This week’s EYE ON NPI (video) is sixty-giga-cool with 60 giga-Hertz of Doppler radar sensing. It’s the Infineon XENSIV™ BGT60LTR11AIP Radar and Shield2Go Dev board, featuring Infineon’s super-low-power 60 GHz Doppler radar sensor with antenna-in-package (AIP).

This device is an ultra-tiny 60 GHz radar-on-a-chip sensor that even includes the normally-large antenna’s seen in most Doppler radars baked right into the top!

RADAR is literally “Radio Detection And Ranging” – a way of bouncing ‘high frequency’ electromagnetic waves off of objects to detect the reflection. We’re familiar with radar in a few contexts: originally developed for military use, it worked great for detecting metal things in the sky (airplanes) as they would approach a city to possibly bomb it.

We still use it a lot in military contexts: detecting planes, bombs, boats and submarines. It’s also super handy in domestic contexts like air traffic control, if you can detect planes you can verify their positions and make sure each one comes in or out of the airport without collision. Radar is also useful for weather pattern detection (although this sensor isn’t good for that purpose, just a fun fact for you to know).

Another common purpose for radar you’re probably familiar with is the dreaded speeding radar gun, a small-enough-to-be-handheld radar device that can be pointed at a car to determine its speed without requiring a difficult-to-calculate “time between two points” measurement. These reliable devices are apparently now are replaced with LIDAR based ones!

Most folks who have used IR sensors, Time of Flight, or sonar sensors can understand how to detect an object by counting the delay between sending a signal vs when it’s received and dividing by the wavelength. How can you determine velocity – normally you’d need to detect location twice, then determine the time between the two locations whereas radar can do it one measurement. This is thanks to the ‘Doppler Effect‘, the same scientific principle that causes ambulance sirens to be higher pitch as they approach and lower pitch as they drive away from you due to the ‘bunching up’ of the waves as the wave source moves. Likewise with Radar, the frequency will shift slightly depending on the speed of the object, which can be detected by calculating the minute variation in frequency.

While radar sensors can be used for detecting speed, they’re becoming more popular as a way to detect humans. Normally folks would be using a PIR sensor for that, as they’re low cost, and fairly simple: when motion is detected, a pin toggles. There are some benefits of radar for motion/person detection, documented by Infineon here.

Most common benefits are: radar modules can be hidden behind an opaque material as long as it’s 60GHz-transparent, directionality of motion is detectable so you can tell if someone is moving towards or away from the sensor, fast response, smaller size, and wide-angle vision. However, the pricing is going to be higher than PIR – so it’s best used when the application can take advantage of those benefits.

What’s particularly neat about this sensor is that, compared to other radar modules that have a trace PCB antenna, the antenna is embedded right into the chip itself. Compare that with the BGT24 modules that come on a PCB with an ‘Arduino shield size’ antenna.

The BGT60LTR11AIP comes as a BGA component, with a lot of pins! Thankfully, Ultra Librarian has a package footprint for this part that Digi-Key helpfully provides, so you can import and get started with integration quickly.

There’s also a few different development boards available, including a tiny module ‘shield’ SHIELDBGT60LTR11AIPTOBO1 that requires only 4 pins: power, ground, output direction and output motion detect.

There’s also a fancy “SHIELD2GO” board that has all of the user-useful GPIO and SPI interface accessible, and a full demo dev kit that also includes the mini shield.

There are two ways to integrate the sensor: via simple two-GPIO connection where one pin is motion detect and the other is direction, or via a more complex SPI protocol.

The SPI interface is documented in the User’s Guide and the Infineon bgt60 GitHub repo has some portable C code that just needs a hardware abstraction layer implemented in order to be used with your favorite platform.

For an ultra-tiny Radar module-on-a-chip that has low-power, low-cost and ease-of-integration, you can pick up the Infineon XENSIV™ BGT60LTR11AIP at Digi-Key. It’s in stock right now for immediate shipment, and available in any quantity on cut-tape or reel: order today and you can be Dopplering by tomorrow afternoon.