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Build a low-voltage thermostat prototype that reads a thermistor, displays an estimated temperature, sounds a buzzer above 30°C (86°F), moves a servo, and can publish readings over MQTT. It is a learning project—not a safe or complete controller for household heating or cooling equipment.
Make: describes the build as an easy, roughly one-hour project; actual time depends on your familiarity with breadboards and NanoPy. The project appeared in November 2024 and the page was updated in February 2025, so check current kit contents and software controls before following edition-specific details.
What the project does
The word “thermostat” here describes a temperature-responsive demonstration, not a residential HVAC system. A 10 kΩ NTC thermistor and 2.2 kΩ resistor form a voltage divider. The Oxocard reads the divider through an analog input and converts that reading into an estimated temperature. The screen shows the result; a piezo sounds above 30°C; a servo provides a visible mechanical response; and an optional MQTT connection sends readings to a broker.
The project does not switch a furnace, boiler, air conditioner, mains heater, or relay. The servo is an indicator or simulated actuator, not a heating-system control. Do not connect this prototype to mains equipment or rely on it for unattended temperature control.
#1 Best Overall
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- 235 PARTS FOR REPEATABLE EXPERIMENTS - Includes a 400-tie-point solderless breadboard, power module, jumper wires, Dupont wires, potentiometer, buttons, LEDs, resistors, capacitors, diodes, transistors, buzzers and light-sensitive components
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- COMPONENT KIT WITH CLEAR EXPECTATIONS - A controller board, programming cable and wall power adapter are not included; use a compatible microcontroller for coded projects and follow the current tutorial, datasheets and wiring guidance
What you need
- Oxocard Connect and its breadboard cartridge.
- 10 kΩ NTC thermistor and 2.2 kΩ resistor.
- SG92R microservo, piezo buzzer, and jumper wires.
- USB power source (not included with the Connect, according to Oxocard).
- A computer or tablet with a modern browser to use the NanoPy editor.
- For MQTT: Wi-Fi access and a reachable MQTT broker, plus credentials if required.
The standard Oxocard Innovators Kit listing describes the Connect, breadboard cartridge, and 96 components. Make: describes its Make: Edition as having around 30 electronic components. These descriptions refer to different editions; do not assume the component count or every hardware detail is identical. The official Connect page describes an ESP32-based device with a 240×240 RGB display, Wi-Fi, USB-C, joystick, and 16-pin cartridge connector. Make: specifies an ESP32-S3 for its edition. Confirm the exact board and included parts you have.
The basic breadboard build requires no soldering, as described by Make:. The wider component assortments include parts for other experiments, such as LEDs, buttons, a photoresistor, potentiometer, and PIR sensor.
How the sensor circuit works
An NTC thermistor’s resistance falls as it gets warmer. In a voltage divider, it shares the supply voltage with the fixed 2.2 kΩ resistor. The voltage at their junction changes as the thermistor resistance changes; the Connect’s analog-to-digital converter (ADC) measures that voltage. Software then uses the thermistor’s characteristics to estimate temperature.
3.3 V ── 2.2 kΩ resistor ──┬── thermistor ── GND
│
IN06This diagram shows the divider arrangement used here, with the junction going to IN06. The precise physical breadboard holes do not matter, but each component lead must occupy the intended electrical row. Do not put both leads of a component into the same connected row. Verify the cartridge’s supply and pin labels for your edition before powering it.
Rank #2
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- START WITHOUT SOLDERING — Plug-in modules, a solderless breadboard and the pre-soldered LCD help beginners focus on wiring, code and testing; the illustrated component list makes it easier to find each part and move from one lesson to the next
- LEARN THE LOGIC, THEN CREATE YOUR OWN — Use Arduino IDE and the included example code to understand digital input and output, analog sensing, timing, motor control and display functions, then change thresholds, speeds and sequences for alarms, environmental monitors, reaction games and motion projects
- CLEAR SETUP SUPPORT FOR FIRST-TIME BUILDERS — Download the latest tutorial and code, select the UNO board and correct computer port, check component polarity and breadboard rows, and keep power-module input at 9V or below; younger learners should work with an experienced adult
A wrong divider arrangement, missing ground, floating ADC input, or incorrect thermistor conversion can produce implausible readings. The voltage-divider measurement is not inherently a calibrated thermometer: use the correct conversion parameters for the thermistor and validate readings against a known thermometer at several room conditions. Avoid holding the thermistor while checking a stable room reading, since fingers warm it.
Read and display the temperature
Open the browser-based NanoPy editor. NanoPy is a Python-inspired language based on MicroPython; Oxocard also provides NanoPy source and examples. Make: gives this core program flow:
while true:
clear()
adcValue = readADC(IN06, 100)
T = calculateTfromA(adcValue)
drawText(10, 90, "T = " + T + "°C")
update()
delay(1000)Treat this as the project’s example flow, not guaranteed universal syntax for every editor or firmware version. Check the current NanoPy examples and command reference for exact function names and conversion helper availability. In the example, readADC(IN06, 100) samples the analog input using the provided averaging parameter; calculateTfromA stands for the thermistor conversion; the display is updated in Celsius; and the one-second delay sets the approximate refresh interval. Do not substitute an arbitrary thermistor equation: its constants depend on the actual sensor.
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Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallFor a first test, get the sensor and display working before attaching the servo or MQTT. A stable reading near room temperature is a better milestone than simply seeing a number. If the display is blank, run a minimal display-only example, confirm the Oxocard is powered and recognized by the browser, and check that the program reaches its display update rather than failing in sensor conversion.
Rank #3
- Highest Cost Components Kit: It comes with more than 300pcs sensors and components for fun and simple electronic projects.
- Safe and Secure Pakcage: Resistors/LED/Transistors and Integrated Circuits are individually packaged and labeled, and well-stored in a sturdy box
- The Breadboard Power Supply come with a USB Power Cables,which is hard to find.
- Datasheet is available to download from our official website or you can contact our customer service.
- Not including the controller board.
Add the piezo alarm
The Make: example connects the piezo to IO02, uses 50 Hz PWM, and activates it when temperature is greater than 30°C (86°F). Its representative condition is:
if T > 30:
writePWM(IO02, 4096/2)
else:
writePWM(IO02, 0)Use the PWM setup and output behavior appropriate to the current NanoPy version and your cartridge. A passive piezo may need an oscillating tone signal; if it stays silent, test it with a standalone tone example and confirm the pin assignment and wiring. You can temporarily lower the threshold to verify the alarm, then restore 30°C.
The simple threshold has no hysteresis: a noisy reading hovering around 30°C can repeatedly turn the alarm on and off. A steadier design turns it on at 30°C and does not turn it off until the temperature falls to 29°C. Adapt this logic to verified NanoPy syntax:
if not alarm_on and T >= 30:
alarm_on = true
if alarm_on and T <= 29:
alarm_on = falseShowing an on-screen alarm state also helps distinguish a threshold that has not been reached from a wiring or sound-output problem.
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Add the servo as a visual indicator
The servo can move a pointer or flag to make the temperature response visible. Make: says the project configures 50 Hz PWM for the servo. Use a bounded temperature range and map it to a conservative, useful servo range; clamp the result so a calculation cannot command an out-of-range position. Test a fixed neutral position first. Do not force the horn against a mechanical stop or attach a mechanism that can injure someone or damage property.
Servo movement can draw more current than the controller output can comfortably supply, causing jitter, resets, or unreliable sensor readings. Follow Oxocard’s power guidance for your exact hardware. If a separate supply is permitted and needed, use the correct voltage and connect grounds appropriately; do not improvise power connections. A servo is only a demonstration actuator in this project, not a safe HVAC interface.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Optional: publish readings with MQTT
MQTT sends a message to a broker; it does not automatically provide a dashboard or remote thermostat control. The broker must already be running and reachable from the Oxocard. Make: shows this basic pattern:
uri = "mqtt://ip-address"
connectMQTT(uri, username, password)
publishMQTT("Temperature", T)Replace the placeholder with the broker’s reachable address and use valid credentials where required. Start with a broker on the same local network, confirm the port and authentication settings, and publish a numeric Celsius value to a clear topic such as home/lab/oxocard/temperature. Confirm reception with another MQTT client.
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Plain mqtt:// is not encrypted TLS MQTT. Do not expose an unauthenticated broker to the public internet or send sensitive data over an untrusted network. The short example does not establish robust reconnect behavior: add connection-state feedback and retry/backoff so a Wi-Fi or broker interruption does not silently end publishing. Keep the sensor display usable when MQTT is unavailable.
Save and run the program
Make: says the script can be saved to the breadboard cartridge’s EEPROM and configured to autostart when the cartridge is inserted. The exact current editor labels and transfer controls may change, so follow the prompts shown by your installed NanoPy workflow rather than relying on a fixed menu path. First run the program manually, then save it to the cartridge and enable autostart if offered. If startup fails, disconnect or remove the cartridge as appropriate for the device, return to manual execution, and test a minimal script. Network-dependent code should time out or continue in offline mode rather than blocking the display at boot.
Checkpoints and troubleshooting
- Temperature is far too high or low: Check the 3.3 V and ground ends, confirm the junction reaches
IN06, verify the resistor value, and recheck the thermistor conversion and units. A floating ADC input can give erratic results. - Reading jumps around: Confirm secure breadboard contacts and consider averaging more samples or smoothing readings. Keep the thermistor away from warm fingers and nearby heat sources.
- Screen stays blank: Confirm USB power and device recognition, then run a display-only example. A crash before the first update can look like a display fault.
- Piezo is silent: Check the output assignment and wiring, test a standalone tone, and temporarily lower the threshold. Verify whether your piezo requires a tone rather than a simple static output.
- Servo jitters or does not move: Test neutral position, confirm 50 Hz PWM and wiring, reduce the movement range, and investigate power capacity before assuming the code is at fault.
- MQTT will not connect: Verify the broker address from the same network, Wi-Fi, credentials, port, and protocol requirements. Display connection status and retry after failures.
A useful definition of success is: a stable, plausible room-temperature reading; an alarm that activates at the chosen threshold without chattering; predictable bounded servo motion; and a numeric MQTT message visible at the broker when networking is enabled.
What to try next—and who this kit suits
Once the basic loop works, add a user-adjustable setpoint with the joystick or potentiometer, record minimum and maximum temperatures, show the alarm and network state, or publish a last-update time. A digital temperature sensor may improve repeatability, but it requires a different wiring and software path. Advanced actuator experiments need a separately designed, correctly isolated low-voltage interface and should not be treated as a route to controlling mains equipment.
The Connect is a good fit if you want an integrated display, cartridge-style breadboarding, guided editor, and immediate feedback while learning sensors, ADC, PWM, and MQTT. Its convenience and educational ecosystem are less relevant if you only need an inexpensive temperature monitor or want a standard Arduino-compatible board with a broader generic ecosystem. The official Oxocard open-source page links hardware designs, parts information, firmware, and NanoPy resources for readers who want to explore further. Kit editions differ, so check the included parts for the edition you are considering.
Quick Recap
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