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Elecfreaks IoT:bit for micro:bit


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IoT:bit is an expansion board for exploring IoT with micro:bit.

It uses an ESP8266 chip for WiFi and serial port to communicate with the micro:bit. It also has breakouts for most I/O ports of the micro:bit to hook up  3V devices such as LEDs, photosensors or servos.

IoT:bit additionally has an on-board buzzer and RTC clock for maintaining accurate time without a power supply. 


- Integrated ESP12F WiFi, RTC and passive buzzer module
- Extends most I/O ports 
- Silk-screen labels for main 
onboard components
- Separate I2C interface, to directly plug in OLED, BME280, etc
- Lego spaced mounting holes (4 standard spacing Lego fixed holes)

- Product size:71mm x 63mm x 23mm
- PCB thickness:1.5mm
- Hole diameter:2.4mm


Pin interface drawing


Introduction of main module


Software support


Makecode block


Click on `JavaScript` of the `makecode` for `JavaScript` coding.



Using `MU` for advanced coding method`MicroPython`


Easy start 

Hardware connection

First, install CR1220 button cell for power supply to the Real Time Clock (optional, use only if you need RTC functionality)


Plug in the micro:bit.

Use a single USB for power supply and power on. 


Coding Platform


Add codebase

Click on "Advanced" in the MakeCode Drawer to see more code sections.


We need to add an extension for coding to the IOT. Click on the “Extension” at bottom of coding drawer, then Search for “IOT” and click on the IOT package to add it to your project. (As below picture) 

Note:If you get a warning telling you some packages will be removed because of incompatibility issues, either follow the prompts or create a new project in the Project file menu.

How to drive the buzzer

There is on-board buzzer on the IoT:bit. The buzzer can be connected to the PO of the micro:bit to play music by the 'music' functions in makecode.


When Button A is pressed, play a bit of music.

Program link:

How to use the RTC

There is an on-board DS1307RTC timer on the IoT:bit. The RTC timer needs a CR1220 button cell for lasting power supply. 


Here are instructions to press button A to set the time to the set time.

  • Drag out an 'On Start' block & add the RTC function block.
  • Enter the appropriate values to be displayed on the 5*5 LED array.
  • Upload this to the micro:bit
  • Then turn off the power for one minute, then on again and the dot matrix display will show the time.

Program link:

How to use the internet function

The most important function of IOT:bit is WiFi. The onboard ESP WiFi module can connect to WiFi and send information. To use this port for communication with the micro:bit use the pin `RX-P8`,`TX-P12` is special for IoT.

On start, initialize ESP8266 to default connection with P8 & P12.
Connect your own WiFi, input the key and the password.
Under forever loop, connect the 'thingspeak' chip and set date to send, then pause. 

Program link:

Download code

Let your micro:bit be connected to one side of the USB, the other side to your computer. Inserting on the expansion board may cause the micro:bit connection to be abnormal.

Then copy your documents to the micro:bit. 

Use the on-board micro USB for power, not transferring files.