IP-Camera design based on FIC8120 and PoE

introduction

In today's digital Internet era, any electronic device is striving to develop in the direction of digitalization and networking. The Internet is bringing us closer and changing our lives. The field of surveillance is also developing rapidly towards networking without hesitation, and the networking development of cameras is also unstoppable. [6] IP cameras will make long-distance video surveillance possible, which will change the dilemma of the original distributed analog cameras that cannot achieve low-cost long-distance transmission!

To meet the needs of distributed single-camera long-distance transmission, modern IP cameras must have the characteristics of small bandwidth, high image quality, low cost, low power consumption, etc. This system adopts digital CMOS digital image sensor, MPEG-4 high compression ratio VGA/CIF ARM-SoC and Si3401 Ethernet power supply and Ethernet device controller to propose a full digital real-time network camera solution to meet the current and future monitoring needs.

Overall hardware architecture

The whole system consists of CMOS video acquisition, compression encoding, video processing, Ethernet power supply and Ethernet data communication. From the front end to the back end, it goes through several processing steps such as "lens OV7660 → FIC8120-SoC → PoE/Network".

According to the different needs of users, we can choose the corresponding lens group. The analog information obtained from the lens is digitally collected through OV7660, and then transmitted to the subsequent processing components by this CMOS sensor.

1. FIC8120-SoC related design

FIC8120 is a highly integrated SoC designed by FARADAY Technology, a subsidiary of UMC. It features MPEG4/JPEG video image acceleration, low cost and low power consumption, and is based on the ARM922 core. [1]

As the CPU of the system, FIC8120 captures the ITU 656 YUV 4:2:2 VGA format digital image signal output by OV7660[5] and transmits it to the external SDRAM via AHB bus DMA. At the same time, it is transmitted to the internal MPEG-4 Codec for encoding. After the encoding is completed, it is sent to the Ethernet MAC for output from the network port after the relevant processing selected by the user. [page]

This design supports the commonly used resolutions and frame rates of VGA (640×480) @30fps and CIF (352×240) @30fps in the industry for compression encoding and real-time recording, and has efficient motion detection technology. The use of motion detection technology allows recording to be triggered only when a moving picture is captured, thereby greatly reducing unnecessary disk space. The Codec also supports a number of advanced technologies such as hardware DCT/IDCT, quantization/inverse quantization, and variable-length coding, which significantly improves encoding efficiency and significantly reduces power consumption. The system also makes full use of the built-in 100K gate MPCA (similar to FPGA) of FIC8120 to achieve practical OSD (character overlay) and other functions.

In addition, FIC8120 has rich peripherals and IO, which also provides great convenience for future system upgrades. Here mainly reserved audio compression port (I2S/AC'97) and CCIR601/YCbCr/RGB video input, etc.

2. Si3401 PoE power supply design

For low power consumption and ease of use, and after verification of power supply voltage and power, this system uses Silicon Labs' Si3401 Ethernet power chip. [3] Power over Ethernet (PoE) is an IEEE 802.3af standard for transmitting power through Ethernet cables. 802.3af supports two power supply methods, namely, power supply for spare wire pairs and power supply for signal wire pairs. In order not to change existing network equipment and adapt to future network equipment, this system uses the spare wire pair power supply method. [4] Ethernet connects the signal line to the physical layer (PHY) through a network transformer and transmits it to FIC8120, while the other spare wire pair is connected to Si3401 for power supply adjustment. Since IP-Camera is an independent powered device, this design configures Si3401 into a non-isolated DC-DC adjustment mode and makes it output a 5VDC primary power supply. Due to the voltage requirements of the CMOS image sensor, CPU, and peripherals, this design uses LM1117 to step down 5V to 3.3V-1A. Considering that FIC8120 requires a low-noise and high-precision 1.8V core voltage, I used the TPS71229 ultra-low-noise 250mA dual-channel LDO, which can not only provide a reliable and stable 1.8V-250mA, but also provide the 2.5V voltage required by the CMOS image sensor through the configuration of the peripheral circuit.

System software design

[page]

In view of the ARM922 architecture of FIC8120, the system transplanted FIC8120 to the low-cost Embedded Linux 2.4.19, and made some cuts and optimizations based on FIC8120 and IP-Camera. The system uses the standard GNU tool chain.

Based on FIC8120, we first encapsulated a board support package (BSP), which includes CPU initialization, memory management, various peripheral drivers (Ethernet, etc.), Linux Kernel initialization, interrupt processing, clock management, watchdog, I/O system and file system, etc. BSP is also similar to the initialization and hardware abstraction layer. The upper-level application makes related calls through the API provided by BSP. The system initialization program also needs to complete the system's network allocation, video-related parameter configuration (including video resolution, bit rate, frame rate, fixed bit rate/variable bit rate, etc.), and shut down unused peripherals to minimize power consumption.

In addition to BSP, the software system also includes the key TCP/IP and UDP protocol libraries of IP-Camera. The network protocol provided by FARADAY is quite complete and has high real-time performance. [2] Application software includes file system management, network services, email sending, file transfer, detection and alarm, etc. The network service program sends the video to a certain port on the network for access by other network devices (such as remote clients); when the email sending and file transfer programs detect a moving target and need to alarm, they capture the picture at that moment and send it to the email server or file server; the detection and alarm program determines whether the moving target in the video needs to be alarmed according to the rules set by the remote host.

The application also includes a Web Server. With the dedicated Media Player program, the application software can complete the processing of external service requests according to the HTTP protocol, send MPEG4 streams to Ethernet, process external control instructions, motion detection alarms, etc. After connecting to FIC8120 through the IE browser, you can make relevant settings for FIC8120 on the page, such as network configuration, multi-stream monitoring, SMTP service, FTP server, video quality, motion detection, administrator password management, etc. [page]

Conclusion

This IP-Camera uses a LAN to remotely access the Web Server under the configuration of VGA resolution, maximum bit rate 2Mbps, frame rate 30fps, variable bit rate, and motion detection, and performs operations such as preview, recording, playback, and settings. The quality is excellent, and the storage space occupied by the recording is controlled within an average of 500MB/Hour; the overall power consumption of the system is 3-7W, and the power efficiency is >80%. This system is extremely suitable for widely distributed medium and large monitoring sites, and only one network cable and a small number of Switch/Hubs are needed to complete the layout; it can also be recommended for application fields such as the transformation and expansion of existing equipment. There is no doubt that this IP-Camera system is one of the preferred solutions for digital and networked monitoring today and in the next generation.

References

[1] FARADAY. FIC8120 MPEG4 Codec Platform SoC Datasheet. March, 2006

[2] FARADAY. Faraday Linux Software Development Kit for FIC8120. October, 2005

[3] SILICON LABS. Si3400/Si3401 Datasheet. December, 2006

[4] SILICON LABS. Using the Si3400 and Si3401 PoE PD Controllers in Isolated and Non-Isolated Designs. AN296. December, 2006

[5] OmniVision. OV7660/OV7661 Datasheet. 2004

[6] Hou Junhua, Hu Jinyan, Su Boshi, Chen Feng. A new embedded MPEG-4 DVR system design. Microcomputer Information. 2006, Vol.22-No.14, P187-189

Innovative ideas:

This paper designs the industry-leading IP-Camera with full digital video surveillance and Ethernet power supply as the core. This system is a modern digital network camera solution, which is very suitable for the field of distributed video surveillance. Its low power consumption, low cost and easy maintenance also put forward a new development direction for the next generation of video surveillance.