How to Build Your Arduino Sensor Kit for Robot Projects
Build your sensor kit from the modules your robot needs. The HC-SR04 measures 2 to 450 cm for $4.01, and the DHT22 reads temperature and humidity for $5.96. The PIR sensor sees motion up to 7 m away for $7.62. The RP2040 Pro Micro board runs the kit for $8.37 with 16MB of flash.
Quick facts
| Fact | Value |
|---|---|
| HC-SR04 distance | 2 to 450 cm, 0.3 cm precision, $4.01 |
| DHT22 temperature | 0 to 100% RH, -40 to 80C, $5.96 |
| BMP280 pressure | 300 to 1100 hPa, plus or minus 1 hPa, $6.77 |
| PIR motion | Up to 7 m, under 120 degree cone, $7.62 |
| MQ-2 gas | 300 to 10,000 ppm, 5V heater, $5.81 |
| TCRT5000 line | 1 to 25 mm adjustable, digital output, $7.02 |
| RP2040 board | $8.37, 16MB flash, USB-C |
What goes in an Arduino sensor kit?
A kit needs a distance sensor, a temperature sensor, and a motion sensor at least.
The HC-SR04 measures 2 to 450 cm for $4.01. The DHT22 reads 0 to 100% relative humidity and -40 to 80C for $5.96.
The PIR sensor sees motion up to 7 m away for $7.62. Those 3 modules cover most robot jobs for $17.59 in total.
Which board runs the sensor kit?
The RP2040 Pro Micro runs the kit for $8.37 with 16MB of flash.
It gives a dual-core RP2040 chip with USB-C and BOOT and RESET buttons. It runs MicroPython and QMK firmware.
The BluePill Plus board costs $11.48 with an ARM Cortex-M3 chip at 72 MHz. The ESP32-S2 Mini costs $11.16 with 4MB of flash and 2MB of PSRAM.
How do you add pressure and gas sensing?
Add the BMP280 for pressure and the MQ-2 for gas.
The BMP280 reads 300 to 1100 hPa with plus or minus 1 hPa accuracy. Its 5-pack costs $6.77 for the 3.3V version.
The MQ-2 detects smoke and gas from 300 to 10,000 ppm. It costs $5.81 with a 5V heater.
How do you add line tracking?
Add the TCRT5000 sensor for line tracking and the IR sensor for obstacle stops.
The TCRT5000 tracks a line at 1 to 25 mm with a digital output. Its 4-pack costs $7.02 for a line-following robot.
The IR sensor detects 2 to 30 cm at a 35 degree angle. Its 5-pack costs $6.20, and its 10-pack costs $8.85.
How do you test the kit on the bench?
Test one sensor at a time before you wire the whole kit.
Read the DHT22 once per 2 sec, since the sensor needs time between reads. The HC-SR04 reads 2 to 450 cm with 0.3 cm precision.
Show each reading on the 0.96 inch OLED display at $5.47. It shows 128 by 64 pixels over I2C with 4 pins.
How the options compare
| Sensor module | Measures | Range | Voltage | Price |
|---|---|---|---|---|
| HC-SR04 | Distance | 2 to 450 cm | 5V | From $4.01 |
| DHT22 | Temperature and humidity | 0 to 100% RH, -40 to 80C | 3.3 to 5.5V | $5.96 |
| BMP280 | Pressure and temperature | 300 to 1100 hPa | 3.3V or 5V | $6.77, 5-pack |
| HC-SR501 PIR | Motion | Up to 7 m | 5 to 20V | $7.62, 2-pack |
| MQ-2 | Smoke and gas | 300 to 10,000 ppm | 5V heater | $5.81 |
| IR obstacle | Obstacle | 2 to 30 cm | 3.3 to 5V | $6.20, 5-pack |
| TCRT5000 | Line tracking | 1 to 25 mm | 3.3 to 5V | $7.02, 4-pack |
How do you build the Arduino sensor kit?
- Pick the modules your robot needs from the table above.
- Pick a board to run the kit, such as the RP2040 Pro Micro at $8.37.
- Wire the distance sensor first and test its readings.
- Wire the temperature and motion sensors next.
- Add the pressure, gas, and line sensors one at a time.
- Show the readings on the OLED display and test the full kit.
Parts that fit this guide
In-stock parts ship from the New York, USA warehouse in 1-2 business days. Prices below are the live store prices we verified on November 10, 2026.
HC-SR04 Ultrasonic Ranging Sensor Module for Arduino, 2-450cm, with Mounting Bracket Options ($4.01)
HC-SR04 sensor at $4.01 listed, with a module-only option at $5.25. It measures 2 to 450 cm with 0.3 cm precision on 5V.
DHT22 / AM2302 Digital Temperature & Humidity Sensor Module ($5.96)
DHT22 sensor at $5.96. It reads 0 to 100% relative humidity and -40 to 80C on 3.3V to 5.5V.
BMP280 Barometric Pressure & Temperature Sensor Module, 5-Pack / 10-Pack, 3.3V & 5V ($6.77)
BMP280 sensor at $6.77 for a 5-pack. It reads 300 to 1100 hPa with plus or minus 1 hPa accuracy on I2C or SPI.
HC-SR501 PIR Motion Sensor Module, 2-Pack ($7.62)
PIR sensor at $7.62. It is a 2-pack that sees motion up to 7 m away, with a 0.3 to 18 sec delay.
RP2040 Pro Micro Development Board, 16MB Flash, USB-C, QMK Compatible ($8.37)
RP2040 Pro Micro at $8.37. It gives a dual-core RP2040 chip with 16MB of flash, USB-C, and BOOT and RESET buttons.
Shop the full range: Robot Sensors at Quality RC Parts. See also: Related guide.
Frequently asked questions
What does a starter sensor kit cost?
The HC-SR04, DHT22, and PIR sensors cost $17.59 in total. The RP2040 Pro Micro board adds $8.37.
Which board runs the sensor kit?
The RP2040 Pro Micro at $8.37. It gives 16MB of flash with a dual-core RP2040 chip and USB-C.
Can the kit track a line too?
Yes. The TCRT5000 sensor tracks a line at 1 to 25 mm, and its 4-pack costs $7.02.
Which sensor reads air pressure?
The BMP280 at $6.77 per 5-pack. It reads 300 to 1100 hPa with plus or minus 1 hPa accuracy.
Sources
- HC-SR04 ultrasonic sensor datasheet
- Adafruit DHT temperature and humidity sensor guide
- Adafruit BMP280 sensor guide
Last updated: November 10, 2026.