HC-SR04 with Arduino Uno R3

Wiring for the HC-SR04 ultrasonic distance on the Arduino Uno R3 (ATmega328P, 5 V logic), chosen with the same pin rules BoardPilot uses: default buses first, and no pins that are used for flash, USB, the debugger or booting.

Wiring

HC-SR04 pin	Role	Arduino Uno R3 pin	Notes
VCC	Power	5V	Needs 5 V: use 5V
TRIG	Input to the part	2 (PD2)	A 10 µs HIGH pulse starts a measurement
ECHO	Output from the part	~3 (PD3)
GND	Ground	GND

Check before you power it on

Supply: 5 V from the 5V pin.

Test code (Arduino)

void setup() {
  Serial.begin(115200);
  pinMode(2, OUTPUT);  // TRIG on 2
  pinMode(3, INPUT);   // ECHO on ~3
}

void loop() {
  digitalWrite(2, LOW);  delayMicroseconds(2);
  digitalWrite(2, HIGH); delayMicroseconds(10);
  digitalWrite(2, LOW);
  long us = pulseIn(3, HIGH, 30000);
  Serial.println(us / 58.0);  // distance in cm
  delay(200);
}

Arduino board: arduino:avr:uno.

Questions

Which Arduino Uno R3 pins do I use for the HC-SR04?

VCC → 5V, TRIG → 2 (PD2), ECHO → ~3 (PD3), GND → GND.

Does the HC-SR04 work with the Arduino Uno R3 at 5 V?

Yes: the HC-SR04 runs at 5 V and the Arduino Uno R3 uses 5 V signals, so no level shifting is needed.

BoardPilot checks this wiring in 3D as you build it, and finds crossed or missing wires on the real board.

Download BoardPilot

Full Arduino Uno R3 pinout · HC-SR04 ultrasonic distance: all pins and data

The HC-SR04 on other boards

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