What highlights are worth paying attention to

As soon as the Raspberry Pi 5 was announced, it sparked widespread discussion among engineers. (Original post address: The Raspberry Pi 5 has been released, and the changes are significant http://bbs.eeworld.com.cn/thread-1258069-1-1.html)

First, let’s talk about the most concerning aspect: the price, which comes in two versions:

• 4GB RAM version: $60;

• 8GB RAM version: $80.

Changes/highlights in a nutshell:

• SoC: BCM2712 Cortex-A76x4 @2.4GHz, 16nm process, offering a 2-3 times performance improvement over Raspberry Pi 4;

• Dual 4kp60 HDMI outputs;

• Faster SD interface supporting SDR104 mode (UHS-I), foreign media reported speeds of 90MB+;

• Newly added RP1 “southbridge” chip designed by the PICO team (located behind the USB interface), used to bridge PCIe, USB, GPIO, LAN, CSI/DSI interfaces, allowing 2xUSB3.0 to support 5Gbps rates simultaneously;

• PCIe 2.0×1 interface (FPC socket form), supports M.2 SSD (requires HAT adapter);

• 4-pin fan interface, supports PWM speed regulation and speed feedback for active cooling (the official active cooling kit looks great and is reasonably priced at $5);

• Newly added Renesas DA9109 PMIC (behind the Type-C interface), providing power measurement functionality and USB-PD power support;

• RTC and RTC battery power supply;

• Supports Power over Ethernet (PoE), but you need to purchase a new PoE HAT to use it;

• Independent 3-pin URAT interface for easy debugging;

• Power button! (Extremely advanced);

• 40-pin GPIO uses SMD soldering;

• Removed 3.5mm headphone and analog video interfaces, analog video changed to a 2-pin pin, audio output needs to go through HDMI/USB;

• Supports multiple cameras, and in terms of encoding, both libcamera and Picamera2 Python modules support multiple cameras;

• The appearance is similar to the previous generation, but some new elements have been updated for the new chip set;

• The Raspberry Pi operating system will be released in mid-October.

In summary:

• The Raspberry Pi 5 has made many improvements, adding the long-awaited PCIe interface (although it’s only 2.0, SSD still requires HAT adapter);

• The CPU performance has greatly improved, but in today’s world where Arm/Raspberry Pi variants are blooming, it is not considered too strong.

The Raspberry Pi 5 has three new chips, detailed analysis as follows:

BCM2712

BCM2712 is Broadcom’s new 16nm application processor (AP), succeeding the 28nm BCM2711 AP of the Raspberry Pi 4.

BCM2712 features a quad-core 64-bit Arm Cortex-A76 processor, clocked at 2.4GHz, with 512KB L2 cache per core and 2MB shared L3 cache. Cortex-A76 is the third generation microarchitecture after Cortex-A72, providing more instructions per clock (IPC) and lower energy per instruction. The combination of newer cores, higher clock speeds, and smaller process geometries results in a faster Raspberry Pi.

BCM2712’s GPU is also stronger. Broadcom’s VideoCore VII, developed in Cambridge, has updated hardware video scalers (HVS) capable of driving two 4Kp60 HDMI displays simultaneously, compared to the single 4Kp60 or dual 4Kp30 on the Raspberry Pi 4. The Kp60 HEVC decoder and new image sensor pipeline (ISP) have all been improved, enhancing the multimedia subsystem. To maintain memory bandwidth, the Raspberry Pi 5 has a 32-bit LPDDR4X SDRAM subsystem with a transfer rate of 4267MT/s, compared to 2000MT/s on the Raspberry Pi.

RP1

RP1 is the I/O controller of Raspberry Pi 5, designed by the same team that provided the RP2040 microcontroller, implemented on TSMC’s mature 40LP process. It has two USB 3.0 and two USB 2.0 interfaces; a Gigabit Ethernet controller; two four-channel MIPI transceivers for cameras and displays; analog video output; 3.3V general-purpose I/O (GPIO); and the usual GPIO multiplexed low-speed interfaces (UART, SPI, I2C, I2S, and PWM). The four-channel PCI Express 2.0 interface provides a 16Gb/s link back to BCM2712.

RP1 has been in development since 2016 and is the longest-running, most complex, and most expensive ($15 million) project undertaken by Raspberry Pi. Over the years, it has undergone significant evolution as demands have changed: the C0 step used on Raspberry Pi is the third major revision of the chip. Although its interfaces differ in detail from the BCM2711’s, functionally, they are designed to be very similar, ensuring high compatibility with earlier Raspberry Pi devices.

Previous Raspberry Pi models were built on an integrated AP architecture: while some peripheral functions were provided by external devices (such as the Via Labs VL805 USB controller and hub on Raspberry Pi 4), almost all I/O functions were integrated into the AP itself. Raspberry Pi realized early on that as APs migrated to increasingly newer process nodes, this approach would ultimately become unsustainable both technically and economically.

Thus, Raspberry Pi 5 is now built on a chiplet architecture. Here, the AP only provides the main fast digital functions, the SD card interface (due to circuit board layout reasons), and the fastest interfaces (SDRAM, HDMI, and PCI Express). All other I/O functions are offloaded to a separate I/O controller, implemented on older, cheaper process nodes, and connected to the AP via PCI Express.

DA9091

In terms of power management, the Raspberry Pi 5 is equipped with the Renesas DA9091 “Gilmour” power management IC (PMIC), which integrates eight independent switch-mode power supplies to generate various voltages required by the circuit board, including four-phase core power capable of delivering 20A of current to power the Cortex-A76 cores and other digital logic chips in the BCM2712.

Like the BCM2712, DA9091 is the result of years of collaborative development efforts with Renesas’ team in Edinburgh, including two important features: one is a real-time clock (RTC) powered by an external supercapacitor or rechargeable lithium-manganese battery; the other is a PC-style power button, supporting hard and soft power off and booting.

The entire chip set retains two elements from Raspberry Pi 4: one is the Infineon CYW43455 combo chip providing dual-band 802.11ac Wi-Fi and Bluetooth 5.0 with low-power Bluetooth (BLE); although the chip itself remains unchanged, it is equipped with dedicated power supply rails to reduce power consumption and connects to the BCM2712 via an upgraded SDIO interface that supports DDR50 mode for higher potential throughput; the other is the Broadcom BCM54213 Gigabit Ethernet PHY providing Ethernet connectivity, which is the first time Raspberry Pi has attempted to solder it at a 45-degree angle on the board, a long-awaited feature for orthogonal layout enthusiasts and the company’s CTO.

In terms of accessories, the layout changes and performance/power consumption changes of the Raspberry Pi 5 require new accessories:

• $10 Raspberry Pi 5 case: integrated 2.79 (maximum) CFM fan, shaped like Raspberry Pi 4, includes features like inserting the SD card into the Raspberry Pi 5 development board without removing it, using spacers and GPIO header extenders to mount HATs on top of the fan;

• $5 active cooler: exclusively for overclocking players;

• $12 27W USB-C power supply: because it has changed from 5V/3A to 5V/5A, when using the standard 5V/3A (15W) USB-C power adapter, it will default to limiting downstream USB current to 600mA to ensure enough overhead to support workloads, which is lower than the 1.2A limit on Raspberry Pi 4. This power supply supports 5V/5A (25W) operating mode, and if the Raspberry Pi 5 firmware detects this product, it will increase the USB current limit to 1.6A, providing an additional 5W of power for downstream USB devices as well as an additional 5W onboard power budget. It seems that this has already reached the power consumption level of a lightweight laptop. It is worth noting that users can choose to override the current limit, specifying a higher value even when using a 3A adapter;

• Cameras and cables: to support existing camera and display users, Raspberry Pi provides FPC camera and display cables available in three lengths: 200mm ($1), 300mm ($2), and 500mm ($3);

• PoE+ HAT: in early 2024, Raspberry Pi will provide a new PoE+ HAT, integrating a planar transformer in the new layout and utilizing an optimized flyback converter architecture to maintain high efficiency across the entire 0-25W output power range;

• M.2 HAT: one of the most exciting new features of Raspberry Pi is the single-channel PCI Express 2.0 interface, and in early 2024, Raspberry Pi will provide a pair of mechanical adapter boards to convert between this connector and M.2 standard accessories, allowing users to connect NVMe SSDs and other M.2 format accessories;

• RTC battery: Raspberry Pi has procured Panasonic lithium-manganese rechargeable coin batteries, with pre-installed two-pin JST plugs and adhesive mounting pads. Priced at $5, it is suitable for powering the Raspberry Pi 5 real-time clock (RTC) when the main power is disconnected.

Comparing Raspberry Pi 4, the upgrades of Raspberry Pi 5 are significant. In summary, the performance has improved, video playback has become smoother, and storage bandwidth has increased. Furthermore, the RTC and power button are also “epic” updates.

For the current product line, Tom’s Hardware suggests: if you don’t want to buy the power supply and active cooler, just buy Raspberry Pi 4, which, despite being 4 years old, still offers rock-solid performance; if you only need GPIO without Linux, buy the $8 Raspberry Pi Pico W, which has proven to be a versatile and excellent MCU; if you want the best single-board computer, then Raspberry Pi 5 is the best choice.

Summary of Raspberry Pi models released to date, compiled by Electronic Engineering World

However, many people also express that Raspberry Pi has deviated from its original intention of being “a computer that everyone can afford”. So, how do engineers view this new product?

Responses are pessimistic, but there are still loyal fans

On the EEWorld forum, many engineers are loyal fans of Raspberry Pi. In their view, the practical upgrades of Raspberry Pi 5 are substantial, and it is an upgrade that engineers have been waiting for a long time. For example, the separation of the I/O bridge, the AP interface being PCIe-enabled, RTC, and PWM fan upgrades are all epoch-making for Raspberry Pi. Especially the self-developed southbridge, possibly in preparation for SoC changes, or even self-developed SoCs. The overall form of Raspberry Pi 5 is also increasingly resembling a computer rather than the traditional development board, which may change future use cases and applications.

However, at the same time, engineers believe that this upgrade may be in pursuit of catching up with other SBC platforms, but the upgraded CPU and GPU performance may still be weaker than the RK3588. The removal of the video encoder and the 3.5mm headphone jack, along with GPIO, MIPI, and SDIO being placed on the self-developed southbridge, makes it difficult to determine future compatibility. Compared to other mainstream platforms, the highlights remain lackluster.

From Phoronix’s benchmark tests, it can be seen that BCM2712 and RK3588 are neck and neck, but overall, the RK3588 wins more often (not excluding testing issues, more test data can be traced back from references). At the same time, the memory bandwidth of Raspberry Pi 5 has improved, but it is still not as good as most RK3588 development boards using dual-channel memory.

Some engineers have pointed out that the Raspberry Pi has long been a performance monster, with Raspberry Pi 4 being a power hog, making it hard to use without a fan. Earlier models like Raspberry Pi 2 and 3 could run for days on a larger power bank, but now it must be plugged into a power supply. Continuing to enhance performance will inevitably increase power consumption, which may further bind it to the cooling solutions.

This means that not only do you need to purchase a dedicated power supply, but also additional cooling solutions, which has already deviated from Raspberry Pi’s original intention of being “affordable”. On the other hand, Raspberry Pi 5 indeed requires 5V/5A PD power, while most PD adapters on the market are 5V/3A, and the lower gauge wires make it difficult to run full 5A. There is confusion about why, under the circumstances of using an independent PMIC chip, it doesn’t negotiate widely supported specifications or why there are no DC ports or onboard buck converters.

Tests from Tom’s Hardware have also shown that Raspberry Pi 5 indeed runs hotter. From hardware parameters, Raspberry Pi 5 overall increases by 1W, and under stress testing, the temperature reached 86.7°C, compared to 79.8°C for Raspberry Pi 4 under stress testing, indicating a higher temperature. However, using the official active cooler, the temperature of Raspberry Pi 5 can be reduced to 59.3°C. During testing, many cheap coolers were either incompatible or ineffective, making it wise to use the official active cooler or wait for third-party custom cooling solutions. Additionally, if you want to overclock, you must install an active cooler, as small passive coolers simply cannot handle the heat.

Another forum user raised concerns about the zero, mainly wanting to use it to run the IPFS software built into Linux, to create a P2P download tool for those who are not familiar with these things. However, the price of Raspberry Pi 5 is quite high; if it’s just for running Linux, it would be better to use cheaper domestic boards or old mini computers. For mass production, there are also better-priced options like Allwinner H618 and Orange Pi Zero2.

On Zhihu, engineers’ reactions are generally pessimistic. Most people’s rhetoric is that Raspberry Pi can no longer produce new features, and that open-source Arm cannot compete with RISC-V, that the ecosystem and x86 cannot be compared with SBC, and that the price is becoming like a financial product, completely deviating from its original intention. There are too many alternatives to Raspberry Pi, such as x86 mini hosts, or mini hosts paired with a 32-bit MCU to realize GPIO, and community support for software, drivers, and firmware has become the reason to choose Raspberry Pi.

At the same time, most engineers state that the biggest bottleneck for Raspberry Pi is that there is not even an external eMMC module, and they still have to buy the officially slow SD cards to use it. While it can support M.2, the speed is still limited to PCIe 2.0.

However, compared to Raspberry Pi 4, the USB 3.0 and microSD card reader interface speeds of Raspberry Pi 5 have doubled.

In this regard, engineers summarized the current situation of Raspberry Pi:

• There are at least twice as many boards with higher performance, such as various domestic RK3588 options; (for complaints, see the engineer’s article “Complaining About Various Domestic Raspberry Pi Alternatives”)

• There are many cheaper boards with significantly lower performance, and some OS cannot run on them;

• Too much emphasis on British manufacturing, supply chain management issues may arise, with shortages and price increases being potential problems; (the official frequently claims designed in-house here in Cambridge, UK., developed here in Cambridge, manufactured in Wales)

• Rich software and community ecology, this is something that any product finds it hard to match; however, the semi-open-source model is becoming less attractive to makers, and traditional teaching fields are being encroached upon by Android-based boards.

Of course, although there are many complaints, there are also many loyal fans of Raspberry Pi engineers who hold a wait-and-see attitude and expectations for Raspberry Pi 5, proposing more hopes, including:

• M.2 slot;

• Faster USB interfaces, Type-C host;

• Larger memory (to support docker, virtualization, local AI, etc.).

It is important to emphasize that Raspberry Pi is not just a toy; it is also a powerful productivity tool and will play a role in the industry. (Refer to the historical article from Electronic Engineering World “Raspberry Pi Got into Trouble Again, the Underestimated Single-Board Wonder”) So far, approximately 55 million Raspberry Pi computers have been sold, with last year’s reported revenue of $188 million and an operating profit of $20 million.

Of course, although engineers are complaining about the lack of appeal of Raspberry Pi 5, with RK3588 above and x86 external GPIO below, how it will perform in practice, whether there will be many software compatibility problems, and whether it will continue to be underutilized all need to be tested once it is actually released.

Finally, it should be emphasized that for those who do not like to tinker, purchasing any SBC may end up being underutilized.