Seeed Studio makes some of the smallest development boards you can buy. A XIAO is about the size of a postage stamp, and around it Seeed has built a whole family: a round touch screen that plugs straight onto the board, Grove sensors that need no soldering, and a voice capture board with a real XMOS DSP on it. Starting today, that family is in Velxio, and it runs on the free plan.
This is the first post in a short series about the hardware companies that support Velxio. We are starting with Seeed Studio because their boards were the ones people asked for the most, and because the modules around the XIAO make good demos of what a browser simulator can do when it has the real hardware to compare against.
Start with the clock
The best introduction is the Round Display itself. The shield carries a 1.28 inch round screen, a touch controller, a real-time clock chip, a microSD slot and a battery connector, and a XIAO plugs onto the back of it. In Velxio it opens the same way it ships: the XIAO already seated on the socket, nothing to wire.
- Open velxio.dev/example/seeed-round-display-clock. You do not need an account.
- On the toolbar at the top, click the play button to run the project. The sketch compiles on Velxio’s servers (a cold build can take a few minutes; later ones are much quicker) and then the XIAO boots.
- Watch the round screen. The sketch draws an analogue face and reads the time from the PCF8563 clock chip on the shield, so the hands move because the clock ticks, not because the sketch counts milliseconds. The serial monitor at the bottom prints the same time once a second.
- Now edit the sketch. Change the colour of the seconds hand, or set a
different time in
setup(), and run it again.
The pins in that sketch are Seeed’s own (CS=D1, DC=D3, BL=D6, and
the SPI bus on D8/D10), written as raw GPIO numbers so the code says
what it means. If you drive the backlight pin low, the glass goes dark,
exactly as it does on the bench. Sketches written for the real shield run
here unchanged, and sketches you write here run on the real shield.
What is in the catalog
The XIAO boards
Five XIAO boards are in the picker. Two of them, the XIAO ESP32-S3 and the XIAO ESP32-C3, are also part of the open-source Velxio release. The other three are hosted on velxio.dev:
- XIAO ESP32S3 Sense. The ESP32-S3 with the camera module, a PDM
microphone and a microSD slot on the expansion board. In Velxio the
camera is your webcam:
esp_camera_fb_get()returns real frames, and the gallery example saves JPEG photos to the emulated card. The microphone is your computer’s microphone, switched on with the Mic toggle in the canvas header. - XIAO ESP32C6. The RISC-V ESP32-C6, with the same Arduino, MicroPython and ESP-IDF choice as the rest of the ESP32 family in Velxio.
- XIAO RP2040. The RP2040 in the XIAO footprint, with its user RGB LED wired active-low the way the board has it. This one runs on the same in-browser RP2040 engine as the Raspberry Pi Pico.
The Round Display for XIAO
The shield from the clock example. Every part of it does something:
- The 240x240 GC9A01 screen paints whatever your sketch sends over SPI, with the same command set the real panel speaks.
- Touch works: click on the glass and the CHSC6X controller reports the point over I2C.
- The PCF8563 real-time clock keeps time and answers on I2C, so RTC-based sketches behave like they do on hardware.
- The TF slot is a real FAT card. Your project’s data files are copied onto it, and you can upload your own images or data through the component’s SD Card panel.
- The battery gauge is a slider: move the simulated battery voltage and
watch the reading on
A0change.
Grove Smart IR Gesture Sensor
The gesture sensor is the module people find most surprising. Seat a XIAO ESP32C6 on its socket and there is nothing to wire; the socket carries the I2C bus. When the simulation starts, the sensor asks for your webcam, and the gestures it recognises come from your actual hand: swipe left and right, push, rotate, finger counting, pinch, grab, thumb up and thumb down. The result your sketch reads over I2C is the same register block the PAG7660 chip produces, and the recognised gesture flashes on the board’s silkscreen so you can see what it saw. The four-way DIP switch selects I2C or SPI, as on the hardware, and there is an example for each.
ReSpeaker Lite
Seeed’s far-field voice board, built around an XMOS XU316. It sends 16 kHz audio to the host XIAO over I2S and takes control commands over I2C. In Velxio it listens through your microphone, plays sketch output through your speakers, and its MUTE and USR buttons and red LED are live. Four examples cover the mic level meter, playing a melody, tracking the direction a voice comes from, and the buttons and control bus.
Working with Seeed Studio
Emulating a module properly needs the module on the desk. Seeed Studio supported this work and provided the hardware, so every board and shield above was modelled next to the real thing: the Round Display pinout was taken from Seeed’s own board configuration and schematics, the gesture sensor’s registers were checked against Seeed’s driver, and the sketches in the gallery are the ones you would write from the Seeed Studio wiki.
We want to thank the Seeed Studio team for that support, and for treating a browser-based simulator as a serious place for their hardware to live. The result is good for everyone who teaches or learns with a XIAO: you can try the Round Display before you order it, prepare a classroom exercise without a box of shields, or check that a sketch behaves before you flash the board in front of you.
If you want the physical parts, they are on seeedstudio.com: the XIAO ESP32S3 Sense, the XIAO ESP32C6, the XIAO RP2040, the Round Display for XIAO, the Grove Smart IR Gesture Sensor and the ReSpeaker Lite.
All of the Seeed Studio hardware in Velxio is available on the free plan. The boards appear in the component picker under Boards, the modules under their categories, and each one has a datasheet card with the pinout and a link to Seeed’s product page.
Every Seeed Studio example in the gallery
Each link opens the project ready to run. The board named in brackets is the one the example ships with.
XIAO boards
- XIAO ESP32S3 Sense: Hello (XIAO ESP32S3 Sense)
- XIAO ESP32S3 Sense: onboard microSD (XIAO ESP32S3 Sense)
- XIAO ESP32S3 Sense: PDM microphone level (XIAO ESP32S3 Sense)
- XIAO ESP32S3 Sense: camera photos to microSD (XIAO ESP32S3 Sense)
- XIAO ESP32C6: Blink (XIAO ESP32C6)
- XIAO RP2040: Blink (XIAO RP2040)
- XIAO RP2040: on-board RGB LED (XIAO RP2040)
- XIAO RP2040: button cycles the on-board RGB (XIAO RP2040)
- XIAO RP2040: traffic light (XIAO RP2040)
Round Display for XIAO
- Round Display: analogue clock (GC9A01 + RTC) (XIAO ESP32S3 Sense)
- Round Display: files on the microSD (TF slot) (XIAO ESP32S3 Sense)
- Round Display: battery gauge (ETA3410 divider) (XIAO ESP32S3 Sense)
- Round Display: read the PCF8563 clock (I2C) (ESP32 DevKit)
Grove Smart IR Gesture Sensor
- Grove Smart IR Gesture: a XIAO on the socket, no wires (XIAO ESP32C6)
- Grove Smart IR Gesture over SPI (flip the DIP) (XIAO ESP32C6)
- Grove Smart IR Gesture: read the actual IR image (XIAO ESP32C6)
- Grove Smart IR Gesture: thumb mode (and the tuning registers) (XIAO ESP32C6)
- Grove PAG7660: read a gesture (I2C) (ESP32 DevKit)
ReSpeaker Lite
- ReSpeaker Lite: far-field mic level meter (I2S) (XIAO ESP32C6)
- ReSpeaker Lite: play a melody through your speakers (XIAO ESP32C6)
- ReSpeaker Lite: track the talker (DOA + VNR over I2C) (XIAO ESP32C6)
- ReSpeaker Lite: buttons and the XU316 control bus (XIAO ESP32C6)
The board pages in the documentation have the full pinouts: XIAO ESP32S3 Sense, XIAO ESP32C6 and XIAO RP2040. The next post in this series is about M5Stack.
