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Show HN: PaperMono, e-ink fridge magnet shopping list with mobile web page

39 points seamus_c 4 hours ago 9 comments

Fridge magnet shopping list on an M5Stack PaperMono (ESP32-S3, e-ink touchscreen), synced with a phone web app over Wi-Fi. Works offline, ~2,400 lines of C++.

This is a great wee device! BLE, Wi-Fi and LoRa on one board makes it flexible for way more than a shopping list, this is just what I built first. This firmware only uses Wi-Fi.

Fully vibe-coded with Claude Code, I didn't hand-write this. I wanted to see how Claude would get on with building something useful for a new hardware device.

As it's stuck to the fridge it's easy for the family to use, and it's already being used day to day which I'll admit is a first for a home built project like this

lucasrufkahr 2 hours ago | parent

Hold on babe I gotta charge my fridge magnet…

Jokes aside this is cool

jader201 1 hour ago | parent

At first I thought “that’s a very specific shopping list for fridge magnets”. :)

hn1rig3rak 1 hour ago | parent

Curious what you landed on for refresh, full flash or partial? Ticking off items one by one is exactly where partial update artifacts pile up on these panels.

seamus_c 1 hour ago | parent

I stuck with the recommended full refresh every 15 interactions and partial otherwise. There's also a full refresh when moving from the settings screen back to the main list. Honestly though it probably makes sense to only do a full refresh when unticking (which is rare) or changing screens. The typical use cases are (1) glancing at the screen to make sure something is one the list and (2) ticking things off as they go into the basket. Neither really require a full refresh imho. Some ghosting is acceptable in general use I think

ex1fm3ta 1 hour ago | parent

Project like this make me excited with AI. You can pretty much custom firmware, tailored for your specific needs. Thanks for this repo. Quick question to the community : why does nobody makes afordable huge e-ink displays ?

j45 51 minutes ago | parent

The last time I checked, patents.

Palomides 38 minutes ago | parent

there's no secret, they're just expensive to manufacture

edoceo 56 minutes ago | parent

I was just working on something similar. Was about to buy the xteink for my display. You've accelerated my progress. How's the battery life?

seamus_c 50 minutes ago | parent

Honestly it's pretty good, but it's too new to give you an actual number. I haven't had to think about it so far. As a LoRa Meshtastic node the device ran for days and still had plenty of battery.

In normal operation battery life is by how often you do a refresh, the rest of the time it's in deep sleep. I think for this application I could build in a refresh schedule tied to when the house is active (mornings, evenings, weekends) to reduce the number of refreshes. It syncs on touch if it hasn't synced in the last 5 minutes (and there's a button for when your feeling impatient)