Most boards in a simulator deal in clean signals: a pin goes high, an LED turns on. DFRobot’s catalog is the other kind of electronics. A heartbeat is not clean. Neither is the CO level in a garage, the pH of an aquarium, or the question “is somebody in this room right now”. Those are exactly the sensors DFRobot is known for, and they are what this partnership brings to Velxio: hardware that measures the messy physical world, with the messy physical world simulated too, as sliders and controls you can drag while your code runs.
This is the fourth post in our series on the companies supporting Velxio, after Seeed Studio, M5Stack and Pimoroni.
Start with the UNIHIKER
The UNIHIKER M10 is DFRobot’s single-board computer for education: a 2.8 inch touch screen on the front, a full Linux system inside, Python as the first language, and edge connectors a classroom can clip things onto without a breadboard. In Velxio it boots as what it is, a small Linux machine with a screen.
Open velxio.dev/example/unihiker-system-time and press Run. This is DFRobot’s own “system time” exercise from their wiki: a Python script draws the date and a clock on the built-in screen and refreshes it once a second. Nothing about it was adapted for the simulator; the point is that the lesson a teacher already uses works as published. From there the other UNIHIKER examples go where a classroom goes: a traffic light on the edge pads, a digital piano, a starry sky you can touch, and an IoT smart home that reports into the SIoT dashboard, the way the wiki teaches it.
One note on plans: the UNIHIKER runs a full Linux guest, which is heavier than the browser boards, so it needs a paid Velxio plan. Everything else in this post, the sensors and the HuskyLens on an Arduino Uno or ESP32, runs on the free plan.
A heartbeat you can argue with
The Gravity ECG example is the one to show someone first. Wire-free, it opens with an AD8232 heart-rate front end connected to an Uno, and a red LED that flashes on every R spike, a pulse you can see on the board. Then drag the BPM slider from 40 to 180 and watch the LED keep up while the serial monitor prints the computed heart rate.
That slider is the whole idea of simulated sensors. On a desk, testing your tachycardia alarm means finding a person whose heart does 180 beats per minute. In Velxio it means dragging a control, and the alarm example does exactly that: thresholds, hysteresis, the logic you would actually have to get right before this kind of circuit is useful.
The Gravity line, six sensors in
Each of these is in the component picker today, each with its own physical control:
- C4001 mmWave presence sensor. Radar, not a PIR: it sees presence, distance and direction. The examples cover a presence readout, a night-light, distance zones and approaching-or-leaving detection.
- AD8232 ECG, as above: four examples from a serial-plotter trace to the alarm.
- MQ7 carbon monoxide. From a raw reading to a calibrated ppm readout to a three-LED air quality meter and a 200 ppm alarm.
- Analog pH kit. A readout, an aquarium range guard, a trend arrow and a two-pump dosing controller, which is a genuinely tricky control problem in twenty lines.
- Soil moisture probe. Threshold watering, a calibrated percentage with a bar graph, auto-irrigation with hysteresis and an ESP32 millivolt readout.
- DF2301Q offline voice recognition. The module that listens for “hello robot” without a cloud behind it. In the voice-controlled light you type or pick the phrase and the module reacts the way the real one hears it.
HuskyLens, an AI camera that learns
The HuskyLens is DFRobot’s camera with the neural network on board: it recognises faces, objects, colours and lines, and you teach it by pressing its learn button. In Velxio it keeps that personality. You feed it scenes, it reports what it sees over I2C or UART, and DFRobot’s own Arduino library talks to it unmodified; both of DFRobot’s official examples run as published. The gallery builds on that with a face-recognition door greeter, a pan servo that follows the object and a line-following steering signal, which is most of a robot before you own a robot.
Working with DFRobot
DFRobot supported this work and provided the hardware, and their documentation culture did a lot of the rest: every Gravity module has a public wiki page with the protocol laid out, and the UNIHIKER lessons are written down step by step. When a company documents hardware that thoroughly, “make the simulation match the documentation” becomes a testable claim, and their libraries running unmodified is the test.
We want to thank the DFRobot team for treating a browser simulator as a real place for their hardware to live. For a subject like sensors this matters more than usual: a class can calibrate a pH controller with no liquids on the table, and someone deciding whether a C4001 fits their project can find out at zero cost.
The physical hardware is at dfrobot.com, and the wiki that these examples follow is at wiki.dfrobot.com.
Every DFRobot example in the gallery
Each link opens the project ready to run.
UNIHIKER M10 (paid plan)
- System clock on the screen
- Hello on the built-in screen
- Blink an LED on edge pin 2
- Traffic light on edge pads 0/1/2
- Buttons A/B + buzzer
- Digital piano
- Emoticon master
- Starry sky (touch the screen)
- AI voice-controlled light
- Ultrasonic range finder
- Servo motor control
- Temperature and humidity monitor
- IoT smart home (SIoT)
HuskyLens
- DFRobot’s official I2C example
- DFRobot’s official UTILITIES example
- Read the detected object (I2C)
- Face-recognition door greeter
- Pan servo follows the object
- Line-following steering signal
- Drive the screen: algorithms, learning, custom text
- Photos and screenshots onto the TF card
- UART mode (TX0/RX0)
Gravity sensors
- ECG: trace on the Serial Plotter
- ECG: measure the heart rate
- ECG: a LED that beats with the heart
- ECG: tachycardia / bradycardia alarm
- C4001: mmWave presence (I2C)
- C4001: presence night-light
- C4001: distance zones
- C4001: approaching or leaving
- MQ7: read CO level
- MQ7: calibrated ppm readout
- MQ7: three-LED air quality meter
- MQ7: CO alarm at 200 ppm
- pH: read pH value
- pH: aquarium range guard
- pH: smoothed reading with trend arrow
- pH: two-pump dosing controller
- Soil moisture: watering threshold
- Soil moisture: calibrated percentage + bar graph
- Soil moisture: auto-irrigation with hysteresis
- Soil moisture: ESP32 millivolt readout
The UNIHIKER’s pinout and capabilities are in the board reference: UNIHIKER M10.
