// distance
HC-SR04
Ultrasonic distance sensor
€2.46
avg eur
GPIO trigger/echo
Pins
4
Specs
4
Libraries
2
Protocols
1
// wiring → esp32 devkit v1
3V3
EN
GPIO36
VP
GPIO39
VN
GPIO34
GPIO35
GPIO32
GPIO33
GPIO25
GPIO26
GPIO27
GPIO14
GPIO12
GND
GND
GPIO13
ESP32
WROOM-32
devkit v1
USB
VIN
5V
VCC
GND
GPIO23
GPIO22
SCL
GPIO1
TX0
GPIO3
RX0
GPIO21
SDA
GPIO19
MISO
GPIO18
SCK
ECHO
GPIO5
SS
TRIG
GPIO17
TX2
GPIO16
RX2
GPIO4
GPIO2
GPIO15
sensor pin (left)
sensor pin (right)
unused
// pinout → esp32
| Sensor Pin | ESP32 Connection |
|---|---|
| VCC | 5V (VIN) |
| TRIG | GPIO 5 |
| ECHO | GPIO 18 (via divider) |
| GND | GND |
// technical specs
Range
2–400 cm
Accuracy
±3 mm
Voltage
5V (echo needs divider)
Beam
~15°
// github libraries
// notes & warnings
ECHO is 5V — must use voltage divider (1kΩ + 2kΩ) to drop to 3.3V before ESP32 GPIO.
// related sensors · distance
Submitted by caio.ricciuti@outlook.com
· Apr 26, 2026