#New Product# Seeeduino XIAO Expansion Board – explore infinite possibilities of Seeeduino XIAO

After several months design and improvement according to users’ feedbacks , we are so thrill to announce that besides the Grove Shield for Seeeduino XIAO, we now have one more member in XIAO family – Seeeduino XIAO Expansion Board! Let’s have a first glance of final design——

Main Features

Seeeduino XIAO Expansion Board enables build prototype and project in easy and quick way. With its rich peripherals, you could explore infinite possibilities of Seeeduino XIAO.

  • Quick Prototyping: Easy debug and Reset with RESET button and SWD pin led out to male header. 0.96”OLED, enables visual data display without PC serial monitor.
  • Rich peripherals: OLED display, RTC, expandable memory space, passive buzzer, user button, on board battery management chip… One board on hand to explore infinite possibilities of Seeeduino XIAO.
  • Circuit Python Supported: Well supports circuit python. Mini SD card slot enables memory space expand, making it possible to allocate more libraries needed in prototyping and project building.
  • Mini Size: Compact and elegant with only half Raspberry Pi 4 size, perfect for tiny and wearable projects.

Mini Size

Many users adore Seeeduino XIAO because of its mini size and elegant design, so we try our best to keep the size as mini as we could when persuing the powerful function and rich interfaces. As you could see, the board is of only half Raspberry Pi 4 size.

Thouth it is designed to be such a tiny board, you may find that it has almost all useful functions you may want to build a prototype with and very rich peripherals.

Hardware Overview

Rich peripherals on board including:

  • OLED display: Visual data display without connecting to PC, which enables debug in a more efficient way, and builds application such as a sensor hub, data monitor system, .etc
  • RESET button: No more jumper wire and short circuit, easy reset with just one click.
  • SWD debug: SWD pin led out as male pin header, making debugger connection and firmware download much easier.
  • High precision RTC: High precision real-time clock with battery backup, enable maintain accurate time when the main power is turned off.
  • Expandable memory: With a mini SD card slot on the back, no worry on memory limit any more when adding libraries and using circuit python.
  • User button: Besides the RESET button, also provide with another user-defined button.
  • Passive buzzer: Same passive buzzer on Wio Terminal, with which you could change the PMW frequency to award different beep sound to get a “buzzer music”.
  • Grove connectors: All pin led out, plug and play grove connectors support common data protocols (Grove IIC2, Grove UART1, A0/D0 Grove*1)
  • Lipo Battery Charging: JST2.0mm standard lipo battery connector and battery management system, supports both USB and lipo battery power supply, and easy onboard battery recharge.
  • 5V servo connector: 5V output led out to male header for 5V servo and sensor connection.

High Cost Performance

Though with all these rich peripherals, you may find Seeeduino XIAO Expansion Board also has very high cost performance as Seeeduino XIAO does.




Seeeduino XIAO has become one of the hottest products in the Seeeduino series since its release. You may adore its small size and elegant design, powerful CPU powered by SAMD21, or rich interfaces of GPIOs, but no matter what reason makes Seeeduino XIAO attract to you, now you have one more reason now – Seeeduino XIAO Expansion Board, which will definitely help you to explore infinite possibilities with Seeeduino XIAO.

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The text here and on Wiki page https://wiki.seeedstudio.com/Seeeduino-XIAO-Expansion-Board/ both incorrectly state the design has a “mini SD” card slot, but the image at “Hardware Overview” correctly labels the slot as “MicroSD Card Slot”. I’d recommend updating the wiki page, since people looking for information probably land there first. Same goes for the Shop/Bazaar page https://www.seeedstudio.com/Seeeduino-XIAO-Expansion-board-p-4746.html .
Br from Finland,

Hi thezoikkeli,

Thanks so much for raising up this issue! You are right, we made a mistake when editting the content. Now we’ve changed the “mini SD to MicroSD”. The Expansion Board has become a hot product since its release. We really appreiciate that you noticed it and let us know. Thanks!


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I am examining the circuit diagram and have the following questions. Could you answer my question?

It seems that the 3.3V output pin12 (SYS_3V3) of the regulator inside XIAO and the 3.3V output (SYS_3V3) of the regulator ETA3410 inside XEB are connected. Will it not break down even if two outputs are connected?

Hi, it’s okay to connect these two pins.

Thank you for your answer.
Please tell me why you need to connect the two outputs.

The following is just my view.
Even though it is 3.3V output, there is a voltage difference between the outputs of the two regulators. A large current may flow through the regulator depending on the voltage difference and the magnitude of the output impedance. Of course, I think the regulator is designed to limit the current, but I don’t think it is supposed to be used to connect the outputs. Isn’t there a very high possibility of failure?

Below is a link on this subject.

The regulator of my first XEB was destroyed 10 minutes after the start of use. The second one is used without the 3.3V output pin header of XIAO to avoid destruction.

Please tell me your opinion.

there will be no problem. Please rest assured

It may be okay, but the first XEB broke in less than 10 minutes. For the second one, for my peace of mind, I cut the circuit pattern and separated the two regulators. I can use it now without any problems.

I’m only using XEB for debugging, so I’m assuming XIAO’s USB_5V powers XEB. In this case, the 3.3V generated by XIAO collides with the SYS_3V3 generated by ETA4310 of XEB. For peace of mind, I cut the circuit pattern.
However, if using the battery alone without USB, the XEB ETA3410 must power the XIAO. Do not cut the circuit pattern.

Hi, does the micro SD card only works with CircuitPython? Can I access the SD card from Arduino IDE please?