9521 – Flame Sensor/en

Documentation notice: This technical documentation was independently rewritten from an archived supplier source. Check technical details and commands against the product version and manufacturer documentation before use.

Summary

Technical overview of the Waveshare Flame Sensor: features, pinout, and integration with Pico, STM32, and Arduino UNO.

Related products at JW Tech

• 9521 – Flame Sensor
• WSAL9521 – Flame Sensor

Technical overview

• The sensor responds to a flame spectrum from 760 nm to 1100 nm with a detection angle of 0–60 degrees.
• It uses an LM393 comparator with adjustable sensitivity via an onboard potentiometer.
• Power supply is 3.3 V to 5.3 V; operating temperature range is -25 °C to 85 °C.
• Module dimensions are 27.3 mm × 15.4 mm; mounting holes are 2.0 mm in diameter.
• Pinout: DOUT (digital output), AOUT (analog output), GND, and VCC power input.
• For Raspberry Pi Pico wiring: VCC to 3.3 V, GND to GND, AOUT to GP26, DOUT to GP22.
• Pico examples include C/C++ and MicroPython; firmware must be flashed to the Pico before use.
• For STM32F103RBT6: VCC to 3.3 V, AOUT to PA6, DOUT to PA4; examples use the HAL library and Keil MDK-ARM project.
• For Arduino UNO: VCC to 5 V, AOUT to A0, DOUT to D2; load and upload Flame_Sensor.ino via Arduino IDE.
• With a flame height of 5 cm, the detection distance is approximately 1 m per the FAQ.
• Sensitivity can be adjusted by turning the potentiometer on the module.

Commands and examples – verify before use: 

sudo apt-get install p7zip-full
cd ~
sudo wget https://files.waveshare.com/upload/d/d8/Flame-Sensor-code.7z
7z x Flame-Sensor-code.7z -o./Flame-Sensor-code
cd ~/Flame-Sensor-code/Pico/c/build/
export PICO_SDK_PATH=../../pico-sdk
cmake ..
make -j9
cp main.uf2 /media/pi/RPI-RP2/

Notes and version constraints

• Example files target specific board variants (STM32F103RB, Arduino UNO); other boards require adapted wiring and code porting.
• The Pico firmware version is version-sensitive; the source recommends using the firmware from the demo codes archive.
• The stated detection distance (1 m at 5 cm flame) comes from the FAQ and should be human-confirmed before use in safety-critical applications.
• No safety, certification, or warranty claims are present in the source; these must not be added.

Source and revision record

• Flame Sensor - Waveshare Wiki
• Source revision: 68921
• Captured: 2026-08-29T09:31:44+00:00
• SHA-256: 2ae99689d81b9b08511cfcbad42e51731b526d4b8d3db8b70ec792b100d90dd6