Mushroom MinderChamber Controller
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Open hardware
Chamber Controller
Watch the temperature and humidity in your fruiting chamber from anywhere — an open-hardware companion you build yourself, from about $25 of parts, in an afternoon.
What it does
Temperature & humidity
Continuous readings from an SHT4x sensor, uploaded once a minute. An SHT31 works too.
Live display, optional
Build it on a "Cheap Yellow Display" board and a 2.4" screen shows the current reading, refreshed every couple of seconds.
Setup from your phone
A new board puts up its own WiFi network. Join it, pick your network, paste a claim code — no laptop, no USB, nothing to compile.
Its own identity
Each board gets its own credential and can write to its own chamber and nowhere else. No shared key to leak.
Three boards, one firmware
A plain ESP32, an ESP32-CAM or a CYD all run the same build. Use whichever you have.
Nothing in it can hurt you
This build measures and reports; it does not switch anything on or off. That keeps it entirely on the safe side of the wall: 3.3V logic, powered from a USB charger, with no relays, no mains wiring and no high-current loads anywhere in it. An earlier version of this project did drive a fogger and a fan, which meant an AC circuit sitting next to standing water, a hardware watchdog and a timer circuit to cap the fogger's runtime. A sensor you can leave running unattended turned out to be worth far more than the automation was.
Free integration with Mushroom Minder
Generate a claim code in the app, then power up the board and give it the code through its setup page. From then on its readings sit right next to the grow run in that chamber:
- Live temperature and humidity charts in your dashboard.
- Email alerts when a chamber drifts out of range — or goes quiet, which usually means the power or the WiFi dropped.
- Included free on every plan — no add-on, no extra cost.
Build your own
Everything is open: the wiring, the firmware source and the build instructions are all on GitHub under an MIT license. The whole bill of materials:
| ESP32 board — or a "Cheap Yellow Display" for a screen | ~$6–$15 |
| SHT41/SHT45 temperature & humidity breakout | ~$5–$10 |
| Four jumper wires | ~$1 |
| USB power supply | ~$5 |
This is a DIY hardware project shared as-is, not a certified consumer appliance, so treat what it tells you as informational rather than something to bet a harvest on unchecked.
Get the parts list, wiring and source on GitHubQuestions
- Does it control my fan or fogger?
- No. This is a monitor — it measures and reports, and there is no relay or actuator control in the firmware. An earlier version of the project did drive a fogger and fan through relays and a hardware safety supervisor; that design was retired in favour of something far simpler to build and safer to leave running.
- Do I need to buy anything from Mushroom Minder?
- No. Chamber Controller is a DIY build from off-the-shelf parts — there is nothing to purchase from us. The GitHub repo has the parts list, the wiring, and the full firmware source.
- Do I need this to use Mushroom Minder?
- No, it is entirely optional. Every core feature of Mushroom Minder — run tracking, genetics, labels, point of sale — works with no hardware at all.
- Does connecting it cost anything?
- No. Pairing a Chamber Controller and viewing its live readings in your dashboard is included free on every plan, including the free plan.
- Do I need electronics experience?
- Very little. It is four jumper wires between a sensor breakout and an ESP32, then a USB power supply. Buy a breakout with headers already soldered on and there is no soldering at all.
- What if I get something wrong?
- This is an open-hardware project shared as-is rather than a certified appliance, so treat its readings as informational. The build itself is low-risk: everything runs at 3.3V off USB, and nothing in it touches mains voltage.
Questions? Email support@mushroomminder.com.