Hi everyone. I’m using the Arducam 12MP2 Synchronized Stereo Camera Bundle Kit for Raspberry Pi (two 12.3MP IMX477 modules with CS lenses and the Arducam Camarray stereo HAT) on a Raspberry Pi 4B 4GB. The goal is to do stereo-correlation measurements with several cameras, but the system is pretty unstable. After a while the image turns purple and starts scrolling, but only for one of the two cameras. It works intermittently. I’ve already tried swapping the camera, the Raspberry Pi, the cable, and even the Camarray HAT itself, and none of that fixed it. Any idea what could cause this?
Thanks for the details. Purple scrolling on only one channel is a bit unusual. Could you record a short video of the failure when it happens? That would help a lot. Also let us know how the cameras are connected when you record it, whether that’s directly to the HAT or through any extension/adapters.
Thanks. Here’s more context on the setup. The cameras need to sit inside a vacuum box, and the signal has to pass through the door via SUB-D25 feedthroughs. To get the extra cable length, I’m using the Arducam CSI to HDMI Adapter Board for 12MP IMX477 (the HDMI cable extension module with 15-pin 60mm FPC cables). Here’s a schematic of the setup: 
I’ve been testing two configurations:
Configuration 1 with HQ Raspberry Pi cameras: the image is visible for about a minute, then purple bands appear. Here’s a video of it: Unique Download Link | WeTransfer. The weird part is the same thing happens when I connect the cameras directly to the Camarray HAT with no extension at all. So it seems tied to using Raspberry Pi cameras rather than Arducam cameras.
Configuration 2 with the Arducam cameras: the Raspberry Pi doesn’t see the cameras at all. The Arducam cameras are FPC-22, and I’m using an FPC-22 to FPC-15 cable, which might be blocking the video stream. If I connect the Arducam cameras directly to the Camarray HAT, it works with no problem.
So overall: after a while the image becomes purple and starts scrolling for only one of the two cameras.
Actually, one more question on top of the above. Would it be possible to tie the GNDs together on a custom PCB? I’m thinking of making the same kind of board that converts HDMI to FPC, but with 22 pins instead of 15. The issue is HDMI only has 19 channels, so I can’t pass all 22 signals without combining some of them. Is combining the GNDs feasible?
Thanks for the detailed breakdown and the video, that really helps.
For configuration 1: the Arducam Camarray HAT isn’t really compatible with a standard HQ Raspberry Pi camera. Arducam modified some components on the camera boards that are sold together with the HAT, so the HAT expects those modified boards. That matches what you’re seeing - even plugged directly into the HAT, the HQ Pi camera runs for about a minute and then develops the purple scrolling.
For configuration 2: the Arducam cameras use FPC-22, and the FPC-22 to FPC-15 adapter is very likely preventing the video stream from passing, which is why the Pi doesn’t detect them. You already confirmed they work when connected directly to the HAT.
Can you double-check and confirm that the Arducam camera modules work correctly when connected directly to the Camarray HAT with no extension cable in the path?
Yes, that’s confirmed - the Arducam cameras work fine when plugged directly into the HAT. But I still need to get the signal through the vacuum box feedthroughs. Do you have any ideas where the problem is actually coming from, or any leads I can explore? I’m stuck between the HDMI converter only having 15-pin FPC on one side and the cameras being 22-pin. Any pointers would be appreciated.
Glad the direct connection is confirmed working. For the custom PCB idea about combining the GNDs to make a 22-pin version of the HDMI-to-FPC converter - that’s a customization request rather than standard support. I’ve forwarded your request to our sales team, and they’ll assess whether it’s feasible and what a plan would look like. You can also reach them directly at [email protected] for customization questions.
To summarize where we are: the purple scrolling with the HQ Pi camera happens because that board isn’t the Arducam-modified version the HAT expects, and the Arducam camera detection issue comes from the FPC-22 to FPC-15 adapter blocking the video stream. The custom HDMI-to-FPC-22 board with combined GNDs is now being looked at by sales as a feasibility assessment.