HC-SR501 PIR with Raspberry Pi Pico W

Wiring for the HC-SR501 PIR motion sensor on the Raspberry Pi Pico W (RP2040, 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

Check before you power it on

• Supply: 5 V from the VBUS pin.
• The HC-SR501 PIR works at 5 V, so its output (OUT → GP15) can reach 5 V. The Raspberry Pi Pico W pins take only 3.3 V: add a voltage divider (for example 1 kΩ and 2 kΩ) or a level shifter on that wire.

Test code (Arduino)

void setup() {
  Serial.begin(115200);
  pinMode(15, INPUT);  // OUT on GP15
}

void loop() {
  Serial.println(digitalRead(15));
  delay(100);
}

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

Questions

Which Raspberry Pi Pico W pins do I use for the HC-SR501 PIR?

VCC → VBUS, OUT → GP15, GND → GND.

Does the HC-SR501 PIR work with the Raspberry Pi Pico W at 3.3 V?

The HC-SR501 PIR works at 5 V, so its output (OUT → GP15) can reach 5 V. The Raspberry Pi Pico W pins take only 3.3 V: add a voltage divider (for example 1 kΩ and 2 kΩ) or a level shifter on that wire.

Full Raspberry Pi Pico W pinout · HC-SR501 PIR motion sensor: all pins and data

The HC-SR501 PIR on other boards

ESP32 DevKit Arduino Mega 2560 R3 Arduino Nano Arduino Uno R3 WeAct Black Pill STM32F411CE ESP32-C3-DevKitM-1 ESP32-S3-DevKitC-1 Nordic nRF52840 DK NUCLEO-F401RE Raspberry Pi Pico 2 Raspberry Pi Pico Teensy 4.1

Other parts on the Raspberry Pi Pico W

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