HC-SR501 PIR with Raspberry Pi Pico

Wiring for the HC-SR501 PIR motion sensor on the Raspberry Pi Pico (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 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:rpipico. If the board is not found, hold the BOOTSEL button while plugging in the USB cable.

Questions

Which Raspberry Pi Pico 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 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 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 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 W Teensy 4.1

Other parts on the Raspberry Pi Pico

BME280 BMP280 DHT22 DHT11 HC-SR04 SSD1306 OLED MPU6050 DS18B20 WS2812B LED strip SG90 servo Relay module LCD 1602 I2C INA219 VL53L0X BH1750 MAX30102 RC522 RFID NEO-6M GPS Capacitive soil moisture sensor ADS1115 TM1637 28BYJ-48 stepper L298N Potentiometer Push button LED Joystick module SD card module AHT20