Application Design of Multi-service Optical Access Interface Chip GW7980

Abstract: GW7980 is an ASIC chip designed by Beijing Greenway for multi-service optical access platforms. This paper introduces the hardware structure of GW7980 and the basic principles of each module, and gives the implementation method of GW7980 as the core and hybrid transmission of multiple services through a single optical cable.
Keywords: multi-service; optical access; GW7980; Ethernet

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O Introduction With the popularity of user services, the shortcomings of PDH optical transceivers with low bandwidth and few types of services have begun to constrain their development. In order to inherit the advantages of PDH, it can provide greater transmission bandwidth and more service interfaces at lower cost, satisfying various business needs such as voice, video, data, and Ethernet. Beijing Greenway Company has launched ASIC chip GW7980 which can realize multi-service optical access platform. The GW7980 can mix and transmit multiple services on a single fiber, thus solving the unified access of large users and multiple services at a low cost, and can uniformly maintain and manage different services. Thereby, a multi-service optical access platform is conveniently constructed.

1 GW7980 features GW7980 is the core device for multi-service optical access system. Its PDH mode can support 2 groups of 6E1 to 2 16 MB multiplexing, each with 16 MB line rate; and its E+E mode. It can support 2 channels of 8.448 MB to 16 MB of multiplexing, or support 8.48 MB of signal independent local loopback function. GW7980 can support 2 non-framing bandwidth adjustable V. 35 interface, its setting bandwidth is 2nx64 KB, n=0, l, 2, 3, 4, 5.
The GW7980's two working modes support 1+l fiber protection; each channel transmits E1's 16 MB channel to provide two 264KB synchronous rate transparent data channels for use as a network management channel or a common data channel. One of them can be used as a business telephone channel; each channel of 16 MB channel can also provide one 8-byte dedicated data channel, which is used as the internal channel of the network management (can be completed by reading and writing the internal registers); and each 16 MBA channel can be used. Provides 32-bit (4 bytes) high-pass transparent transmission channel for 32-bit independent information transfer (can be done by reading and writing internal registers); at the same time, the device can also operate in two modes. The optical port error rate indication and the LOS and AIS alarm detection indication function of the E1 port are provided. When the line side of the two working modes is light and the frame out of synchronization alarm occurs, the corresponding E1 port will output an AIS alarm signal; The device also features an El channel error test.
The GW7980 has a CPU interface bus with standard MCS-805l microcontroller timing. The general configuration mode and the collection of various status information can be completed through this interface. Some configurations can be set either by pin or by internal registers. The default state of these internal registers is not enabled. The related configuration method is based on the setting of the pin. When the CPU is set to the enabled state, the setting of its external pin will no longer work. In this case, the configuration mode is determined by the setting of the internal register.
Figure 1 shows the main functional schematic of the GW7980.

2 main functions of the system
2.1 System Framework The GW7980 has two modes of operation. Both support 1+1 fiber protection. The GW7980's "WORK_MODEI" pin is set low to implement the E+E mode of operation of the GW7980. Through the E+E mode of GW7980, Ethernet MII interface data and multi-channel El data can be mixed and encoded to form 10 channels of 16.896 MB parallel data, and then external parallel strings, serial and commercial devices and optical devices can be combined to form an optical transmission system; Its 1+1 fiber protection function adopts dual-issue selection mechanism, the transmission interface is one parallel interface, and the receiving interface is two parallel interfaces. One receiving interface is the main channel (A optical port), and the other receiving interface is standby. Channel (B optical port). One 100/10 Ethernet signal can be transmitted through the external Ethernet PHY chip; 35 interface conversion chip, can transmit 2 unframed / bandwidth controllable V. 35 signal (DCE working mode); In addition, through the external E1 interface chip, it can also transmit 8 E1 signals; at the same time, through the external CPU chip, it can realize the functions of management and alarm of GW7980 chip. Figure 2 shows the system connection diagram of the GW7980.


2.2 Optical Interface Circuit The optical interface circuit of GW7980 can be composed of line multiplexing coding circuit, line tap decoding circuit, branch transceiver connection complex/drop circuit, and overhead auxiliary channel circuit. Its function is to inversely transform the quasi-synchronous signal, and then enter the positive code rate adjustment, and then send the code-adjusted signal to the multiplexer for time slot allocation, and then enter the synchronous multiplexing code via the enable switch. Device.
The synchronous multiplexing encoder can perform multiplexing, encoding and framing of the transmitted optical line signals, and then outputs 10 channels of 16.896 MB parallel data through the scrambling code. In addition, the overhead channel can simultaneously insert a frame code (synchronization code), a monitoring code, a service code, and a data code. The synthesized 16-channel 16.896MB parallel data is sent to the optical driver component by the high-speed transparent channel code stream of 260 MB after passing through the external serial and high-speed interface circuit, thereby driving the DFB-LD illuminating device to Converted to an optical signal for transmission.
The tapping and decoding circuit converts the optical signal into an electrical signal by the light receiving component, and then amplifies and serializes the high-speed interface circuit to convert the 260 MB high-speed transparent channel code stream into 10 channels of 16.896 MB of parallel data, and then passes through The timing circuit performs clock extraction and shaping amplification, and finally inputs the signal to the complex/splitting circuit and the encoding circuit for inverse transformation. The optical interface connection diagram of the GW7980 is shown in Figure 3.


The GW7980 supports the statistics of the bit error rate of the optical transmission channel, and provides two-level alarm information of 10-3 error code and lO-6 error code. It can not only give the statistics of the bit error rate in real time, but also perform the clearing operation (that is, reset the error statistics result and restart the statistics); the optical port alarm of the local end includes: no light, frame out of step, 10-3 Error codes, 10-6 error alarms, etc., the GW7980 can transmit these alarm states to the far end so that the remote end can read these alarm states through registers. The setting of the internal register can make the received signal select whether to use the primary channel or the alternate channel, and can realize the switching of the protection switching.
2.3 V. 35 interface circuit V. GW7980 The 35 interface is mainly for the working mode of DTE and DCE. She provides the legs that send and receive data and send and receive clocks respectively. Its external connection only needs to comply with ITU-T V. 35 interface standard interface chip, you can provide standard V. 35 synchronous data interface, V. GW7980 35 interface connection diagram shown in Figure 4.


V. The clock selection mode, rate setting and other settings of the 35 interface can be completed by the internal registers of the GW7980. The setting status is as follows:
(1) Delayed phase relationship between clock and transmit and receive data V. The phase relationship between the transceiver clock timing selection and the data clock of the 35 interface can be selected as follows: the transceiver clock is delayed by about 60 ns, no delay, and inverted. The default setting is “the transceiver clock is delayed by about 60 ns for transmitting data. Inverted"
(2) V. 35 interface data loopback setting V. The default setting for 35 interface data loopback is not loopback, in fact. V. 35 interface data loopback is similar to the local loopback of the E1 interface data, and the remote loopback is implemented by the remote loop of El;
(3) Rate setting V. 35 interface data can be set to a bandwidth of 2nx64 KB, where n can take 0, 1, 2, 3, 4, 5, the default setting is N=5.
2.4 Ethernet Interface Circuit The GW7980 provides a standard MII interface for Ethernet. When designing, it can provide lOOBT/10BT interface through external Ethernet Phy device, and can adapt to 100 MB, 10 MB full-duplex, full-line mode. The Ethernet interface connection diagram of the GW7980 is shown in Figure 5.


2.5 E1 interface circuit The El interface part of GW7980 in E+E working mode is composed of 8 conforming to ITU-T G. The E1 interface circuit of the 703 protocol is composed of eight E1 signals. The E1 interface connection diagram of the GW7980 is shown in Figure 6.


The El HDB3 interface pattern conversion circuit is based on ITU-T G. 703 is recommended to specify the design, the code is the specified pattern of the electrical signal transmission interface between the product and the product. It is a third-order high-density bipolar code. This three-level code cannot be processed in an optical circuit, and thus an interface pattern conversion is required to convert it into a two-level NRZ code.
The GW7980 has a built-in digital clock recovery circuit. The circuit adopts advanced digital clock recovery technology, which can be extracted from the data signal of the El line without the need for an off-chip clock recovery circuit. Therefore, the peripheral circuit composition is relatively simple, and the generated clock signal has the characteristics of accurate frequency and small jitter. . The GW7980 can read and write its internal registers through the CPU interface control bus, and monitor the E1 interface. It can also obtain the lost alarm signal and bit error rate of each E1 data through the query register.

3 Application Solution The main function of the GW7980 is to multiplex multiple services and then transmit them over long distances through optical signals. It can be used for signal transmission between various switches, mobile base station connections and various public/private network connections. Thereby, system access of integrated services such as voice, data, and images is realized. Figure 7 shows a schematic diagram of its main application.

4 Conclusion GW7980 is an ASIC chip that can realize the design of multi-service optical access platform. It can save the PDH, PCM, protocol converter, Ethernet switch and other equipment required for traditional access network transmission. It can solve the inconvenience of operators from product selection and procurement to machine room management and equipment maintenance and repair. The GW7980 not only meets the management requirements of “centralized management, layered maintenance” of the operation and maintenance department, but also has rich service interfaces and flexible configurations. Therefore, the GW7980 will have a wide range of applications in the access network.

Pic of LED Power Supply:

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Basic Parameter: 

Power: 30W / 60W / 100W / 150W / 200W / 250W

Input Vol.: 100-240V

Output Vol.: 12V

Input Frequency: 50-60Hz

Efficiency: ≥85%

Working Temperature: -40-70℃


Applications:

Outdoors. 


Features:

1. Adopting Constant Voltage Operation.

2. Open circuit and short circuit Protection 

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4. 100% full load aging test 

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6. Have OVP/OCP/SCP/OTP protection function


Installation:

Lock Screw.


Warranty:

3 years or 30,000 hours.


Note:

1. Please will power supply installed in a well-ventilated place, to ensure that the environment temperature is approproate.

2. Don't allow hot-line work, check wiring without short circuit again electrify!

3. When the power supply working, Don't touch the exposed metal parts, Prevent to get an electric shock!

4. If failure, please don't self-repairing. If you have any questions,please contact suppliers.


A coutesy reminder:

1. According to the consultant's recommendations, kindly tips shall be increased in specifications and contract review.

2. Please pay special attention to power usage environmental conditions, regular inspection and maintenance to avoid safety hazard.


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