In May 2013, the Raspberry Pi Foundation released its original camera module, opening the possibilities for what this little SBC (single-board computer) could do. Since then, much has changed in the world of computing ― Raspberry Pi released several new generations of boards as well as a new camera, the upgraded V2. Other SBCs have also arrived on the market. And while the Coral Edge TPU dev board by Google is a unique device, it shares some features with other cameras.
Evaluating Cross-Compatibility
In this article, we'll focus on the camera modules as opposed to the boards themselves. Let's get this out of the way: while they are very similar in form and function, the Coral Camera and Raspberry Pi Camera are not compatible. First, while both use a MIPI-CSI connector to attach the camera and dev kit/SBC, the Coral's ribbon cable and conductor pads are significantly smaller than the Pi Camera's.
But if these components are smaller, what about using a Pi Zero adapter? You may notice that Pi Zero-adapted Pi camera ribbon cable line up, so I understand the temptation to see if it would work. However, the smaller Pi Zero cable leaves several pins unconnected that are used for the Coral Camera, as you can see in this pinout diagram. Therefore, swapping the two would seem to be impossible without a significant amount of hacking.
When it comes to mounting, the hole pattern for each device is also different, so don't expect to jam a Coral Camera into a Raspberry Pi mounting fixture.
With that bit of disclaimer out of the way, let's explore how these boards stacks up with one another.
Google Coral Camera Specs:
List price:$24.99
Size: 25 x 25 x 7mm
Weight: 3g
Sensor resolution: 5 megapixels
Sensor: OmniVision OV5645
Optical size: 1/4"
Focus: Auto: 10cm-infinity
Raspberry Pi Camera V2 Specs:
List price: $25
Size: 25 x 23 x 9mm
Weight: 3g
Sensor resolution: 8 Megapixels
Sensor: Sony IMX219
Optical size: 1/4"
Focus: Manual 8cm (unverified)-infinity
Interpreting the Device Specs
You'll notice that the list prices are nearly identical, but the Pi Camera V2 features an 8MP resolution, versus the Coral's 5MP spec. The other major difference is that the Coral camera can auto-focus, while the Pi Cam V2 has a manually adjustable focus. Both have their pros and cons depending on your application, so consider which focus is best for you.
Another item to consider is that there is a wide range of unofficial RPi cameras with differing capabilities, as well as an official NoIR camera for night use. The ecosystem for the Coral Camera is, as a very new product, extremely limited. As with hardware, it's easier to find use examples for the Picamera at this point.
Other Options
On the other hand, both the Coral TPU dev board and the Raspberry Pi can use USB cameras, giving both a wide range of alternatives. If you want a specific camera with the Coral TPU, another option would be to use a Raspberry Pi with a Coral TPU accelerator. You could even consider the Jetson Nano, which pairs well with the Raspberry Pi camera.
While the Coral Camera and TPU boards are still in their infancy, I'm interested to see how people use them and their corresponding camera. Both the Coral Camera and the Raspberry Pi cameras have appropriate use cases, and there is always the webcam option if needed.