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ESPlant - Environment Sensor Plant

Welcome to the Open Hardware Project. You can see information about this and other MiniConfs at

The ESPlant kit is designed to provide an open source platform to transmit environmental data to a central source using the power of wifi.

Assembled PCB:

ESPlant main board

Prototype board in action (before significant changes):


Check out a video of pick-n-placing components of the boards you'll be getting at LCA 2016.


  • ESP8266 WiFi enabled microcontroller. You can program it via the Arduino IDE, or alternatively Espressif SDK or esp-open-rtos.
  • Secondary microcontroller (STM32F042) acts as USB/Serial interface and i2c Analog to Digital Converter
  • Battery holder for 16340 sized 3.7V lithium cell
  • Lithium battery charger interface (solar input friendly)
  • Board automatically switches power source between solar input, battery, and USB power as applicable.

Onboard Sensors (on I2C bus)

  • BME280 Temperature/Humidity/Barometric Pressure sensor
  • ADXL345 accelerometer

External Sensors (all optional, connected to screw terminals)

  • 2x soil moisture sensors (via ADC pins)
  • DS18B20 connected to GPIO 12.
  • PIR (infrared motion) sensor connected to GPIO 15.
  • WS2812B LED strip connected to GPIO 13 (mislabelled as 15 on V1.3 PCB!)

The 3.3V "VSens" power rail is switchable on/off by the microcontroller. It defaults to unpowered (off). The GPIO to use is 14, and it is active low (ie driving the output low turns VSens on, driving it high turns it off).

Assembly Steps

Assembly guide on the wiki.

Using with Arduino

To add ESP8266 support to the Arduino IDE (1.6.6 or newer) we use the external ESP8266 Arduino project. We need the staging version not the stable version of the ESP8266 support package.

Follow these steps to install:

  • Install Arduino 1.6.6 or newer (1.6.7 is fine) from the Arduino website.
  • Start Arduino IDE and open Preferences window.
  • Enter into Additional Board Manager URLs field. You can add multiple URLs, separating them with commas.
  • From the Tools menu choose Board -> Board Manager
  • A window will open. Search for ESP8266.
  • Choose a version from the drop-down in the bottom right. There will probably only be one shown there.
  • Click Install

Connecting ESPLant to your computer

  • No drivers required on Linux, OS X, or Windows 10.
  • No manual reset or button pressing dance required to program.
  • In ESP8266 Arduino IDE, under Tools menu, set Board to "NodeMCU V1.0" (fully compatible).
  • Can set upload speed to 230400. 460800 works in most cases (you might get occasional failures at 460800)

Getting ESPlant

You need to clone the ESPlant repo from github, using the --recursive option to pick up submodules. If you download a zip file then the submodule parts will be missing, so we recommend using git to get it.

The command is:

git clone --recursive

Libraries you will need

Arduino uses libraries to work with additional hardware or software functionality in an easy way. Normally you can download and install libraries directly inside the Arduino IDE by choosing Sketch menu -> Include Library -> Manage Libraries.

One library that you should install this way is the OneWire library. Search for "OneWire" and then click the Install button to install it.

For the ESPlant the other required libraries are set up as "git submodules" inside the "Libraries" directory. If you did a "recursive" clone then you will have these, otherwise you can add them to a "normal" clone by running this command:

git submodule update --init

Inside the Libraries directory there is a script that you can run on Linux or OS X to symlink all of the libraries into your Arduino libraries directory so you can use them.

cd Libraries

On Windows you'll need to copy all the subdirectories of the libraries directory (copy them into the My Documents/Arduino/libraries directory).

The one Library here that is part of this repo (not a submodule) is the "ESP_Kwai" library that acts as a bridge to the peripheral hardware.

Don't forget OneWire as well (see above).

Upload your first program ("sketch")

After restarting Arduino IDE to pick up the new libraries, you're ready to upload your first program (Arduino calls them "sketches"):

  • Choose File->Open in Arduino and open the Firmware/ESPlant_serial_sensor from this repository. This is a simple sketch that outputs all the analog values read by the board.
  • Press the "Upload" button to send it to your board. Watch for messages indicating the upload was successful.
  • Open the serial monitor (under Tools) and set the baud rate to 115200 in order to watch the output from the sketch.

Other Sketches to Try

The repo includes the following sketches:

  • ESPlant_prodtest is the hardware production test. It tests all the sensors to confirm the hardware is good. There are instructions in a large comment at the top of the sketch. You can run this if you think you're having hardware problems, or to look at example code for any individual point.

  • ESPlant_MQTT_sensor uses MQTT to push data to a server. It includes easy provisioning mechanisms for connecting to the WiFi. It has other instructions in its README file for WiFi configuration.

Where to Now?

Check out (and contribute to) the wiki. There is a pinout summary, sensor summary, power information, etc.

Onboard STM32

There is an onboard STM32 microcontroller that acts as USB/Serial converter and an i2c connected ADC (Analog/Digital Converter) device.

For the i2c functionality, the ESP_Kwai library (under Libraries/ESP_Kwai) acts as a bridge (get it) to the i2c ADC peripherals on the ESPlant. It can automatically read all the values connected to the ADC and return them.

If you want more information on how the STM32 works internally, check out the README in the STM_Firmware directory.


This project was designed by the 2016 Open Hardware Team!

Made at!


To the HackMelbourne (CCHS, community of Melbourne, Australia.

To all other open-source developers whose countless hours supported every other aspect of this design.


The specific terms of distribution of this project are governed by the license referenced below. Please contact the copyright owner if you wish to modify the board for distribution. Please utilize this design for personal or research projects. Please acknowledge all contributors.


Licensed under the TAPR Open Hardware License ( The "license" sub-folder also contains a copy of this license in plain text format.

Copyright John Spencer, Angus Gratton, Andy Gelme, Jon Oxer 2015


Environmental Sensor Plant - solar WiFi gardening/meteorological sensor using ESP8266







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