Banana Pi is releasing the BPI-CM5 Pro, which claims to be electrically and mechanically compatible with the CM4. I am sure driver work would be needed, but otherwise this may be compatible with the current carrier board.
Unlike the A311D this uses an RK3576 and supports 16GB of memory, and has built-in wifi. Seems like a good upgrade if drivers can be sorted.
Anyone with more knowledge willing to look at the docs to see if this is viable? CNX has a link in their article.
It would be nice to get more life out of the CM4/A311D carrier board.
Edit: this uses A72 which is a downgrade in clock speed vs A73, but that should be offset for many tasks by the two extra efficiency cores (4xA53) and the extra ram.
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Here is a screenshot of the CM4 pinout comparison, hopefully it’s legible:
It looks like there are a number of small changes, not sure which if any are relevant or can be worked around in software.
Specs:
- SoC – Rockchip RK3576
- CPU – 4x Cortex-A72 cores at 2.2GHz, 4x Cortex-A53 cores at 1.8GHz
- GPU – Arm Mali-G52 MC3 GPU with support for OpenGL ES 1.1, 2.0, and 3.2, OpenCL up to 2.0, and Vulkan 1.1
- NPU – 6 TOPS (INT8) AI accelerator with support for INT4/INT8/INT16/BF16/TF32 mixed operations.
- VPU
- Video Decoder – H.264, H.265, VP9, AV1, and AVS2 up to 8Kp30 or 4Kp120, MPJEG decoding up to 4Kp60
- Video Encoder – H.264, H.265, (M)JPEG up to 4Kp60
- System Memory – 8 or 16GB 32-bit LPDDR5
- Storage – 32GB, 64GB, or 128GB eMMC flash
- Wireless – WiFi 6 and Bluetooth 5.3 via Synaptics SYN43752 module (That’s more mass production, but the prototypes are based on RTL8852BS)
- Host interface – 2x 100-pin high-density connectors with a pinout mostly compatible with the Raspberry Pi Compute Module 4, but:
- Only supports only 1x HDMI, and 1x MIPI DSI interface instead of 2x for each on the CM4
- Adds an extra 2x PCIe/SATA/USB 3.0 multiplexed interface
- Power Supply
- Supply Voltage – 4.5V to 5.5V DC
- RK806S-5 PMIC
- Dimensions – 55 x 40 mm
- Weight – 12 grams
- Temperature Range – 0°C to 80°C
Block diagram:
Docs and wiki
Most CM4 compatible boards should be mechanically and electrically compatible. Orange Pi, Banana Pi, Pine64, etc. all make modules. I don’t see any immediate red flags for how the the Ornage-Pi CM5 has repurposed some of the pins.
Kernel/driver support is the time consuming part, even though the Banana Pi CM5 is from the same SoM vendor as the A311D/Banana-Pi CM4, it uses a different processor, wifi, uboot, and devicetree. Inevitably different quirks that require debugging and some special casing in drivers as well.
All is theoretically solvable! Someone would have to spend the time to make the support though. I think MNT’s current resources are dedicated to the current modules, the upcoming rk3588 module, and Reform Next. With limited development resources I wouldn’t expect to see official support for other modules unless the community provides them.
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Thanks, this is what I was hoping to learn. I definitely wouldn’t expect MNT’s limited resources to go towards something like this. It’s just hard to know if compatibility is even feasible as someone who isn’t familiar with the way the carrier board interfaces with the mainboard.
The fun part of the MNT Reforms are that the hardware schematics are open source, as well as the software sources.
The RCM4 carrier board - that hypothetically any CM4 compatible module can socket into, and is available in the shop - has its Kicad project files here: Reform / MNT Reform Raspberry Pi CM4 SoM · GitLab
Comparing the pins routed to the module connector, and those used to drive the display through the HDMI->EDP bridge (if needed), to what is available on the Banana-Pi CM5 would be the place to start. Offhand I don’t know if the lack of HDMI1 on this module will be a problem. (edit: looks fine to me, I don’t see anything critically missing for the reform)
