FAQ

Compute Module Compatibility

Can I use a Raspberry Pi CM5?

Yes, with limitations. The Raspberry Pi CM5 is compatible with the Interceptor Carrier Board, but USB boot is not supported.

Why: The Interceptor Carrier Board uses USB 2.0 ports. The CM5 only enables boot capability on USB 3.0 ports.

Solutions:

1. SD Card Boot: If your CM5 has a blank eMMC (never written to), it will automatically try to boot from the SD card slot
2. eMMC Boot: If your CM5’s eMMC has been initialized, you must flash the OS to the eMMC using:
   • A separate Raspberry Pi IO Board (CM4 IO Board or CM5 IO Board both work)
   • The rpiboot utility to expose the eMMC as a mass storage device
   • Your favorite imaging tool (Raspberry Pi Imager, dd, etc.)

Also note: the front panel power button (J2) cannot power the board on with a CM5, because the CM5 moves power-on to a pin the button does not drive. See Power button with CM5 for details and workarounds.

Can I use a Raspberry Pi CM4?

Yes, fully supported! The CM4 works well with the Interceptor Carrier Board.

Boot options:

• eMMC variants: Flash via USB boot using rpiboot
• Lite variants (no eMMC): Boot from SD card or USB drive
• USB boot: Supported for installation

Can I use a “Lite” CM4 without an SD card?

Yes! With a Lite CM4 (no eMMC), you can:

1. Live Mode - Boot and run entirely from a USB flash drive without installing
2. Install to USB - Install the OS to the same USB flash drive for persistent storage
3. Install to SATA - Install the OS to an HDD/SSD connected via SATA

The Exaviz OS installer offers all these options when you boot from the USB installer.

Can I use a Radxa CM4 or CM5?

No. Radxa CM4 and CM5 modules are not compatible with the Interceptor Carrier Board despite their similar form factor.

Only these compute modules are supported:

• ✅ Raspberry Pi CM4
• ✅ Raspberry Pi CM5
• ✅ Banana Pi CM4

Can I use a Banana Pi CM4?

Yes! The Banana Pi CM4 is compatible and offers a compelling advantage: its built-in NPU (Neural Processing Unit) for AI/ML inference workloads. This makes it ideal for applications like object detection, video analytics, and edge AI.

Compatibility:

Why choose Banana Pi CM4?

• Built-in NPU for AI/ML workloads (object detection, video analytics)
• Often more available than Raspberry Pi CM4/CM5
• Good value for AI-focused projects

NPU:

• The Banana Pi CM4 is built on the Amlogic A311D (4x Cortex-A73 + 2x Cortex-A53). Banana Pi rates its NPU at 5 TOPS.
• Banana Pi CM4 Wiki - Hardware documentation

Limitations: HDMI1 and power button not supported. Connect your monitor to J4 (HDMI0).

The power button limitation is a module difference, not a board fault: Banana Pi’s published pinout leaves the enable pin the Raspberry Pi CM4 uses unconnected, so the button has nothing to act on. It is unrelated to the separate CM5 limitation.

CM5 Performance Tip: PCIe Gen 3 (Experimental)

The Raspberry Pi CM5 is officially rated for PCIe Gen 2 (~500 MB/s), but the hardware can run at PCIe Gen 3 (~1000 MB/s) - potentially doubling your SATA bandwidth.

To try PCIe Gen 3 on CM5:

Add this line to /boot/firmware/config.txt:

dtparam=pciex1_gen=3

Then reboot. Verify the link speed with:

sudo lspci -vv | grep -i "lnksta"
# Look for "Speed 8GT/s" (Gen 3) vs "Speed 5GT/s" (Gen 2)

Why you might try it:

• NAS with 5 drives: Gen 2 can bottleneck when multiple drives are active
• NVR with many cameras: Higher throughput for simultaneous recording/playback
• Heavy RAID workloads: Software RAID 5/6 benefits from the extra bandwidth

Real-world results:

• Many users (including Jeff Geerling) report stable Gen 3 performance with significant speed gains
• Others experience errors, crashes, or reduced speeds depending on their specific hardware
• If you see issues, simply remove the line and revert to Gen 2

Note: CM4 and Banana Pi CM4 are limited to PCIe Gen 2 in hardware and cannot be upgraded. This is a CM5-specific option.

Resources:

• Jeff Geerling’s Gen 3 Testing
• Pi PCIe Device Database

What CM4/CM5 variants work best?

Any variant works. Here are the trade-offs:

Storage options:

• With eMMC: Faster boot and I/O performance, more reliable for heavy write workloads
• With SD card (Lite/no-eMMC): Easier to flash OS images, swappable if storage fails (no need to replace entire CM), preferred by many makers and enthusiasts
• CM5 note: Cannot boot from USB, so eMMC or SD card is required

Connectivity:

• With WiFi: Useful for initial setup, but wired Ethernet is recommended for production use

Storage & Boot Options

Does the board have an SD Card slot?

Yes. The Interceptor Carrier Board (v2.0) features a Micro SD Card slot (labeled U18).

SD Card boot compatibility:

• ✅ Raspberry Pi CM4 Lite (no eMMC)
• ✅ Raspberry Pi CM5 with blank eMMC
• ✅ All Banana Pi CM4 variants
• ❌ CM5 with initialized eMMC (cannot force SD boot)

Can I boot from a USB drive?

Can I use the Interceptor as a USB device (gadget mode)?

Not as shipped. On both CM4 Interceptors we tested (Rev 1.0 and Rev 1.1), /sys/class/udc is empty, so no USB device controller is registered and the gadget framework has nothing to attach to. Ethernet, serial and mass-storage gadgets are therefore unavailable in the shipped configuration.

The relevant settings are in /boot/firmware/config.txt:

otg_mode is a Raspberry Pi setting, not an Exaviz one. The two defaults differ, which is worth keeping straight: the firmware default is otg_mode=0, but the Raspberry Pi OS image ships a config.txt that sets otg_mode=1 on Compute Module 4. So a CM4 arrives in host mode before Exaviz software touches it. See the Raspberry Pi config.txt boot options documentation, under otg_mode.

If you remove otg_mode=1 to get the legacy controller back, the change will not survive an update. The exaviz-dkms package rewrites the whole [cm4] and [cm5] sections of config.txt when it installs, so your edit is replaced the next time the package updates. This is also why the section on an Exaviz board does not carry Raspberry Pi’s usual explanatory comment next to otg_mode: the stock section has been regenerated.

We do not test the board with these settings changed.

Does the board support boot from SATA?

Not directly. The Raspberry Pi firmware does not support booting directly from SATA.

Workaround: You can configure a hybrid boot setup:

1. Keep the /boot partition on eMMC or SD card
2. Mount the root filesystem (/) from a SATA drive
3. Edit cmdline.txt to point to the SATA partition:

   root=/dev/sda1 rootfstype=ext4 ...
   

For “Lite” Compute Modules (without eMMC), a USB flash drive or SD card must remain connected to hold the boot files.

What RAID levels are supported?

The JMB585 SATA controller supports software RAID via mdadm:

• RAID 0 (striping)
• RAID 1 (mirroring)
• RAID 5 (striping with parity)
• RAID 6 (striping with dual parity)
• RAID 10 (mirrored stripes)

Hardware RAID is not supported; all RAID is handled in software.

How many drives can I connect?

5 SATA drives maximum (connectors J11-J15).

PoE

How do I power the PoE boards?

You cannot power the PoE boards solely through the motherboard traces. You must install the VOITA 48Vdc Power Converter.

Wiring:

1. Connect VOITA input to the CPU 4+4 pin connector of your ATX power supply (12V)
2. Connect VOITA output to the green terminal block on the first PoE board

How do I control PoE power?

The ip link set poeX up/down command only controls the data link, not the actual power output.

To control power (turn ports on/off), use the /proc/pse interface:

# Disable port 3 on board 0
echo "disable-port 0 3" > /proc/pse

# Enable port 3 on board 0
echo "enable-port 0 3" > /proc/pse

# Check status of all ports (streams continuously, Ctrl+C to stop)
cat /proc/pse

Requirement: OS image dated 2025-05-01 or newer (2025-04-30 for Banana Pi).

How do I change PoE mode (802.3af vs 802.3at)?

By default, ports are configured for 802.3at (PoE+, 30W). To limit a port to 802.3af (15.4W), use:

echo "set-af-mode <board> <port>" > /proc/pse

Example:

# Set port 2 on board 0 to AF mode (15.4W max)
echo "set-af-mode 0 2" > /proc/pse

To switch a port back to 802.3at (30W):

echo "set-at-mode <board> <port>" > /proc/pse

How many PoE ports can I have?

• Single PoE board: 8 ports (via J9 or J10)
• Dual PoE boards: 16 ports (via J9 and J10)

What PoE standard is supported?

• 802.3at (PoE+): Up to 30W per port (default)
• 802.3af (PoE): Up to 15.4W per port (configurable)

Cooling

Can I control fan speed?

No. The four fan headers (M1-M4) are standard 3-pin 12V connectors. They do not support PWM speed control. Connected fans will run at full speed.

Alternatives:

• Use quiet/low-noise fans
• Use an external PWM fan controller
• Use a fan with built-in thermal control

Software & OS

What bootloader settings are recommended?

For CM4, we recommend the following bootloader EEPROM configuration for optimal power management:

POWER_OFF_ON_HALT=1
WAKE_ON_GPIO=0
BOOT_ORDER=0xf215

What these do:

• POWER_OFF_ON_HALT=1 - Enables proper power-off when you run shutdown or halt
• WAKE_ON_GPIO=0 - Disables wake-on-GPIO (prevents spurious wake-ups)
• BOOT_ORDER=0xf215 - Boot order. BOOT_ORDER is read right to left: the lowest nibble is tried first. 5 is BCM-USB-MSD, 1 is SD/eMMC (one mode, not two), 2 is network, f restarts the loop. The USB digit here is 5 (BCM-USB-MSD), not 4 (USB-MSD), and that is deliberate. Digit 4 boots from a USB controller on the PCIe bus; on the Interceptor that lane carries the JMicron JMB58x SATA controller, and the board’s USB comes from the CM4’s own USB 2.0 host, which is what 5 selects. If you need to boot from a USB drive, see Can I boot from a USB drive?.

What OS should I use?

Use standard Raspberry Pi OS (64-bit, Bookworm or newer) with the Exaviz Debian packages installed from apt.exaviz.com. This is the recommended and fully supported path. See the Software page for package installation instructions.

Other compatible distributions:

• Raspberry Pi OS, Debian Bookworm/Trixie (recommended)
• Ubuntu Server: SATA and Ethernet work out of the box; install Exaviz packages for PoE control

Why does apt upgrade fail with a raspi-firmware error?

OS: Raspberry Pi OS Trixie (Debian 13) or earlier (including Bookworm)

Issue: apt upgrade fails with:

Error: missing /boot/firmware, did you forget to mount it?

This occurs because the raspi-firmware package expects /boot/firmware to be a mount point, but on Interceptor systems it’s a regular directory.

Fix:

# Bind mount /boot/firmware to itself (makes it appear as a mount point)
sudo mount --bind /boot/firmware /boot/firmware

# Configure the package
sudo dpkg --configure -a

# Now apt upgrade should work
sudo apt upgrade

The bind mount persists until reboot.

Can I use Windows?

Windows IoT is not supported. The Interceptor is designed for Linux only (specifically Debian/Raspbian-based distributions).

However, you can use a Windows PC to flash OS images:

Recommended tools:

• Raspberry Pi Imager
• Balena Etcher

Known Windows flashing issues: Some users report problems when using Windows to flash Exaviz OS images to a USB flash drive, then attempting to boot the Interceptor from that drive. Errors like “GPT no bootable partition” may occur (while standard Raspberry Pi OS images work fine).

Workarounds:

1. Flash to SD card or eMMC instead of USB flash drive
2. Try flashing from Linux or macOS
3. Use a different flashing tool (Raspberry Pi Imager, Balena Etcher)

What keyboard shortcuts are available in the desktop?

The Exaviz OS uses Wayfire, a 3D Wayland compositor. These shortcuts are available:

How do I scale the display for 4K monitors?

With a 4K monitor, text and UI elements may appear very small. You can increase the display scale in the Wayfire compositor configuration.

Edit ~/.config/wayfire.ini and add:

[output:HDMI-A-1]
scale = 1.5

Or for the second HDMI output:

[output:HDMI-A-2]
scale = 1.5

Common scale values:

• 1.0 - Native (no scaling)
• 1.5 - 150% (good for 4K on 27-32" monitors)
• 2.0 - 200% (good for 4K on smaller monitors)

For more Wayfire configuration options, see the Wayfire Wiki.

How do I access the serial console?

1. Connect a 3.3V USB-to-Serial adapter to J2:
   • Adapter TX → J2 Pin 6 (RX)
   • Adapter RX → J2 Pin 5 (TX)
   • Adapter GND → J2 Pin 7 or 8
2. Use serial terminal settings: 115200 8N1
3. Power on the board

Power

What PSU do I need?

Any standard ATX PSU with a 24-pin (or 20-pin) connector. Key requirements:

• Stable +3.3V rail (critical!)
• Minimum 270W for basic configuration
• 350W+ if using PoE boards
• Flex ATX PSUs (270W, 350W) available in the Exaviz Store

PSUs with Reliable +3.3V Rail (Verified by Exaviz):

PSUs Known to Have Issues:

These PSUs may work in other systems but can cause random crashes or failure to boot with the Interceptor due to its low power draw.

Why does my system crash randomly?

Most likely cause: Unstable +3.3V rail from PSU.

Low-quality or older PSUs often cannot maintain proper 3.3V voltage under the low-load conditions typical of Raspberry Pi systems. Some PSUs also have Under Voltage Protection (UVP) that can trigger even with small voltage drops, shutting down the system.

Symptoms:

• PSU fan spins briefly then stops
• USB devices don’t work
• System powers off after a few seconds
• Random crashes or reboots

Diagnosis: Use a digital multimeter (DMM) to monitor the 3.3V rail while the system is running. Watch for voltage drops below 3.2V (more than 5% below nominal).

Solution: Use a PSU from the verified list above, or any quality modern PSU with a stable 3.3V rail.

What happens after a power outage?

If the system is powered on and experiences a power loss, it will automatically boot back into the OS when power is restored.

On CM4, the front panel power button (connected to J2) is used to power on the system after a manual shutdown (e.g., shutdown -h now), when the PSU is still switched on. On CM5, the button cannot power the system on - see Power button with CM5.

Summary:

• Power loss while running → Auto-boots when power returns
• Manual shutdown (CM4) → Use power button to restart
• Manual shutdown (CM5) → Cycle the PSU switch, or use Wake-on-LAN / remote power
• PSU switched off → System stays off until PSU is switched on

Does the power button work with CM5?

No. The front panel power button (J2) will not power the board on when a Raspberry Pi CM5 is fitted.

The CM4 datasheet gives the restart path the button relies on: hold GLOBAL_EN low briefly and the power system restarts after a software shutdown. The CM5 documents that pin as power-off only, and moves power-on to a separate pin the button does not drive.

Workarounds:

• Cycle the PSU switch to power the board on and off
• Soft shutdown from the OS (shutdown -h now) followed by a PSU cycle to restart
• Wake-on-LAN or remote management for headless deployments
• Use a CM4 if physical power button control is required

If a power button misbehaves on a CM4, that is not this limitation: check the front panel wiring and the switch itself. We do not recommend modifying the board to work around the CM5 case, and it is not supported.

This is a CM5 design limitation, not a defect of the Interceptor. The power LED on J2 continues to work normally.

If you have made a CM5 power button work on an Interceptor, we would like to hear how. Write to info@exaviz.com.

Identification

Where can I find the serial number or MAC address?

• Serial number stickers: Located on the underside of the carrier board or on the packaging box
• MAC addresses: Software-assigned and managed by the OS. Check with:

  ip link show
  

  or

  cat /sys/class/net/wan/address
  

Networking

Can I bond the 4 Ethernet ports for more speed?

No. All 4 ports share the single 1Gbps connection from the CM4. The Realtek RTL8367RB is a switch, not an aggregator.

The only benefit of bonding would be redundancy (failover if one port fails), not increased throughput.

What are the Ethernet port speeds?

Board Versions

What’s the difference between v1.5 and v2.0?

Note: If upgrading from v1.5 to v2.0, your front panel wiring may need adjustment due to the J2 header location change.

Logging

Why are there no logs from before a reboot?

Raspberry Pi OS keeps the systemd journal in RAM only (Storage=volatile), so every reboot discards all logs. This is a Raspberry Pi OS default rather than an Exaviz setting.

It matters because rebooting a misbehaving board destroys the evidence of why it misbehaved. We recommend enabling persistent logging, particularly on any board you are actively diagnosing.

Note that setting Storage=persistent in /etc/systemd/journald.conf does not work. The Raspberry Pi drop-in takes precedence and your setting is silently ignored.

See No logs from before a reboot for how to enable it, how to verify it worked, and the write-wear trade-off to weigh first.

More Questions?

Contact us at support@exaviz.com with your question. We’ll respond and may add common questions to this FAQ.

Next Steps

• Troubleshooting - Detailed solutions
• Hardware Interface - Connector reference
• Software - OS configuration and drivers
• Getting Started - Setup guide

Last modified October 12, 2026