Overview

The RCWL-0516 is a low-cost microwave motion sensor module that utilizes Doppler radar technology to detect moving objects (human beings, pets, vehicles). It operates at a frequency of ~3.18 GHz using an microstrip patch antenna and an RCWL-9196 processing chip.

Unlike Passive Infrared (PIR) sensors (such as the HC-SR501) which rely on thermal infrared heat radiation and line-of-sight vision, the RCWL-0516 can detect movement through thin walls, doors, glass, and plastic enclosures with a 360-degree omnidirectional detection zone up to 7 meters7\text{ meters}.

Quick reference

Operating Voltage (VIN)4.0 V to 28.0 V DC (5.0 V nominal)
Operating Frequency~3.18 GHz (S-band Doppler radar)
Detection Distance5 m to 7 m (omnidirectional spherical pattern)
Detection Angle360 degrees (no blind spots)
Output SignalDigital 3.3V TTL HIGH (held for ~2 seconds upon motion trigger)
Transmitting Power20 mW (typical) / 30 mW (max)
Onboard Regulator (3V3)Provides regulated 3.3V output (up to 100 mA) for external MCUs
Light Sensor Pad (CDS)Solder pads to attach a CdS photoresistor to disable motion detection in daylight

Pinout

Standard 5-Pin Module Header

PinNameTypeDescription
13V3Power OutputRegulated +3.3 V DC output (from internal LDO, up to 100 mA)
2GNDPowerGround (0 V)
3OUTDigital OutputMotion trigger output (Normally 0V, goes 3.3V HIGH for ~2s when motion is detected)
4VINPower InputSupply voltage (+4.0 V to +28.0 V DC)
5CDSControl InputDisable pin (Disable motion output when pulled below 0.7V)

Specifications

ParameterSymbolMinTypMaxUnitConditions
Supply VoltageVINV_{IN}4.05.028.0VDC
Quiescent CurrentICCI_{CC}2.22.83.0mAActive scanning mode
Operating FrequencyfRFf_{RF}3.103.183.30GHzDoppler radar
Output Voltage HighVOHV_{OH}3.23.33.4VOUT=HIGHOUT = HIGH on motion
Output Voltage LowVOLV_{OL}000.1VOUT=LOWOUT = LOW no motion
Trigger Hold Timetdelayt_{delay}1.82.02.5sBase pulse width
Detection Distancedranged_{range}5.07.09.0mLine of sight in open space

Optional Component Modification Pads

The back of the RCWL-0516 PCB contains SMD solder pads for fine-tuning performance:

  • C-TM (Timing Capacitor Pad): Adding a 0805 capacitor lengthens the default 2-second output pulse time (tdelayt_{delay}).
  • R-GN (Gain Resistor Pad): Adding a 1 MΩ1\text{ M}\Omega resistor reduces detection range from 7m to ~5m.
  • R-CDS (Light Sensor Pull-up Pad): Solder a 47 kΩ47\text{ k}\Omega to 100 kΩ100\text{ k}\Omega resistor when adding a CdS LDR to the CDS pin for night-only motion triggering.

Wiring

RCWL-0516 Pin→Microcontroller (Arduino Uno / ESP32)
VIN5V (or 4V–28V external power)
GNDGND
OUTDigital GPIO Pin (e.g. D2 for interrupt reading)
Warning

Placement & False Triggering Guidance:

  • Proximity to Wi-Fi / Bluetooth Routers: High-power 2.4 GHz Wi-Fi signals (such as ESP32 Wi-Fi antennas or home routers placed <1 meter<1\text{ meter} away) can cause continuous false triggers on the 3.18 GHz microwave receiver. Maintain at least 50 cm50\text{ cm} clearance from active Wi-Fi antennas.
  • Metal Shielding: Do NOT enclose the front or back of the sensor inside metal cases. Metal reflects RF microwave signals, creating a total blind spot. Plastic, acrylic, and wood enclosures are transparent to 3.18 GHz microwaves.

Common mistakes

  • Mounting two RCWL-0516 modules next to each other: Placing two active microwave radar sensors within 2 meters of each other causes mutual RF interference and false triggering. Space sensors >3 meters>3\text{ meters} apart.
  • Expectation of static presence detection: Doppler radar detects relative motion (moving objects). An individual standing completely still will eventually stop triggering the Doppler frequency shift output.
  • Expecting line-of-sight boundaries: The radar penetrates thin drywall and glass. Motion in an adjacent room will trigger the sensor unless shielded by metal.

Notes

  • Ideal replacement for PIR sensors in outdoor weather-sealed enclosures where lens condensation or wind heat currents cause false PIR triggers.

Assets & downloads