HC-SR04 with Raspberry Pi Pico 2

Wiring for the HC-SR04 ultrasonic distance on the Raspberry Pi Pico 2 (RP2350, 3.3 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	Raspberry Pi Pico 2 pin	Notes
VCC	Power	VBUS	Needs 5 V: use VBUS
TRIG	Input to the part	GP15	A 10 µs HIGH pulse starts a measurement
ECHO	Output from the part	GP14
GND	Ground	GND

Check before you power it on

Supply: 5 V from the VBUS pin.
The HC-SR04 works at 5 V. On the Raspberry Pi Pico 2, GP14 tolerate 5 V inputs, so a direct connection is fine while the board is powered.

Test code (Arduino)

void setup() {
  Serial.begin(115200);
  pinMode(15, OUTPUT);  // TRIG on GP15
  pinMode(14, INPUT);   // ECHO on GP14
}

void loop() {
  digitalWrite(15, LOW);  delayMicroseconds(2);
  digitalWrite(15, HIGH); delayMicroseconds(10);
  digitalWrite(15, LOW);
  long us = pulseIn(14, HIGH, 30000);
  Serial.println(us / 58.0);  // distance in cm
  delay(200);
}

Arduino board: rp2040:rp2040:rpipico2. If the board is not found, hold the BOOTSEL button while plugging in the USB cable.

Questions

Which Raspberry Pi Pico 2 pins do I use for the HC-SR04?

VCC → VBUS, TRIG → GP15, ECHO → GP14, GND → GND.

Does the HC-SR04 work with the Raspberry Pi Pico 2 at 3.3 V?

Yes: the HC-SR04 runs at 5 V and the Raspberry Pi Pico 2 uses 3.3 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 Raspberry Pi Pico 2 pinout · HC-SR04 ultrasonic distance: all pins and data

The HC-SR04 on other boards

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