The Raspberry Pi series of single-board computers have long been the darling of Home Assistant enthusiasts, retro console creators, and robotics builders. It's remained the go-to platform for Home Assistant beginners, despite there being more powerful alternatives like the Orange Pi 5 Plus or the Odroid N2+. These alternatives simply can't compete in terms of support and user base. But today, the game changes as the Raspberry Pi Foundation announces the newest member of the Pi family: the Raspberry Pi 5. Let's delve into what's new and why you might want to retire your trusty Raspberry Pi 4 or 3 in favour of this shiny new toy.
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Under the Bonnet: Hardware additions
While it's worth briefly noting that the Raspberry Pi 5 is the first Pi to feature silicon designed in-house in Cambridge, there are some even more exciting updates for those planning to run Home Assistant OS on it.
Introducing an on-board PCI Express interface
For those fretting over the lifespan of their microSD cards, the Raspberry Pi 5 offers a perfect solution: a PCI Express (PCIe) 2.0 x1 interface. While it might not harness the power of the graphics card in your gaming rig, it does facilitate an effortless connection to SSDs. This interface can handle transfer speeds of up to 500 MB/s, and in early 2024, the Raspberry Pi Foundation plans to introduce two Hardware Attached on Top (HAT) options that will make use of it.
The first HAT adheres to the familiar form factor, covering most of the Raspberry Pi 5, except for the USB and Ethernet ports. This HAT enables you to connect larger devices like SSDs and other peripherals, such as Google's Coral accelerators. With this HAT installed, you will need to leave the top case off, likely exposing the electronics to the environment.
The second, smaller, HAT supports 2230- and 2243-format devices. Its reduced footprint means it will comfortably fit within the official case. Speaking of the case, it now also includes a small fan with fluid dynamic bearings, capable of cooling the Raspberry Pi 5 and any connected peripheral, based on temperature. By removing the top case, you can stack multiple cases and even mount HATs on top of the fan.
PoE+ HAT: A significant upgrade
Although the Raspberry Pi 5 doesn't incorporate PoE+ (Power over Ethernet) directly, a new HAT designed for this function is slated for launch in early 2024. Mirroring the compact M.2 HAT, the PoE+ HAT fits snugly inside the official case without obstructing the GPIO or hindering the airflow generated by the fan. Capable of supplying the Raspberry Pi 5 with a robust 25W, it leaves ample headroom even for high-load processes. In comparison, the new Pi consumes around 12W during such processes, a noticeable increase from the 8W consumed by the Raspberry Pi 4.
Decoding the Raspberry Pi 5: A closer look at its chips
The Raspberry Pi 5 has been four years in the making, and as such, tech enthusiasts are rightfully eager to see the improvements in performance. The star player in this tech upgrade is the new Broadcom application processor, the BCM2712, that forms the heart of the Pi 5.
Enter The quad-core Cortex-A76 processor
The BCM2712 application processor by Broadcom is the powerhouse behind the Raspberry Pi 5. Created through a 16-nanometer manufacturing process, it is approximately 60% smaller than the preceding BCM2711 AP that powered the Raspberry Pi 4. The new processor replaces the slightly greying-around-the-edges ARM Cortex-A72 CPU with a fresher ARM Cortex-A76 CPU. This processor also graced the Snapdragon 855 SoC that powered the likes of the Samsung Galaxy S10 and OnePlus 7 series. Despite being launched in 2018, the ARM Cortex-A76 still packs a punch and plays a key role in keeping the Raspberry Pi affordable.
With a new CPU comes increased clock speeds, and the smaller size means less heat generation – a win-win! The Broadcom BCM2712 clocks in at a zippy 2.4 GHz, a significant upgrade from the 1.8 GHz max of the Raspberry Pi 4. But the benefits don't stop there. The new processor also offers more instructions per clock (IPC) and lower energy per instruction, making it a lean, mean, computing machine.
Broadcom VideoCore VII: A graphic upgrade
The BCM2712 isn't just a one-trick pony, as it also boasts a vastly improved GPU, Broadcom’s VideoCore VII. The Raspberry Pi 5 can handle two 4K/60 FPS HDMI displays, a step up from the dual 4K/30 FPS displays the Raspberry Pi 4 could manage. The codec department also sees an upgrade with a new 4K/60 FPS HEVC decoder. However, it seems the elusive hardware-based AV1 decoding remains just out of reach.
Raspberry Pi 5: A performance powerhouse
So, how does all this newfangled tech translate into real-world performance? The answer is quite astounding. According to the Raspberry Pi Foundation, the Pi 5 promises two to three times the CPU and GPU performance of its predecessor, the Raspberry Pi 4. So, it appears that the long wait for the Raspberry Pi 5 has indeed been worth it. This pint-sized powerhouse is set to make a big impact in the world of single-board computers.
Chiplets: The Raspberry Pi's future
The Raspberry Pi has always been a crowd favourite, but until the fourth generation, it was plagued by a critical flaw: sluggish I/O speed. This caused a disappointing performance in not only USB but also network speeds. The Raspberry Pi 4 made commendable strides by separating the USB and Ethernet bus. But the real game-changer is the Raspberry Pi 5.
Raspberry Pi 5: Out with bottlenecks, in with chiplets
The Raspberry Pi 5 introduces the RP1, a bespoke chiplet specifically designed for I/O functions. The RP1 has been in the making since 2016 by the same tech whizzes who developed the much-loved RP2040 microcontroller, and it finally gets its moment in the spotlight with the Raspberry Pi 5.
The RP1-CO I/O controller is no slouch, boasting two USB 3.0 and two USB 2.0 interfaces, a Gigabit Ethernet controller, two four-lane MIPI (Mobile Industry Processor Interface) transceivers for camera and display, 3.3V GPIO, and an array of GPIO-multiplexed low-speed interfaces (UART, SPI, I²C, I²S, and PWM). It connects to the application processor via a high-speed 16 Gb/s four-lane PCI Express 2.0 interface.
Interfaces requiring higher speeds, such as SDRAM, HDMI, and PCI Express, remain directly linked to the application processor. This chiplet architecture cleverly distributes the workload, ensuring stable speeds on all I/O interfaces and freeing up resources on the AP.
Power management gets a chiplet upgrade too
The other notable chip in the Raspberry Pi 5 is the Renesas DA9091. This chiplet integrates eight separate switch-mode power supplies to generate the various voltages required by the board. This mighty little power manager not only pumps a whopping 20 amps of current to the BCM2712, but it also introduces two much-anticipated features to the Raspberry Pi 5.
For the first time, Raspberry Pi users can enjoy an on-board power button with support for hard and soft power-off and power-on events. No more unplugging power supplies to boot your Raspberry Pi. It's a wonder it took this long to add such a seemingly simple feature, but better late than never, eh?
The second new feature is support for a real-time clock (RTC). This can be powered by an external supercapacitor or a rechargeable lithium-manganese cell, sold separately. So now your Raspberry Pi will keep ticking along with the times, even when powered down.
In conclusion, the Raspberry Pi 5's introduction of chiplets for specific functions like I/O and power management is a massive leap forward, promising a performance that is smooth, efficient and most importantly, speedy. With this, the Raspberry Pi 5 is not just a mini-computer; it's a mini marvel.
