HS-S07A Flame Sensor Module - Dual Analog/Digital Output, 3.3V-5.5V

The HS-S07A module is designed to operate from a 3.3V to 5.5V DC power supply. This wide range makes it directly compatible with both 5V systems like most Arduino boards and 3.3V logic systems such as Raspberry Pi, ESP32, or STM32 microcontrollers without requiring a level shifter.

Connect the VCC and GND pins to your microcontroller's power and ground. The digital output (typically labeled 'S' or 'DO') provides a TTL-level signal that goes LOW when a flame is detected, ideal for simple interrupt or digital read functions. The analog output (labeled 'A' or 'AO') provides a variable voltage corresponding to the infrared intensity, which can be read via an ADC pin for measuring relative flame strength or distance.

The HS-S07A is primarily sensitive to infrared light, which is strongly emitted by flames. However, it can also be triggered by other intense IR sources, such as sunlight, incandescent bulbs, or certain heaters. For reliable flame-specific detection, consider adding optical IR-pass filters, implementing software-based flicker frequency analysis, or using the sensor in controlled lighting conditions.

The sensing range is approximately up to 80 cm, but this is highly dependent on the size and intensity of the flame. A small lighter flame may be detected at a shorter range (20-30 cm), while a larger fire can be detected from farther away. Environmental IR interference and the angle of the sensor also significantly affect the practical detection distance.