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HC-SR04 ultrasonic ranging sensor~

This feature is included only in tasmota-sensors binary

When compiling your build add the following to user_config_override.h:

#ifndef USE_SR04
#define USE_SR04                            // Add support for HC-SR04 ultrasonic devices (+1k code)
    #define SR04_MAX_SENSOR_DISTANCE  500   // Set sensor max detection distance    #endif

HC-SR04 (HC-SR04P and JSN-SR04T) is an ultrasonic ranging sensor. Provides 2cm to 300cm of non-contact measurement functionality with a ranging accuracy that can reach up to 3mm. Each HC-SR04 module includes an ultrasonic transmitter, a receiver and a control circuit. See HC-SR04 Ultrasonic Sensor for more information.

Buy example: - AliExpress - Sparkfun

The US-100 can also be use as a HC-SR04 if you remove the jumper at the back (check Adafruit documentation).



Vcc 5V
Trig GPIOx
use voltage divider!

The HC-SR04 operates at 5V and therefore the echo signal will be 5V as well. Connecting the echo pin via a voltage divider (see schematic) will divide the 5V to 3.3V, which is the operating voltage of an ESP8266.

There is a variant of the HC-SR04, called HC-SR04P. It mainly operates at 3.3V and then it doesn't need the voltage divider but you will notice a range drop of about 1 meter. image

Tasmota Settings~

In the Configuration -> Configure Module page assign:

  1. GPIOx to SR04 Tri (69)
  2. GPIOy to SR04 Ech (70)


Tasmota Main~

After a reboot webUI displays the HC-SR04 distance.


Sensor sends a tele/%topic%/SENSOR JSON response: