MIPS, once a formidable competitor to ARM in the microprocessor field, had its golden era. However, in the mobile domain, MIPS gradually fell behind, and its academic development style significantly lagged behind ARM’s commercial progress. How many people still remember MIPS today?
Just when it seemed that MIPS was about to fade into obscurity, Imagination Technologies from the UK acquired MIPS for $60 million, aiming to integrate it with its PowerVR line and revive its former glory. However, that was an old story from 2012.
Speaking of Imagination, one cannot forget PowerVR, which is Imagination’s pride and joy, having been the GPU of choice for Apple. Moreover, GPU technologies from Samsung and MediaTek also stem from PowerVR.
However, after acquiring MIPS, Imagination seemed to have little activity, only launching the Warrior series of microprocessors in 2013, covering various 32-bit and 64-bit configurations, which did not generate significant response, nor did they release corresponding evaluation development boards.
Out of nowhere, Imagination launched a product called Creator Ci20 last year, aimed at evaluating MIPS and PowerVR GPUs, seemingly preparing to enter the SBC market!
The Creator Ci20 single-board computer, launched by Imagination, not only uses its PowerVR SGX540 but also features a CPU SoC from Ingenic, the JZ4780 (based on the MIPS architecture). The development board integrates communication interfaces like WiFi/BT/ETH and other commonly used peripherals, hoping to provide a suitable evaluation and learning platform for MIPS enthusiasts. This development board was released around the same time as the RPI 2, allowing for a comparative analysis between the two boards, which will be the focus of this review. I have previously used the Loongson evaluation board developed by the Loongson Club and found it quite satisfactory, so I feel quite at home with the Ci20 development board and can’t wait to experience it.
Creator Ci20 Unboxing
The CPU SoC on the Creator Ci20 development board is the JZ4780, based on the MIPS architecture. The hardware configuration of the development board is not high, but the interfaces are quite comprehensive.
The packaging of the Ci20 lists some of the main features of the development board. The hardware features mainly include: MIPS architecture, PowerVR GPU, and FlowCloud support; the software platform supports mainstream Linux and Android systems. The development kit is sold in boxed form, with a price of around RMB 550 (including tax) on MOUSER.
The Ci20 package includes one Creator Ci20 development board, one USB power cable, a brief printed documentation, and a set of six hexagonal plastic support screws. The internal foam protects the development board from shocks.
The size of the Ci20 development board is approximately 90X95mm. The original Ci20 development board was printed in green ink, while the current version is V2, which uses purple ink. The printed document provides a quick guide URL to help users get started quickly. However, there is only an English page, with no Chinese documentation.
Hardware Introduction
The Creator Ci20 is primarily positioned against the Raspberry Pi 2B, with a CPU clock speed that is not high, using a MIPS32 architecture with dual cores, operating at a frequency of 1.2GHz. In fact, Imagination launched a 64-bit architecture CPU named Warrior back in 2013, targeting the mobile phone and tablet market. However, this CPU was not used in the Creator Ci20. Relatively speaking, the features of the Creator Ci20 are more reflected in the provided peripheral interfaces. In addition to integrating conventional audio and video interfaces on the development board, it also includes WiFi/BT/ETH communication interfaces and an infrared receiver!
The peripherals on the Creator Ci20 development board are mainly concentrated on the front. The total physical memory of 1GB is composed of four 256MB chip particles (with two memory chips on the back), and the 8GB EMMC chip and wireless/Bluetooth chip are located on the back of the development board.
JZ4780 Module
The JZ4780 SoC used on the Creator Ci20 is a microprocessor launched by Beijing Ingenic, based on the XBurst CPU core. Since early 2007, the JZ47xx series microprocessor chips have quickly found extensive applications in fields such as biometric recognition, educational electronics, multimedia players, e-books, and tablets, thanks to their excellent cost-performance ratio, strong multimedia processing capabilities, and ultra-low power consumption. The JZ47xx series has become the most widely shipped and applied self-innovated microprocessor product in China. This CPU can be seen in many fingerprint attendance machines.
This microprocessor has two 1.2GHz cores, each with a 64KB primary cache and a total of 512KB secondary cache. The CPU uses a 9-stage pipeline for processing tasks. The package form is BGA, and the chip size is 17X17mm. The SoC also integrates a PowerVR SGX540 GPU, which includes 3D and 2D acceleration functions, with performance roughly equivalent to the GPU used in the iPhone 4S.
JZ4780 is based on the MIPS architecture. Compared to microprocessors based on the ARM architecture, although both belong to the RISC instruction set system, their instruction sets are entirely different. This means that most codes compiled for ARM cannot run on this CPU. If you want to run related programs on the Ci20, you need to obtain the source code of the program and recompile it before execution.
Storage System
The Creator Ci20 development board integrates 1GB of DDR3 memory and 8GB of EMMC storage. 1GB of DDR3 memory is generally sufficient for typical embedded applications, and the memory chips used are Samsung’s K4B2G0846, with a single chip capacity of 2Gbit, and each chip has a capacity of 256MB, totaling 1GB of memory. This memory can achieve a maximum data transfer rate of 900Mb/s at a working frequency of 900MHz; specific performance tests will be detailed later.
The 8GB EMMC storage can be used directly to store the system firmware, saving the cost of purchasing an additional SD card. This is a widely used EMMC storage from Micron, with average performance but a low price; many USB drives use this storage chip model. The storage uses MLC storage units, with a width of 8 bits; in synchronous access mode, the performance can reach 200MT/s; in asynchronous access mode, the read/write speed can reach 50MT/s. Detailed read/write speed tests will be provided later.
In addition to these built-in storage devices, the Creator Ci20 development board also provides SD card and USB storage interfaces, making it easy to add external storage to the development board. The RPI series does not provide built-in EMMC storage support; programs must use an additional Micro SD card to provide external storage capabilities.
Communication Capabilities
Compared to the RPI 2, the Ci20’s main feature is its rich external network communication capabilities. The Ci20 development board provides not only a standard ETH network interface but also WiFi/BT connectivity.
The onboard wireless communication module is the RK903, which includes WiFi functionality, supporting the IEEE 802.1 b/g/n protocol, operating on the 2.4GHz frequency band; the FM function supports the 76MHz-108MHz frequency band; and the Bluetooth function has been upgraded from the initial version 2.1 to version 4.0. The antenna is located below the wireless module, and no independent SMA antenna interface is provided.
The Ethernet controller model is DM9000C, a 10/100M fast Ethernet controller launched by DAVICOM, with a built-in 4KB dual-word static memory. DM900C supports 10Base-T and 100Base-TX, compatible with the 802.3u Ethernet protocol.
The ETH interface speed is 100M, which is standard. Compared to the Raspberry Pi 2, it adds WiFi and BT functionality, while the RPI only introduced wireless connectivity with the RPI 3.
Other Interfaces
The Ci20 also provides several other common interfaces, such as an infrared receiver, JTAG, Camera, HDMI interfaces, etc. The power interface is a standard DC-Jack, with a default input voltage of 5V, interface specification of 4mmX1.7mm, and voltage polarity of center positive and outer negative. The only accessory provided is a power cable, and a 5V/1A or higher power adapter needs to be supplied by the user.
The Ci20 development board also features RPI-compatible GPIO interfaces, 26 pins, with a standard spacing of 2.54mm.
Power On and Performance Testing
The Ci20 is powered by a 5V DC supply, using the included power cable connected to an external 5V DC power adapter, along with a network cable, HDMI monitor, keyboard, mouse, and other peripherals, allowing you to start experiencing the Creator Ci20.
The Ci20 offers flexible boot option configurations. In addition to booting from the NAND-based system, it can also boot from SD cards or USB storage devices. By configuring the combinations of JP3 and SW1 on the development board, users can flexibly choose the system stored on different devices. The following image shows the available boot option configurations, with JP3 defaulting to boot the system from NAND. The factory-installed DEBIAN 7 system is pre-loaded on NAND, but DEBIAN 8 also supports Ci20.
The HDMI interface is connected to the monitor through an HDMI converter to a VGA display. It is unclear whether this issue arises from the HDMI converter’s compatibility or the Ci20 development board’s hardware driver. After powering on, there was no output on the VGA display, so the following test image was obtained through remote access.
After configuring the remote desktop connection and waiting a moment, the desktop appeared. What is this? It is the XFCE desktop, which is surprisingly not the customary LXDE.
It turns out that the LINUX distribution is DEBIAN, rather than the usual UBUNTU. Hmm, not following the usual path! Theoretically, DEBIAN should be more rigorous in testing than UBUNTU, so its stability should be slightly better.
XFCE is considered an old-school lightweight desktop system. Compared to LXDE, it seems to be used more frequently on DEBIAN, though these are all personal preferences and customizable.
The system does not come with OFFICE or other office software by default, only providing the Iceweasel browser. Additionally, to facilitate remote desktop access, VNC Server is installed by default.
Network configuration can be managed using the network management component provided by XFCE. By clicking on the network icon in the taskbar, users can view and connect to the respective networks.
Let’s conduct a simple performance test on the Ci20 using the sysbench platform.
First, let’s check the CPU information,
It can be seen that it is indeed a dual-core CPU, with the CPU model being Ingenic Xburst V4.15 FPU V0.0.
Next, we will test the CPU’s performance with the instruction test,
During the test, the CPU on the Ci20 only has two cores, so we specify two threads to test performance. In fact, it is also possible to open four threads, but that would not make much sense. The RPI 2B integrates four cores, and since the core frequencies differ from JZ4780, this comparison cannot fully reflect the specific performance.
Below are the CPU test results corresponding to RPI2, using a four-thread test mode. Aside from the thread count, all other parameters are consistent.
It can be seen that the CPU test performance is basically comparable, with RPI2’s performance slightly higher, but it can be largely ignored.
Next, let’s compare the memory performance of both, starting with the test data from Ci20.
The memory performance test results for RPI2, with the same test parameters, except for the thread count set to four, show a significant improvement in memory performance.
Finally, let’s test the performance of the FLASH storage. From the image below, it can be seen that the performance of the built-in EMMC storage is indeed average, which can be a limitation when processing large amounts of stored data!
RPI2 uses a SANDISK 16GB storage card for comparison, rated CLASS 10. Below are the testing results with identical parameters. The differences are very clear.
From the hardware test results, it can be seen that the CPU performance is basically comparable, but regarding memory and storage capabilities, since the number of threads used for testing is not entirely consistent, the comparison of memory and flash storage is for reference only.
Software Toolchain
When developing software on a CPU based on the MIPS architecture, it is necessary to use a MIPS-specific toolchain to compile the code. However, most LINUX distributions include corresponding toolchains for users to use. The factory-installed LINUX distribution for Ci20 is DEBIAN 7.5, with the corresponding GCC version being GCC 4.6.3.
Code can be compiled directly on the Ci20, eliminating the dependency issues of cross-compilation. Below is a simple Hello World program to review some details of the toolchain.
Details of the compilation process. Apart from the differences in the toolchain, the compilation process is not significantly different from ARM architecture. Additionally, programs obtained from the DEBIAN official software repository can be directly used on the MIPS platform, as the LINUX distribution helps solve this issue.
To further understand the internal details of the generated code, the readelf command is used to retrieve the generated code header, yielding the following information
Here, a couple of details are noteworthy. One is the CPU architecture, where we can see the MIPS R3000 label; additionally, the byte order of the program uses little endian. Finally, the program’s Class is ELF32, indicating that this is 32-bit code since the CPU is also 32-bit. These factors are essential to consider during software development.
Ingenic also provides corresponding SDK development documentation, which includes cross-compilation toolchains and specific SDK low-level software packages for users.
Conclusion
Overall, the Creator Ci20’s advantages lie in its relatively complete hardware configuration. Although the performance and parameters of each hardware component are not the best, they are practical. Moreover, it features a MIPS architecture CPU, which is domestically produced (if this can be considered a point of pride). It serves as a good option for learning and understanding MIPS architecture-related knowledge, such as studying the RISC instruction set, which is entirely different from ARM architecture, and comparing the differences between big-endian and little-endian formats. The perfect combination of ETH/WIFI/BT allows for a complete understanding of the communication framework, and the CPU performance is quite decent, making it a reasonable choice. Additionally, aside from the Loongson Zhilong, there aren’t many other options on the market based on the MIPS architecture!
However, the biggest drawback of the Creator Ci20 is its price; RMB 550 can buy two of the latest RPI 3! Furthermore, compared to the RPI, it is entirely one-sided in terms of software ecology and user base.
So, if you are a die-hard fan of MIPS, you might as well spend the money!
References:
Creator Ci20
JZ4780 CPU
RPI Official Website
Special Recommendations
I2C Bus VS SPI Bus, which do you prefer?
With this explanation, signals and systems become a piece of cake
Let’s open up the stepper motor and discuss it in detail