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

Show HN: PaperMono, e-ink fridge magnet shopping list with mobile web page(github.com)

64 points by seamus_c 5 hours ago | 20 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

cush 7 minutes ago |

This would be cool if you could write on it with a stylus. I can’t imagine typing on my fridge - too clunky

schnevets 48 minutes ago |

Pretty cool! I remembered having a brainstorming session with co-workers about all the cool use-cases for e-ink displays over a decade ago. A product precisely like this was definitely mentioned, as was conference room displays, data center cage information, Kanban-style sticky notes in manufacturing, dynamic game pieces, among others. You'd think simple displays like the PaperMono would be as cheap as bluetooth speakers by now, but I know there are some major patent restrictions.

I can tell you this conversation happened over a decade ago because LCD Touchscreens were still more expensive than e-ink at the time.

lp92 36 minutes ago | |

Game pieces with integrated eink to track health/stats and other game relevent metrics would be an interesting application.

seamus_c 29 minutes ago | | |

That's a cool idea! There are small 1.54" e-ink screens, I wonder would it be possible to add an NFC chip and have them completely passive? (i.e. powered from the writer)

edoceo 1 hour ago |

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?

utopiah 21 minutes ago | |

I'd check https://github.com/Josh-writes/microslate-firmware/ for the xteink as it is less focused on only reading, but keep in mind it's a screen only, so not touch. Buttons though are pretty good so enough for tick items on a list IMHO.

seamus_c 1 hour ago | |

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)

hn1rig3rak 2 hours ago |

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 2 hours ago | |

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

drumhead 54 minutes ago |

This is giving me Juicero vibes.

nouveaux 48 minutes ago | |

I think open source code would sit in the opposite end of the spectrum to Juicero.

lucasrufkahr 3 hours ago |

Hold on babe I gotta charge my fridge magnet…

Jokes aside this is cool

jameshart 44 minutes ago | |

Think about e-ink is it stays readable even when the charge runs out.

ex1fm3ta 2 hours ago |

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 ?

hansihe 46 minutes ago | |

There is exactly one manufacturer of large EPDs, E Ink Corporation.

A few have tried to compete over the years, none have really managed to ramp up production and compete from my understanding. I believe there are some chinese firms making smaller panels now, mainly used in electronic shelf labels for stores.

From my understanding most of the patents for the foundational tech have expired at this point. I believe the panels are just generally very difficult to make, with difficulty ramping up further as panel size goes up, presumably the yield is fairly low.

seamus_c 55 minutes ago | |

That was part of the motivation here: If I can think it up, can AI actually build it, even when it's outside my day-to-day experience? (and can it do it without frying the hardware somehow)

Palomides 1 hour ago | |

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

j45 1 hour ago | |

The last time I checked, patents.

otherme123 23 minutes ago | | |

Key eink patents are expired since c. 2017. But they bought potential competitors and keep innovating (and patenting), so the monopoly stays strong. If someone entered the market right now, with 2000 eink tech, and pricing at very low margin prices, they will go bankrupt: would you buy a 20" screen, no touch, ~70 ppp, refresh around 2 seconds for maybe $300? Also, patents might have expired, but key tech, such as precise micro-sphere manufacturing, is not under patent protection, but under trade secrecy: on top of old tech, it would be unreliable. Some like Zhiwei specialize in epaper for tags using old tech, but only for b2b and barely below Eink prices.

Competition explores completely different technologies: Daylight DC-1, Reinkstone, ChLCD e.g. from Iris... but either the tech isn't good enough to generalize or be cheap (the later), or the niche economics don't allow the inventors to keep investing (the two first).

jader201 2 hours ago |

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