10. Chapter 7: OTA Update Firmware¶

It is important to frequently update the firmware of our IoT:bit because the updates may add new features, supply more sensors and actuators, or fix software bugs. In this chapter, you will learn how to update the IoT:bit firmware using OTA and develop a corresponding program. OTA (Over-the-air) is a technology that allows devices to obtain firmware or operating system updates via Wi-Fi or mobile broadband. Through OTA, you do not need to connect the IoT:bit to a computer over USB to perform updates.

10.1. How to judge if the current IoT:bit supports OTA?¶

OTA functionality is only available in firmware version 4.0 or above. You can download this makecode program to your micro:bit, the version number will be displayed on start. If the version is lower than 4.0, you need to use USB TTL to update firmware (section 10.6).

If you prefer not to update the firmware yourself, you can: 1) purchase a new iot:bit, which comes with the latest firmware pre-installed. 2) contact us for assistance with updating the firmware. Please note that you’ll need to ship the device to us, and a shipping fee will apply.

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10.2. Programming (Makecode)¶

Goal:

Develop a program to obtain updates via OTA.

Step 1:Connect WiFi

Before we download the updates via OTA, we need to connect to the network. We have already know how to connect to the WiFi in the first chapter.

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Step 2: Setup a function to show the current version

Snap a on button A pressed to stage
Go to IoT:bit -> ESP and find firmware version
Draw the firmware version variable to a show string

Step 3: Setup a function to start the OTA update

Snap a on button B pressed to stage
Show a message on the OLED to indicate that the OTA update has started
Go to IoT:bit -> ESP and snap the Update Firmware to Latest Version

Step 4: Setup a OTA update progressing listener

Snap the listener OTA Progress from IoT:bit -> ESP to stage
Draw the PercentageValue from OTA Progress to the show string to display the process percentage

Step 5: Setup a OTA update finish listener

Snap the listener On OTA Update Finished from IoT:bit -> ESP to stage
Show an icon and a message on the OLED to indicate that the OTA update has finished.
Show another message to remind you to reboot

Step 6: Setup a OTA update failed listener

Snap the listener On OTA Update Failed from IoT:bit -> ESP to stage
Draw the Message from On OTA Update Failed to the show string to show the error message

Full Solution

MakeCode: https://makecode.microbit.org/_EFiAdMEmvFqD

You could also download the program from the following website:

10.3. OTA Update¶

Goal:

Update the firmware using the program above.

Step 1: Before start

Download the program into Micro:bit
Find a place with a strong and stable WiFi connection
Turn on IoT:bit and wait for the icon “tick” showing (Wifi connected)

Step 2: Check current version

Press A to display the current firmware version

Step 3: Start OTA update

Press B to start OTA update
Check if the update is ongoing (Percentage from 0 to 100)
Do not disconnect from power / Wifi during the update process unless necessary

Step 4: Update completed

The micro:bit LED shows a smiley face, which means the OTA update is complete
Reboot the IoT:bit by turning off and on the power

Step 5: Check latest current firmware version

Press A again to check the current firmware version
Finished!

10.4. Troubleshooting on OTA Update¶

If any error message appears, please follow the instructions below and DO NOT turn off the power.

NETWORK_NOT_STABLE — Press B to retry. If this error message persists, please connect a more stable WiFi and try again.
FILE_NOT_EXIST – Please contact Smarthon

When updating firmware, please note:

Do not turn off IoT:bit and micro:bit when updating
If the update is not progressing for more than 10 minutes, you can reboot IoT:bit and try again
Make sure the WiFi network signal is stable and in good condition
Once the firmware update has started, do not execute the update function again ( do not press the button B again) unless any error message is display on the OLED

10.5. Firmware Release Notes¶

Available for ESP32

Version 4.3 — 16 Aug 2025 (Latest version)

Add the Blynk support for both write and read
http fix for post “” body handling

Download: firmware_v4.3

Version 4.2 — 30 Aug 2024

Features:‍

Add the IFTTT webhooks equivalent function

Download: firmware_v4.2

Version 4.01 — 12 Jun 2023

Features:‍

Add the ledc module back

Fixes:

Fix the issue that cannot control servo

Download: firmware_v4.01

Version 4.0 — 5 Mar 2023

Features:‍

Add OTA function API to allow user download the latest/specific version of firmware

Version 3.2

Features:‍

Add HTTP function API to allow the HTTP GET request

Version 3.1 — 17 Dec 2020

Features:‍

Add NTP function API to allow user set the Time Zone

Fixes:

Fix HTTP connection (include HTTP, IFTTT, Thingspeak, WAN/Channel Control) crash issue when received ERROR Code

Version 3.0

Features:‍

Massive modified of the Serial Table return
Compatible to latest version PXT (v0.5+)

Version 2.3

General:‍

Update the http result wording
Update the Wifi connection wording

Version 2.2

Features:‍

Update the ESP Servo AT command, now allow to control the three Servo ports by one command

Version 2.1

Features:‍

Add network status flag
Add NTP function

Fixes:

Fix the Wifi AP/hotspot mode for esp32
Fix the bug when using esp32 to perform pwm and servo control

General:

Renew the wordings
Change the pubnub connection URL to smarthon domain address

Version 2.0

Features:‍

Introduce network connection status
Update to compatible with esp32

10.6. Wired Firmware Update¶

For IoT:bit firmware versions lower than 4.0, please update according to this tutorial.

Things you need

A computer with Windows OS
4 jumpers wires (female-to-female)
USB TTL (You can buy it here or other Taobao stores)

Step 1: Install CP210x driver

Download and extract “CP210x Windows Drivers” from Silicon Labs website
In the extracted folder, execute “CP210xVCPInstaller_x64.exe” to install the CP210x driver