RCWL-0516 with a Raspberry Pi Pico
RCWL-0516 is a low-cost microwave Doppler radar motion sensor that outputs a simple digital HIGH when it detects movement, with no infrared optics required.
The RCWL-0516 radar takes its VIN from the Raspberry Pi Pico's VBUS and drives OUT straight into GP0. Its output is a 3.3 V logic level from its own regulator, so unlike most 5 V-powered modules it needs no divider on the Pico.
Wiring the RCWL-0516 to the Raspberry Pi Pico
Pin by pin.
| RCWL-0516 | Raspberry Pi Pico |
|---|---|
| VIN | VBUS |
| OUT | GP0 |
| GND | GND |
- VIN is on VBUS, which gives about 5 V only while the board is powered from USB.
What to know on the Raspberry Pi Pico
- VIN accepts 4 V to 28 V. On the Pico that means VBUS, which is 5 V only while USB powers the board and 0 V otherwise.SparkFun RCWL-0516 product specifications; Raspberry Pi Pico datasheet, release 21, p. 8
- Running the Pico from a single lithium cell on VSYS leaves VBUS at 0 V, and a single lithium cell, about 3.0 V to 4.2 V, sits mostly below the radar's 4 V minimum; give VIN a 5 V source.Raspberry Pi Pico datasheet, release 21, pp. 8, 21; SparkFun RCWL-0516 product specifications
- OUT idles low and drives to 3.3 V for about 2 seconds after motion, within the Pico's GPIO level; the module draws about 2.7 mA.SparkFun RCWL-0516 product specifications
- Its 3V3 pin is the module's regulator output, not an input; leave it and CDS unconnected.SparkFun RCWL-0516 product page, pin description
RCWL-0516 code for the Raspberry Pi Pico
Compiled for rp2040:rp2040:rpipico on 2026-10-29.
// RCWL-0516 on Raspberry Pi Pico: wiring and a free simulation at https://www.tinkered.ai/components/rcwl-0516/raspberry-pi-pico
const int RADAR_OUT = 0; // RCWL-0516 OUT
void setup() {
Serial.begin(9600);
pinMode(RADAR_OUT, INPUT);
}
void loop() {
int motion = digitalRead(RADAR_OUT);
Serial.println(motion == HIGH ? "Motion detected" : "No motion");
delay(200);
}
RCWL-0516 on the Raspberry Pi Pico: questions
Does the RCWL-0516 need a level shifter on a Pico?
No. OUT drives to 3.3 V (SparkFun specifications), the Pico's own logic level, even with VIN on 5 V.
Can the Pico power the RCWL-0516 from 3V3?
No: VIN needs 4 V to 28 V (SparkFun specifications). Use VBUS on USB, or another supply in range.
Can the RCWL-0516 wake a battery Pico?
Its OUT can trigger a GPIO interrupt, but it needs 4 V or more on VIN, so the battery must supply that, for example through a 5 V boost.
Keep going
This guide as plain Markdown. /components/rcwl-0516/raspberry-pi-pico.md