THEIA-CAM MIPI/CSI Camera

THEIA-CAM™ (P/N THSCJ101) is a 13 Mega-Pixel MIPI/CSI camera with Phase Detection Auto Focus from THine Solutions. The THEIA-CAM works with the NVIDIA Jetson Orin Nano and Orin NX. Looky here:

Introduction

Vision processing is one of the most popular applications on NVIDIA Jetson. There are a wide variety of cameras to choose from, certainly good fits for almost any need. There are two main ways to get camera input to the Jetson. The first is through a USB interface. This is now the easiest way to get those tasty pixels in. However, there are overhead and certain constraints in using that method. USB typically has bandwidth constraints which may force the camera to compress images before sending it over the cable. Then there’s the cabling, connectors, and hardware overhead. Plus there’s the extra power needed which may not play well with mobile systems.

On the other hand, there is a more direct route for getting pixels to the processor in embedded systems like the Jetson. MIPI (Mobile Industry Processor Interface) and CSI (Camera Serial Interface) define a standard specification and protocol for communication between a camera module and a host processor.

Faster Development

In this article, we’ll talk about MIPI/CSI. The Jetson Orin Nano and NX carrier boards typically have CSI camera connectors. The connectors accept 22-pin flat flexible cables, which are industry standard for connecting camera sensors to the host processor.

Handling the camera sensor is done through an ISP (Image Signal Processor). Here’s where things get a little tricky. The Jetsons have a ISP block, so some camera modules rely on the internal Jetson ISP. That means that driver code needs to be written for the Jetson. This requires familiarity with the Jetson, and how to implement camera features most efficiently on the Jetson ISP.

On the other hand, some camera module manufacturers place their own ISP on the camera module itself. That’s the case with the THEIA-CAM THSCJ101. The advantage of this approach is that the module manufacturer has control over the sensor module, and can fine tune its performance on its own hardware. That means the camera module has the same performance regardless of the platform on which it is installed.

There’s time to market to consider when creating a new product. Manufacturers which use their own ISP are pretty much ready to go with only a small amount of glue code needed to interface with the host.

Video Four Linux (V4L)

Once the ISP is done processing the pixels from the sensor, the V4L (Video Four Linux) subsystem makes them available to user space. There is usually a V4L2 driver for any given camera sensor, you’ll see this as the familiar /dev/video outputs. V4L2 gives the end user a generic interface for interfacing with camera, regardless of how it is connected to the host system.

For CSI cameras in particular, there are changes to apply to the Jetsons hardware device tree. The device tree specifies the parameters of the camera and control signal locations.

THEIA-CAM THSCJ101

With the explanation out of the way, let’s look at today’s subject. The THEIA-CAM THSCJ101 is a 13 Megapixel Sony IMX258 sensor module with an onboard ISP. This allows the following resolutions and frame rates:

YUYV is an uncompressed pixel format. All the pixel goodness is there to enjoy! The camera CSI-2 supports both MIPI 2 Lane and 4 Lane.

Phase Detection Auto Focus

The THEIA-CAM has (PDAF) Phase Detection Auto Focus, which allows extremely fast autofocusing. There are different autofocus modes available; I found PDAF to be quite exceptional.

Read All About It!

THine Solutions provides a lot of reference material about the camera. Make sure to look through it if you are considering buying this camera. Here are the links:

• THEIA-CAM™ for NVIDIA Jetson Orin™ NX/Nano
• Start Guide PDF Version
• Datasheet
• V4L2 Driver Integration Manual
• V4L2 Command Manual
• THSCU101 Image Quality Report

The Image Quality Report is useful if you want to quantize the performance of the camera. It’s better or equivalent to the camera in an iPhone 12 in several tests. The V4L2 command manual will give you an idea of the flexibility of the camera for your application.

Conclusion

The THEIA-CAM™ (P/N THSCJ101) is certainly a camera to consider if you are developing an application which needs high-resolution imaging. The fine control over the image quality and autofocus speed along with straightforward integration makes it a candidate for very demanding applications.

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