Radar Proximity Sensor (RCWL-0516)

Summary

The RCWL-0516 sensor uses a microwave Doppler radar to detect moving objects and thus trigger a proximity alert. Doppler Radar makes use of the Doppler Effect, a phenomenon discovered in 1842 by the Austrian physicist Christian Doppler. The Doppler Effect describes a change in frequency observed by a stationary observer when the source of the frequency is moving. Device operates at ~3.2GHz/20 - 30mW. The device has a sensitivity range of ~7 meters. When triggered its trigger output pin will switch from (LOW) 0V to high (3.3V) for ~ 2 to 3 seconds before returning to its idle LOW state. The device does not measure the distance to the detected object or its velocity, just its presence.

Component side should face detection area for maximum sensitivity. Do not place metal objects within 1cm of antenna. Trigger out - HIGH (3.3V) motion / LOW no motion. Note that the 3V3 pin is a 3.3-volt output, not a power supply input. The device has an integrated 3.3 volt voltage regulator which can provide up to 100 mA of current for powering external logic circuitry.

The VIN pin is the positive power supply input, accepting any voltage from 4-volts to 28-volts. The RCWL-0516 does not consume very much current and can easily be powered by the 5-volt output from an Arduino or a Raspberry Pi. This device does not consume much current and operates within the range of 4 to 28 volts, making it useful for a battery-powered design. The microwave antennas are integrated onto the small printed circuit board, making it a self-contained unit.

The RCWL-0516 also support an optional cadmium disulphide light-dependent resistor (LDR) to allow the device to operate only in darkness. This can be very useful in light control applications. The light dependent resistor (LDR) can be attached to the “CDS” pins. The LDR can actually be hooked up two ways: (i) Using the two CDS pads on the top of the sensor printed circuit board. (ii) By connecting one end to the CDS pin on the main terminal section and the other end of the LDR to ground. The light sensor will disable the device when it detects ambient light. You may also use the CDS pin as an Enable control for the module.

Pin 9 is pulled up (=output enable) by a 1M resistor. Attaching the optional CDS LDR will pull pin 9 down (=output disable) when it is light (i.e. the LDR's resistance drops below ~269k assuming no resistor R-CDS installed). R-CDS allows you to add a resistance in parallel with the onboard 1M pullup to adjust the light level at which pin 9 is pulled <0.7V.

RCWL-0516 Key Features

Transmit power: 20 mW (minimum)/30 mW (max)
Voltage input: 4–28 VDC
Sensing Distance: 5–7 m
Frequency of sensor: ~3.2 GHz

How to Connect

To connect to the Grove board:

Solder pins to the RCWL-0516 board
Connect left-most wire (GND) to GND pin on module
Connect the second-left wire (VCC) to VIN pin on module
Connect the right-most wire (D2) to OUT pin on module

RCWL-0516 Pinout

VIN — 4V - 28V DC power supply input
CDS — Sensor disable input (low = disable) (For LDR sensors)
GND — Ground
3volt— DC output (100 mA maximum)
OUTPUT — HIGH /LOW(3.3 V) (according to the motion detection)

How to use in XOD

Use the the digital-read node from the xod/gpio library. The SIG output pin will read ‘true’ if movement has been detected and ‘false’ if not.

Test patch:

Set port to D2 (or whichever port you are using) and UPD to ‘Continuously’. Connect SIG to a watch node, or to an led node to get a visual output. Upload and debug.