I’m trying to get my UC-625 Stereo HAT (part of the B0195 kit) working with two OV5647 cameras on a Raspberry Pi 4 Model B (2GB). I’m running Raspberry Pi OS Bullseye 32-bit Legacy, but neither camera is detected. When I run vcgencmd get_camera, I get: supported=1 detected=0. I’ve already tried downloading multiple drivers and even attempted to remove libcamera files but that didn’t help either. Any ideas?
Let’s start with the basics. Could you confirm the exact OS version you’re running and let me know what you tried regarding the libcamera removal? I ask because the UC-625 HAT is a legacy product that originally relied on the old proprietary camera stack (raspistill/raspivid). Bullseye ships with libcamera by default, and simply removing libcamera files won’t revert the underlying kernel drivers — they’re designed to work with the new framework. Also, have you tried using an older OS like Buster to see if the cameras work with the legacy stack?
That makes sense. I did try downgrading to Buster. First I flashed the 2021-01-11-raspios-buster-armhf image, but the Pi 4 wouldn’t boot — it just showed “This board requires newer software”. I’m guessing my bootloader is too new? vcgencmd bootloader_version shows 2026/02/06 (version 8124798b). I then tried the 2021-05-07-raspios-buster-armhf image and that booted fine. After booting, vcgencmd get_camera now shows supported=1 detected=1 and both cameras are detected via the UC-625 HAT! But now I’m stuck on the driver side.
Good progress! So Buster is working and the cameras are detected — that’s a solid step forward. What kernel version does that Buster image ship with? And what issue are you hitting with the driver? Are you working with the Arducam_OBISP_MIPI_Camera_Module repository?
Right, I cloned the Arducam_OBISP_MIPI_Camera_Module repo. The kernel is 5.10.17-v7l+. When I checked for a pre-built OBISP driver, the highest available is for kernel 5.4.83-v7l+ — nothing for 5.10.17. So I tried running build_driver.sh to compile from source, but it fails with HTTP 404 errors when trying to fetch build dependencies. So my questions are:
(1) Is there a pre-built OBISP driver for 5.10.17-v7l+ available?
(2) Can I force-load the 5.4.83-v7l+ driver on 5.10.17?
(3) Can I downgrade the kernel on Buster without breaking apt?
(4) Is there any alternative setup path for the UC-625 with a newer bootloader?
Great questions. Let me break it down:
- Pre-built driver for 5.10.17: No, the repo doesn’t have one for that kernel. You’d have to build from source, which brings us to…
- Force-load 5.4.83 driver on 5.10.17: Not recommended — kernel modules are compiled against specific kernel versions and will likely crash or refuse to load.
- Downgrading kernel on Buster: Risky. You could manually swap kernels but apt will fight you on it. Not a clean path.
- Alternative setup: Here’s the core issue — the UC-625 HAT is a very early generation multi-camera adapter from the B0195 kit. It relies entirely on the old proprietary Arducam OBISP library and the legacy raspistill stack. On Buster this works fine, and since you’ve got Buster booting with cameras detected, you’re actually in good shape!
The solution: Stick with Raspberry Pi OS Legacy (Buster) and follow the install instructions directly from the GitHub repo instead of trying to build from source manually. The instructions are here: GitHub - ArduCAM/Arducam_OBISP_MIPI_Camera_Module · GitHub
That repo uses the old raspistill-based library to control camera switching, which is exactly what the UC-625 needs. The 5.10.17 kernel on that Buster image should be fine with the right installation steps from the README.
Key insight: The UC-625 HAT is fundamentally incompatible with Bullseye’s libcamera stack. There’s no workaround — the kernel drivers on Bullseye+ are designed for the new framework and you can’t force the old proprietary stack onto them. Your only option is Buster, which you already have booting.
That said, if you ever want to move to a modern OS, consider upgrading to a fully-supported multi-camera solution like the Arducam CamArray HAT, which works with Bullseye, Bookworm, and the libcamera stack natively.