The Raspberry Pi Compute Module 4 Review - SB Components

It’s become a tradition that we follow each Raspberry Pi model with a system-on-module variant based on the same core silicon. Raspberry Pi 1 gave rise to the original Compute Module in 2014; Raspberry Pi 3 and 3+ were followed by Compute Module 3 and 3+ in 2017 and 2019 respectively. Only Raspberry Pi 2, our shortest-lived flagship product at just thirteen months, escaped the Compute Module treatment.

It’s been sixteen months since we unleashed Raspberry Pi 4 on the world, and today we’re announcing the launch of Compute Module 4, starting from $25.

Over half of the seven million Raspberry Pi units we sell each year go into industrial and commercial applications, from digital signage to thin clients to process automation. Many of these applications use the familiar single-board Raspberry Pi, but for users who want a more compact or custom form factor, or on-board eMMC storage, Compute Module products provide a simple way to move from a Raspberry Pi-based prototype to volume production.

A step change in performance

Built on the same 64-bit quad-core BCM2711 application processor as Raspberry Pi 4, our Compute Module 4 delivers a step change in performance over its predecessors: faster CPU cores, better multimedia, more interfacing capabilities, and, for the first time, a choice of RAM densities and a wireless connectivity option.

Raspberry Pi Compute Module 4

You can find detailed specs here, but let’s run through the highlights:

• 1.5GHz quad-core 64-bit ARM Cortex-A72 CPU
• VideoCore VI graphics, supporting OpenGL ES 3.x
• 4Kp60 hardware decode of H.265 (HEVC) video
• 1080p60 hardware decode, and 1080p30 hardware encode of H.264 (AVC) video
• Dual HDMI interfaces, at resolutions up to 4K
• Single-lane PCI Express 2.0 interface
• Dual MIPI DSI display, and dual MIPI CSI-2 camera interfaces
• 1GB, 2GB, 4GB or 8GB LPDDR4-3200 SDRAM
• Optional 8GB, 16GB or 32GB eMMC Flash storage
• Optional 2.4GHz and 5GHz IEEE 802.11b/g/n/ac wireless LAN and Bluetooth 5.0
• Gigabit Ethernet PHY with IEEE 1588 support
• 28 GPIO pins, with up to 6 × UART, 6 × I2C and 5 × SPI

New, more compact form factor

Compute Module 4 introduces a brand new form factor, and a compatibility break with earlier Compute Modules. Where previous modules adopted the JEDEC DDR2 SODIMM mechanical standard, with I/O signals on an edge connector, we now bring I/O signals to two high-density perpendicular connectors (one for power and low-speed interfaces, and one for high-speed interfaces).

This significantly reduces the overall footprint of the module on its carrier board, letting you achieve smaller form factors for your products.

32 variants

With four RAM options, four Flash options, and optional wireless connectivity, we have a total of 32 variants, with prices ranging from $25 (for the 1GB RAM, Lite, no wireless variant) to $90 (for the 8GB RAM, 32GB Flash, wireless variant).

We’re very pleased that the four variants with 1GB RAM and no wireless keep the same price points ($25, $30, $35, and $40) as their Compute Module 3+ equivalents: once again, we’ve managed to pack a lot more performance into the platform without increasing the price.

You can find the full price list in the Compute Module 4 product brief.

Compute Module 4 IO Board

To help you get started with Compute Module 4, we are also launching an updated IO Board. Like the IO boards for earlier Compute Module products, this breaks out all the interfaces from the Compute Module to standard connectors, providing a ready-made development platform and a starting point for your own designs.

The IO board provides:

• Two full-size HDMI ports
• Gigabit Ethernet jack
• Two USB 2.0 ports
• MicroSD card socket (only for use with Lite, no-eMMC Compute Module 4 variants)
• PCI Express Gen 2 x1 socket
• HAT footprint with 40-pin GPIO connector and PoE header
• 12V input via barrel jack (supports up to 26V if PCIe unused)
• Camera and display FPC connectors
• Real-time clock with battery backup

CAD for the IO board is available in KiCad format. You may recall that a few years ago we made a donation to support improvements to KiCad’s differential pair routing and track length control features; now you can use this feature-rich, open-source PCB layout package to design your own Compute Module carrier board.

In addition to serving as a development platform and reference design, we expect the IO board to be a finished product in its own right: if you require a Raspberry Pi that supports a wider range of input voltages, has all its major connectors in a single plane, or allows you to attach your own PCI Express devices, then Compute Module 4 with the IO Board does what you need.

We’ve set the price of the bare IO board at just $35, so a complete package including a Compute Module starts from $60.

Compute Module 4 Antenna Kit

We expect that most users of wireless Compute Module variants will be happy with the on-board PCB antenna. However, in some circumstances – for example, where the product is in a metal case, or where it is not possible to provide the necessary ground plane cut-out under the module – an external antenna will be required. The Compute Module 4 Antenna Kit comprises a whip antenna, with a bulkhead screw fixture and U.FL connector to attach to the socket on the module.

When using ether the Antenna Kit or the on-board antenna, you can take advantage of our modular certification to reduce the conformance testing costs for your finished product. And remember, the Raspberry Pi Integrator Programme is there to help you get your Compute Module-based product to market.

Our most powerful Compute Module

This is our best Compute Module yet. It’s also our first product designed by Dominic Plunkett, who joined us almost exactly a year ago.

I sat down with Dominic last week to discuss Compute Module 4 in greater detail, and you can find the video of our conversation here. Dominic will also be sharing more technical detail in the blog tomorrow.

In the meantime, check out the Compute Module 4 page for the datasheet and other details, and start thinking about what you’ll build with Compute Module 4.