Raspberry Pi 4 is now on sale, starting at $35. This is a comprehensive upgrade, touching almost every element of the platform. Raspberry Pi 4 provides a PC-like level of performance for most users, while retaining the interfacing capabilities and hackability of the classic Raspberry Pi line.
This is the first time Raspberry Pi offers a choice in memory size, including 1 GB RAM for $35, 2 GB RAM for $45 and 4 GB RAM for $55. And this latest Raspberry Pi has been designed to be compatible with existing HATs and other accessories.
Raspberry Pi 4 has moved from USB micro-B to USB-C for a power connector. This supports an extra 500 mA of current, ensuring users have a full 1.2 A for downstream USB devices, even under heavy CPU load.
To accommodate dual display output within the existing board footprint, the type-A (full-size) HDMI connector has been replaced with a pair of type-D (micro) HDMI connectors.
The Gigabit Ethernet MagJack has moved to the top right of the board, from the bottom right, greatly simplifying PCB routing. The 4-pin Power-over-Ethernet (PoE) connector remains in the same location, so Raspberry Pi 4 remains compatible with the PoE HAT.
The Ethernet controller on the main SoC is connected to an external Broadcom PHY over a dedicated RGMII link, providing full throughput. USB is provided via an external VLI controller, connected over a single PCI Express Gen 2 lane, and providing a total of 4 Gbps of bandwidth, shared between the four ports.
All three connectors on the right-hand side of the board overhang the edge by an additional millimeter, with the aim of simplifying case design. In all other respects, the connector and mounting hole layout remains the same, ensuring compatibility with existing HATs and other accessories.
Raspberry Pi 4 is shipping a radically overhauled operating system, based on the forthcoming Debian 10 Buster release. This brings numerous behind-the-scenes technical improvements, along with an extensively modernized user interface, and updated applications including the Chromium 74 web browser.
One notable step forward is that for Raspberry Pi 4, the legacy graphics driver stack used on previous models is being retired. Instead, Raspberry Pi 4 uses the Mesa “V3D” driver developed by Eric Anholt at Broadcom over the last five years. This offers many benefits, including OpenGL-accelerated web browsing and desktop composition, and the ability to run 3D applications in a window under X. It also eliminates roughly half of the lines of closed-source code in the platform.
According to the developers of Raspberry Pi 4, good, low-cost USB-C power supplies (and USB-C cables) are surprisingly hard to find. So they worked with Ktec to develop a suitable 5 V/3 A power supply; this is priced at $8, and is available in UK (type G), European (type C), North American (type A) and Australian (type I) plug formats.
If you’d like to re-use a Raspberry Pi 3 Official Power Supply, resellers are offering a $1 adapter which converts from USB micro-B to USB-C. The thick wires and good load-step response of the old official supply make this a surprisingly competitive solution if you don’t need a full 3 amps.
At the end of last year, Raspberry Pi Press released the Official Raspberry Pi Beginner’s Guide. Gareth Halfacree has produced an updated version, covering the new features of Raspberry Pi 4 and the updated operating system.
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