// HACKER NEWS — CYBERSECURITY
Show HN: PaperMono, e-ink fridge magnet shopping list with mobile web page
Firmware for the M5Stack PaperMono
e-paper device. It turns the device into a household shopping list that lives on
the fridge and stays in sync with a phone web app.
The PaperMono is an ESP32-S3 with a 3.97" 480×800 e-paper touchscreen. This
project is a complete, working app for it that's small enough to read: about
2,400 lines of C++. You can use it as a shopping list, or as a starting point
for your own PaperMono firmware.
The device shows the list grouped by aisle, in the order you walk the shop. Tap
an item to tick it off, or add one with the on-screen keyboard. Everyone else
adds things from their phone.
A small server in between stores the list. It remembers which aisle every item
belongs to and can optionally sort brand-new items into the right aisle with
Claude.
Open http://:8000/ on your phone, tap Aisles, and add your shop's
aisles in the order you walk them. See docs/server.md for
systemd and Docker deployment and for turning on auto-sorting.
You need PlatformIO and a PaperMono connected over USB-C.
Back up your device's flash before the first flash. It holds that unit's
factory calibration data. docs/firmware.md covers the backup,
download mode and flashing from a browser.
A personal project, running on one device at home. It works, but it isn't a
product. There's no on-device Wi-Fi setup (credentials are compiled in), no
authentication on the server (keep it on your LAN or behind an authenticating
reverse proxy), and only the PaperMono C153 has been tested. See
known limitations.
Built by Seamus Cawley, who builds Bronto, the logging and
observability platform, by day.
The firmware's board support, e-paper and touch drivers, keyboard layout and
widget style are adapted from MonoMesh by
andrecolz, an independent Meshtastic-compatible firmware for the same hardware.
docs/design-notes.md lists exactly what was
reused.