For small partners that are often mixed in the open source hardware, I believe that some single board computers on the market are unfamiliar, what Raspberry, Banana, BeagleBone Black, UP Board, etc. These most are ARM CoretX-A A series of application processors or higher is some of the X86 series processors, regardless of performance or functionality, basically meet the needs of the present partners. But don't you think less? The whole world around the ARM is so single, have we not better or more choice? have! Hifive unleashed, this is the world's first RISC-V, support Linux system, unique single board computer, can be called the ultimate form of RISC-V.
HiFive Unleashed, an open source, ultra-open source
Many people have never heard of RISC-V, even if they heard, it is only a structure that is relatively low, and may only be used as a low-power microcontroller series for IooT application classes. No, this article's hiFive unleashed can be said to be raised for RISC-V.
Hifive Unleash is a 64-bit development platform for RISC-V support Linux on-chip systems. The core of the board is SiFive Fu540 (Freedom U540) SOC, 4 + 1 multi-core configuration, the main frequency up to 1.5GHz, DDR4 (ECC) onboard 8GB.
The resource distribution of the Hifive Unleashed onboard is as follows:
The hardware system framework of the board can refer to the figure below.
Onboard main resources:
SIFIVE FREEDOM U540 SOC
8 GB DDR4 with ECC
Gigabit Ethernet port
Issi 32MB 4 SPI Flash
MicroSD card, for storage system
FMC connector for peripheral expansion
To be honest, it may be that all kinds of boards are more comfortable, but it is very stunning, but I feel that the deepest is 3 points: First, the world can run GNU / Linux to handle RISC-V treatment Hardware; Second, the development board actually carries 8GB of DDR4 (with ECC) memory, which is basically there is no right in the development board; third is the 64-bit RISC-V SOC onboard.
So let's take a look at this legendary SOC.
Freedom U540 SOC
It can be seen that the Freedom U540 SOC and the ARM series application processor have no difference in peripherals, and the main difference is that the integrated 4 + 1 processing core. From the versions, Freedom U540 SOC is manufactured with TSM 28 nm HPC process. The SOC integrates a 4 U54 RV64GC kernel for 1.5GHz and a E51 RV64IMAC management kernel that supports SV39 virtual memory. Then what differences they have? What is the performance?
E51 RISC-V core, including instruction memory system, instruction acquisition unit, execution line, data memory system, and support for global, software, and timer interrupts. E51 Nuclear Support Machine and USER Permission Mode and Standard Multiply, Atomic, and Compressed RISC-V Instruction Sets (RV64imac), which features the following table.
E51 core characteristics
The U54 RISC-V kernel, including instruction memory systems, instruction acquisition unit, execution line, floating point unit, data memory system, memory management unit, and support global, software, and timer interrupts. The 4 U54 cores, each of the cores have an efficient level 5 ordered flow line that supports 32KB L1 instructions and data caches, and all kernels share a 2MB L2 cache. Real-time functions can be combined with high-speed SRAM by using L1 instructions and L2 caches to ensure real-time functions. U54 kernel supports Machine, Supervisor, and USER permission models and standard multiplication, single-precision floating point, double precision floating point, Atomic and Compressedrisc-V extensions (RV64IMAFDC). See below.
U54 core characteristics
The difference between the two, the E51 core supports SV39 virtual memory and biases low power, the function execution of the control class (a bit like microcontroller), and the U54 supports floating point units, supports ECC function, with stronger performance, more biary For AI, machine learning, network, gateway, and smart Internet access (a bit like application processor). The combination of the two is more like a BIG.LITTLE structure in ARM, or a bit like application processor and association meaning.
Software & Development Environment
In addition to the use of Linux, Hifive Unleashed software will also be equipped with a rich SDK, there will be software DEMOs and easy-to-install binary tools.
In addition, it is learned from the official website that RISC-V has an integrated developer environment that is an integrated developer environment that can be used to write and debug software for SIFIVE-based processors. Freedom Studio is bundled with the pre-built RISC-V GCC tool chain based on the industry standard Eclipse platform. It is bundled with the OpenOCD, sample programs and documents. However, it seems that it only supports RISC-V-based microcontroller series products.
It's time to build a world's first RISC-V, support Linux computer - Hifive Unleashed expansion board
More unfortunately, although Hifive Unleashed looks strong, it is not equipped with GPUs and other coordinator, but what is the things forever. MicroSemi's programmable solution department provides an expansion board for HiFive Unleashed, connected to the FMC interface, you only need to add the Linux system by adding HDD, SSD, audio card, network adapter, and / or graphics card on the expansion board. Transplant to this platform with the package you want.
The entire expansion plate is mostly much more than the Hifive Unleashed board, with a length of 10.7 inches, 4.62 inches and needs to match a separate power supply. The expansion board is pre-programmed with a bridge chip based on the PCIE interface. It can easily implement the PCIe extension, the main functions of the onboard are as follows:
300K logic unit, low power POLARFIRE FPGA
24 channel PCIE switching switch
X1 PCI Express card connector
X16 PCI Express card connector, four PCIe Gen2 channels
SSD M.2 connector
SATA connector
HDMI connector
EMMC NAND FLASH
USD card slot
USB-UART
4 gbit ddr4 x16
SPI Flash is used for remote FPGA updates, QSPI Flash is connected to GPIO
Two CAN transceivers
FMC connected to HFU540-4A00 Suite
Hifive Unleashed is connected to the expansion board, you can see that the "core board" only accounts for 1/3 of the expansion board.
Be
With the combination of Hifive Unleashed and expanded boards, add some mouse, keyboard, graphics card, HDD / SSD or PCIe USB card, etc., you can easily build a unique PC based on RISC-V, support Linux system, or It is used for Linux development workstations.
summary
Free, open is the essence of RISC-V, and Hifive Unleashed is based on open source attributes, which is designed to encourage third-party access. Users can access the peripheral IP access to open source code through the TileLink interface, with the HiFive Unleashed expansion board plus already Mature part of the peripheral function, users can easily build the world's first RISC-V, support Linux PC, even workstations. This is the strength of the HiFive Unleashed HiFive Unleashed, which is sourced, perhaps, may also be the ultimate form that the RISC-V can achieve now.
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