TRMNL Meeting Room Display: The Honest Guide · Lobby

Most posts about meeting room displays start with the software. We are going to start with the hardware, because that is where most of the cost, complexity and lock-in live.

TRMNL is an open-source, battery-powered, 7.5 inch e-ink display. It is the hardware Lobby ships on. It is also, on its own, one of the most interesting pieces of office signage hardware to land in the last few years, and almost no one outside of niche maker communities is talking about it. This post is the honest tour.

What TRMNL is, in 60 seconds

TRMNL is a small e-ink dashboard built around an ESP32 board, a 7.5 inch 800 by 480 monochrome e-paper screen, and a 2,000 mAh battery. It runs open-source firmware (the source is on GitHub at github.com/usetrmnl) and connects to WiFi to fetch screen images from whatever server you point it at. A finished device runs about USD 129 to USD 199 depending on bundle. There is also a USD 45 DIY kit through Seeed Studio if you want to assemble one yourself.

The screen consumes effectively zero power between refreshes, which is what gets you the "up to 12 months on a charge" battery life that competitors with LCD displays cannot touch.

Why this matters for meeting rooms

Most proprietary meeting room displays are built on a similar idea (e-ink, low power, WiFi sync). Joan was the first at real scale. The problem is that Joan, Robin and friends sell hardware that is locked to their software. If you buy a Joan 6, you cannot run Robin on it. You cannot run a Lobby image on it. You cannot run a Home Assistant dashboard on it on weekends. That is fine if you are happy in the walled garden. It is annoying if you are not.

TRMNL inverts that. You buy the hardware once and choose what runs on it. For a meeting room display, that means:

Lobby today, something else tomorrow if you change your mind.
Self-hosted firmware updates if your security team requires them.
Repurposing the display as a quiet office sign, a weather panel, or a status board outside business hours.
No vendor lock-in on the physical device.

What TRMNL does well as a room display

The things that make TRMNL a strong room display are mostly things you would expect from any e-ink panel, plus a few that are particular to this device.

Battery life. 8 to 12 months on a single charge in typical office use, depending on refresh frequency. Charge once a year. Done.
Readability. 800 by 480 monochrome e-ink is readable from about 5 metres at door height. No glare. No backlight to compete with overhead lights.
Silent. No fan, no hum, no light.
Wall mount that does not require a drilled hole. Lobby ships a magnetic mount that works on any surface that takes adhesive. TRMNL on its own works the same way.
Quiet WiFi behaviour. The device wakes, syncs, sleeps. It does not chatter on the network. The IT security team likes this.

What TRMNL does not do

An honest list, because this hardware is good but not magic.

Touch. The 7.5 inch panel is not touch. If you want a "tap to check in" interaction at the display, you need either a paired QR code that opens a check-in page on a phone, or a separate tap accessory. Lobby uses the QR approach because it works in every office and needs no extra hardware.
Fast refresh. E-ink updates take a second or two. For a room display this is fine. For an interactive UI it would not be.
Colour. Monochrome. You get black, white, and a few greys.
PoE. No power over Ethernet. The device runs on battery, with USB-C charging.
Native MDM. If your organisation requires Jamf or Intune control of every endpoint, TRMNL does not enrol. You control it through firmware configuration and WiFi credentials.

The realistic cost per room

For a single meeting room, with the platform that runs on top.

Hardware. USD 129 to USD 199 per display, one-off. Or USD 45 if you buy the DIY kit and assemble it yourself.
Mount. Included with the official device. Around USD 8 to USD 12 if you buy aftermarket.
Software (Lobby). Free for up to 3 displays. USD 30 per month flat for unlimited rooms on the paid plan. Both listed on our pricing page.
Setup time. Around 10 minutes per display for the WiFi pairing, then a couple of minutes per room to connect calendars.

Compared with Joan 6 (around USD 600 per display plus USD 8 to USD 18 per room per month on top), TRMNL plus Lobby comes in at roughly a third of the five-year total cost for a 10-room office. The numbers move around with discounting and currency, but the order of magnitude is consistent. The pricing comparison post goes through the worked example.

The "can I just run my own software on it" question

Yes. TRMNL is BYOD-firmware. If you have an internal team that wants to render dashboards or signage with your own server, you can. The firmware accepts a target URL and refresh interval. The display polls that URL on its schedule and renders whatever PNG comes back. That is the whole protocol.

This is also why Lobby works on it. Lobby's job is to take your Google Calendar or M365 room calendar, render a clean status image, and serve it to the TRMNL on schedule. Nothing exotic. The device does not know it is in a meeting room. It just renders the image.

Three things we wish we had known earlier

Pick the official bundle if you are doing more than two rooms. The DIY kit is fun, but assembly takes about 20 minutes per device and the cost difference for ten rooms is not worth the soldering iron.
Place it at eye level, not head height. Slightly below eye level reads better when you walk up to the door. The mount allows for it.
Use a longer refresh interval on quiet days. The default ten-minute refresh is fine in busy offices. For a small office with five rooms, fifteen or twenty minutes will give you two years of battery instead of one without anyone noticing the lag.

Who should not use TRMNL

If any of these are true, TRMNL is not your best option.

You need full Jamf or Intune device management, with screen capture and remote wipe.
You want a 13 inch display for very long room names or rich content.
You want colour.
You need PoE because WiFi is unavailable in the meeting room corridor.

For everyone else, this is the best price-to-honesty ratio we have seen in office signage hardware in years. That is partly why we built Lobby around it.

TL;DR

TRMNL is open-source e-ink hardware that makes a great meeting room display. It is 7.5 inches, monochrome, battery-powered (8 to 12 months per charge), and costs USD 129 to USD 199 per display. No touch, no colour, no PoE, and no MDM. Pair it with Lobby (free up to 3 displays, USD 30 per month unlimited after) to get a complete room display setup at roughly a third of the cost of Joan or Robin. The fact that the hardware is not locked to one piece of software is the main reason we built on it.

Using a TRMNL as a Meeting Room Display: What Works, What Doesn't, and What It Costs