HN Explorer

Show HN: Sidebar – a private ESP32 intercom for five kids, no accounts (sundaradnus.ca)

16 points by nonstopnonsense ↗ HN
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.

7 comments

[ 2.0 ms ] story [ 20.7 ms ] thread
smalltorch
It's a really great idea! How much for all the parts?
[deleted]
(comment deleted)
xchip
You should play more with your kids before they grow old.
nonstopnonsense
Fair point and unsolicited parental advice. There is only so much a son or daughter wants to play with you. By the time they are 10, they have their social circle built up. You also want them to have a circle (na unsolicited advice from me), as you don't want them to grow up all alone with none but their parents.

To answer: Yes, I am trying as much as possible I can (and he can) with each other.

quickdeer
As a grandparent without your skills, I am impressed with the idea and how you included your son in the development. Especially useful for parents who (like you) wish to delay smartphone purchase for their kids. Is any of this patentable? Sell to a toy company for mass production?