes what went wrong: I shipped an OTA that boot-looped my son's board, and separately "diagnosed" a Cloudflare outage that didn't exist because I tested from the wrong vantage point. Echo is still unsolved.

The enclosure was designed in FreeCAD by my son (11); the STLs are in the repo.

It was a fun and exhilarating work for me and my son - like most of you would have experienced.

Looking forward for your responses/feedback.

smalltorch 15 hours ago

It's a really great idea! How much for all the parts?

  • nonstopnonsense 14 hours ago

    All the 6 boards with mic and speakers set me back by $250 Canadian. And the 3D prints are $17 a piece.

    • smalltorch 10 hours ago

      Very cool, I made a similar walkie talkie style program. https://gitlab.com/here_forawhile/terminalphone

      I didn't realize a esp could run the tor binaries. I may have to dive into seeing if I can get it running on one now!

      Cool project thanks for sharing.

      • nonstopnonsense 7 hours ago

        Nice! I'll check this over the weekend and see what I can borrow from Tor perspective. Thank you so much for sharing.