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Environmental Sensing


Environmental Monitoring for the Internet of Things

$3,034 raised

of $3,000 goal

101% Funded! Order Below

Funding ended on Sep 03, 2020 at 04:59 PM PDT.

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Affordable, Open Source, IoT Dev Board

We designed EMIT for projects related to environmental monitoring and control—for use as a smart greenhouse controller, a central heating thermostat, or an environmental data logger, among other applications—but it’s well suited to a wide range of tasks thanks to its feature set, its expandability, and its wall-mountable industrial design. In particular, EMIT is an ideal platform for teaching or learning about the hardware, software, and design aspects of IoT product development.

Plug Your ESP32 Into the World Around It

EMIT was built around the popular 30-pin DOIT ESP32 DEVKIT V1, which is a low-cost, low-power, dual-core, wireless IoT board with integrated Wi-Fi and Bluetooth connectivity. The ESP32 module itself is extremely well supported, of course, and you will find a number of websites and blogs that offer tutorials on both Python and Arduino development.

The 30-pin version of the DEVKIT V1 is affordable and easy to find, both on Amazon and elsewhere. Its schematic has been published online and there are a number of websites with additional information about the board.

All the bits. (Click to expand)

In addition to the ESP32, a microSD card socket, and a DC input connector, EMIT includes several key components related to environmental monitoring and control: an AM2302 temperature and humidity sensor, a 5 A relay with a status LED, two user-programmable LEDs, and a 12-pin expansion connector with which you might add a soil moisture probe, an ambient light sensor, an additional relay, a camera, or some other peripheral that is not integrated into the board itself.

Looking the Part

Like many products, EMIT started life as a simple breadboard project—a quick way to log the temperature and humidity of our basement so we could determine just how bad that winter really was. But I soon realized two things: first, that we could use it for many other purposes, especially if I added a relay; and second, that I would need to make it a whole lot better looking if I wanted my wife to let me hang it on a wall.

EMIT mounted on the wall

After three more iterations, EMIT is not only stable, reliable, and easy to use, it also fits inside a low-cost, vented, wall-mounted enclosure that will look good just about anywhere.

Program in Python or Arduino

EMIT can be programmed using either MicroPython or Arduino (C/C++). We will provide step-by-step firmware-development tutorials in both languages so that you can develop EMIT applications in your preferred language.

Support for Every Stage of Your Project

We’re not interested in just selling a few boards. We created EMIT specifically to help people discover, utilize, and enjoy IoT technology. We designed it to make the hardware element easy, but we have not forgotten about the rest: the firmware, the MQTT broker, and the applications. Accordingly, we intend to publish a full range of tutorials, make our free MQTT broker available for use, and provide working sample code both for EMIT and for various client applications. Finally, we will launch a dedicated forum for EMIT users and do everything we can to help build a rich, self-supporting community around it.


Technical Specifications

Temperature Measurement
Range-40° to +80° C
Resolution0.1° C
Accuracy (Typical)+/- 0.5° C (+10° C to +55° C)
+/- 1.5° C (< 10° C or > 55° C)
Max Error+/- 2.0° C (at < 10° C or > 55° C)
Repeatability (Typical)+/- 0.2° C
Read Frequency2 seconds max
Humidity Measurement
Range0 to 99.9 %RH
Resolution0.1 %RH
Accuracy (Typical)+/- 2 %RH (20% to 80%)
+/- 3 %RH (< 20% or > 80%)
Max Error+/- 5 %RH (at < 20% or > 80%)
Repeatability (Typical)+/- 1 %RH
Read Frequency2 seconds max
Power Requirements
Voltage Range7 to 12 VDC
Power Consumption50 mA typical
Physical Dimensions
Width81 mm
Height81 mm
Depth18 mm


EMITArduino MKR Wi-Fi 1010 + AM2302MXCHIP AZ3166 IoT DevKit
Components EMIT Board + ESP32 Module An Arduino MKR Wi-Fi 1010, an AM2302 sensor, a relay Module, and a microSD PCB An MXCHIP AZ3166 IoT DevKit, a relay Module, and a microSD PCB
Published schematicsYes Yes Yes
All-in-one solutionYes No No
Enclosure availableYes No No
Operating voltage7 - 12 VDC 7 - 12 VDC 5 V (USB only)
Temperature Sensor40° to +80° C (integrated) 40° to +80° C (separate PCB) 40° to +80° C (separate PCB)
Humidity Sensor0 to 99.9 %RH (integrated) 0 to 99.9 %RH (separate PCB) 20 to 80 %RH (separate PCB)
Relay5 A SPST (integrated) 10 A SPDT (separate PCB) 10 A SPDT (separate PCB)
SD Card holderIntegrated Separate PCB Separate PCB
LEDs2 1 2
ADC pins4 6 2
ADC resolution16 bits 12 bits 12 bits
Arduino supportYes Yes Yes
MicroPython supportYes No No
Dimensions (LxWxH)81 x 81 x 18 mm 69 x 54 x 15 mm 140 x 100 x 21 mm
Price (US shipping)$29 $65.51 $70.90

Support & Documentation

Our goal is to make EMIT the perfect starting place for your next IoT project, regardless of your ambitions or skill level. To that end, we will provide step-by-step firmware development guides for both MicroPython and Arduino, a free MQTT broker, a sample Python MQTT application client, and an online support forum. You can reach us through the Ask a technical question form on our campaign page.

The EMIT GitHub repository will contain all examples, guides, and hardware files as we add to it. Board schematics are already published

Manufacturing Plan

All PCB fabrication and assembly will be carried out by a professional contract manufacturer (CM) chosen from a short list of four providers based on cost, reliability, and capability. We have partnered with this CM before, including on the production of prototype EMIT boards. Once assembled, all boards will come to ControlBits for inspection, testing, final assembly into kits, and packaging.

Fulfillment & Logistics

All boards and kits will be shipped to backers by Crowd Supply’s parent company and fulfillment partner, Mouser Electronics, approximately two months after the end of the campaign. The cost of delivery to US customers is included in the prices shown on the campaign page. International shipments are subject to an additional surcharge, which is displayed just below the product description.

Please see Crowd Supply’s article on Ordering, Paying, Shipping: All the Details for more information on delivery, VAT payments, etc.

Risks & Challenges

As mentioned above, EMIT is now in its third revision, so the hardware and the sample code are both quite stable. There is always some risk, with a project of this nature, that limited availability of key components will delay manufacturing, but we have tried to minimize that risk by pre-ordering unique parts with long lead times. As a result, we are reasonably confident that we will hit the schedule we have set for ourselves. Regardless, we will keep you informed with regular updates as the campaign unfolds.

In the Press

Produced by ControlBits in Wales, United Kingdom.

Sold and shipped by Crowd Supply.

EMIT - Board Only

A dev board with a socket for a 30-pin DOIT ESP32 DEVKIT V1 (not included), an integrated temperature and humidity sensor, a microSD slot, an I/O expansion socket, and an 5 A SPST relay.

$29 $8 US Shipping / $18 Worldwide

Want to buy this item? Check the current project page for the latest information.

EMIT - Full Kit

A Wi-Fi- and Bluetooth-enabled ESP32-based dev board with an integrated temperature and humidity sensor, a microSD slot, an I/O expansion socket, and an 5 A SPST relay. Includes a 30-pin DOIT ESP32 DEVKIT V1, a custom enclosure, an 8 GB microSD card, and a USB cable.

$59 $8 US Shipping / $18 Worldwide

Want to buy this item? Check the current project page for the latest information.

About the Team


Wales, United Kingdom  ·

At Control Bits we're dedicated to building great IoT products that are open to everyone through education, hardware development kits, and open source software. Along the way we aim to build an open and vibrant community.

See Also

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