TOP1 Raspberry Pi Compute Module 4 Basic Expansion Board - Compact CM4

Our review of the TOP1 Raspberry Pi Compute Module 4 Basic Expansion Board finds it is best suited to makers and developers who need a compact, fully featured carrier board for the Raspberry Pi Compute Module 4. The biggest reason to buy is that it packs a wide set of connectors and a Standard CM4 socket into a credit-card sized board, making it easy to evaluate CM4 variants or integrate networking and storage into prototypes with minimal extra hardware.

Key Features

• CM4 socket: Supports all Compute Module 4 variants so developers can swap between Lite and eMMC versions without changing the base board.
• Networking: Built-in Gigabit Ethernet RJ45 lets networked projects connect at full wired speeds without an external adapter.
• Storage options: MicroSD slot for CM4 Lite and an M.2 M key slot that accepts communication modules or NVMe storage for flexible storage and expansion.
• Peripheral connectivity: Dual HDMI (one via FFC), multiple USB 2.0 ports and color-coded 40PIN GPIO make hooking up displays, cameras and accessories straightforward.
• Power and cooling: USB Type-C 5V/2.5A input and a fan header with speed control help keep a loaded CM4 cooled and reliably powered.

Who It's For

This board is ideal for engineers, hobbyists, and systems integrators who want a compact development or evaluation platform for the Raspberry Pi Compute Module 4 with ready access to networking, display and storage interfaces. Its credit-card size and standard GPIO header also make it handy for small embedded projects and proofs of concept.

Users who need industrial I/O with isolation, built-in wireless antennas, or PCIe lanes exposed as full-size slots should look elsewhere, since this board focuses on convenience and compactness rather than heavy industrial connectivity.

Pros & Cons

Pros

• Wide connector set including dual HDMI, dual CSI camera ports and dual DSI display support enables multimedia projects.
• Integrated Gigabit Ethernet and M.2 slot provide strong networking and optional NVMe or communication module expansion.
• Compact footprint with standard 40PIN GPIO makes it easy to transplant existing Raspberry Pi HATs and accessories.
• Onboard RTC and fan header add practical features for always-on or thermally sensitive builds.

Cons

• Only USB 2.0 ports are available, so high-speed USB 3.0 peripherals will be limited by interface speed.
• The board requires careful handling: do not plug or unplug anything other than USB and HDMI while powered.

Specifications

Product	Mini Base Board for Raspberry Pi Compute Module 4
CM4 Socket	Standard CM4 socket, supports Lite and eMMC variants
Networking	Gigabit Ethernet RJ45
Storage	MicroSD slot (for CM4 Lite), M.2 M key slot
Display & Camera	2x HDMI (one via FFC), 2x MIPI CSI-2, MIPI DSI port
USB	2x USB 2.0 Type-A, 2x USB 2.0 via FFC
Power	USB Type-C 5V / 2.5A input; fan header and RTC battery socket
Dimensions	85 x 56 mm

Our Verdict

The TOP1 CM4 Basic Expansion Board is a compact, capable carrier that offers excellent value for anyone prototyping or deploying a Raspberry Pi Compute Module 4 with networked or multimedia needs. Its broad set of connectors, M.2 option and onboard RTC and fan header make it a practical choice for embedded projects; those needing USB 3.0 or heavy industrial I/O should consider alternate boards.

Frequently Asked Questions

Does this board work with all CM4 variants?
Yes, the standard CM4 socket supports Compute Module 4 Lite and eMMC series modules.

Can I use an NVMe SSD in the M.2 slot?
The M.2 M key supports communication modules or NVMe SSDs, subject to the CM4 carrier and module capabilities.

What power input is required?
Use the USB Type-C 5V / 2.5A input and avoid plugging or unplugging devices other than USB and HDMI while the board is powered.