I want to have just entered the rhythm. When I interviewed, the router was asked to have the difference between the switch, because it lacks an answer in the answer. On the way, the router needs to be configured to access the Internet. You need to configure the broadband account password in the home, so that the route automatically completes the dialing to access the Internet, and the switch is not available. After working, I have done this piece, I thoroughly know the router and switch, I don't know my real. Routers and switches work in different layers of the network communication OSI reference model, the router works on the network layer, while the switch is in the data link layer.
Figure 1 OSI reference model
Then, what is the difference between the network layer and the data link layer, can be intuitive from the figure below, each dashed box in the figure represents a subnet, 3 subnets in the map, and the network segments are 145.13.3.10, 145.13.7.0, 145.13.21.0, each subnet can be used to use the switch to perform data exchange, but between the two subnets, data exchange must be performed by the router, and three subnets are connected in the router R1.
Figure 2 Subnets and routers
The router is a very mature product, and it can be bought by the cheap 30 pieces, but the middle and low-end products on the market feel very unused. If you don't think of the thunder outside, you may damage the router. Today, I share a hardware design of a industrial-grade router, what is industrial grade, simple understanding, more reliable, more resistant to the general product. If you use an EMC index to describe, you can see different from antistatic capacity. The consumer router has an anti-static capacity of ± 6kV. The industrial router has an anti-static capacity of ± 8kV and does not occur hardware damage that cannot be recovered. Military and medical routers have higher resistance to static requirements, at least ± 8kV or more, and data loss occurs when working properly. In the design, the detailed description How to make the design reach the industrial level.
Before the description of the design details, simply explain this chart tool, because it is a little special, there may be some small partners haven't used it yet. This tool is Easyeda (unknown little partner can be Baidu Easyeda), it is a bit like a hardware engineer's old friend PDM system, we can upload design, you can view these design online, very good hardware The open source of the design is easy to view, useful to use it. But it is far more than going uploaded and views this simple, it also supports online design, seeing the value of others can directly copy into personal space for the secondary design. Also, every design is the same as the picture of the circle, we can praise the design and publish a comment, encounter the design, and can also directly leave a consultant, greatly enhance the effect of open source. It is not only to give the design, but also allows the user to quickly use, a bit like software open source.
Used quite long, I feel that Easyeda is very good to design open source support for hardware. It is a bit similar to Github, but it is focused on open source hardware design, and personal feelings is much better than GitHub's people (GitHub only English version, natural is for the big gods Create it). GitHub focuses on software's open source, with very powerful version management functions, while Easyeda focuses on hardware design, and also has good project management and version management functions.
As described below, some drawings may not be clear enough, interested partners can log in to www.easyeda.com to search for the Router keyword (I have tried, you can find). The specific project link is as follows:
Https://easyeda.com/yuweijian615/router-993df76b3a6d425f825099cbf9764476
The entire project is as follows:
Figure 3 Project Management
Now described by one according to the order of the project document
(01) Power-ASCII
Let's talk about the name of the file, Power description This paper draws the power circuit. ASCII describes the Easyeda file format, which can be derived in the AD9 picture software. details as follows:
Figure 4 Power supply circuit
The design involved is not much, really because the power supply is concentrated, pay special attention to the power requirements of the power supply, the 5V DCDC used in the design can output the maximum 3A current, and there is enough margin when it is running. Because the higher EMC resistance is to be reached, if the arrow is arrow, it is distinguished from the power supply, and the two places use the magnetic beads or conventional capacitance isolation. Which isolation method actually uses the specific test results, design The position is reserved for both components. The interference signal is moved away from the protective ground when the interference occurred. The topology of the entire manner is as follows:
Figure 5
(02) RTL8309-ASCII
This name is named with the chip model, mainly drawing the switch chip related circuit, as follows:
Figure 6 Switch circuit
Because this router program only has a network port, it is a WAN a LAN, which will be said in the next drawing, so use a RTL8309 to expand, this time has expanded 7 LAN ports, the next drawings It is also said in it. The communication frequency of the network part is very high, the decoupling capacitance at the power point is essential, and it is close to the power pins, and it is very relevant to the products of the product of the manufacturers. Many times, the Internet is online. Slowness is not enough to have the bandwidth of your home, but the packet loss rate you use, resulting in the efficiency of the entire communication.
RTL8309 is a very mature switch chip of Realtek, as follows:
Figure 7 RTL8307 internal function block diagram
Seeing the small crab sign in the upper right corner, it is very familiar, yes, in fact, most of the audio decoding chips on the PC and the network chip are the products of this company. We can see this eye-catching icon when installing the driver.
(03) Connector-ASCII
As you can see from the name, I will put the interface in this drawing, as follows:
Figure 8 RJ45 interface
This is mainly placed in the drawings, and each network input is isolated using the network isolation transformer, isolating the intermediate tap of the transformer, using TSS tube (a TVS tube) Protective components) Establish interference signal pathways to protect PE. When using an isolation transformer, it is necessary to note that one end of the common mode suppression is to be external, that is, the 14, 16, 11, 9 ends below the RJ45 interface, the internal structure of the isolation transformer is as follows:
Figure 9 Network Transformer internal schematic
(04) ESD-LED-ASCII
This will protect the protector and the LED indicator, as follows:
Figure 10 Protective devices and LEDs
The light is a protective element to draw a drawing. It is not easy to achieve industrial-grade EMC resistance. The market is not a few, and there is no way to decouple capacity, and it is not used to increase so many electrostatic protection. The component is, this is money. Each RJ45 interface is an LED indicator, 7 LAN ports, 1 WAN port, convenient to view the network connectivity.
(05) RT5350MOD
This is another blueprint named by chip model, and RT5350 is a commonly used router master chip, and this time I bought the module I bought, so I named RT5350Mod, as follows:
Figure 11 router module
The RT5350 is a common router master chip with WiFi features. It is best to use it when DIY is used. Although the router is more mature (usually using OpenWRT firmware), I still have to spend a lot of effort. The order in the figure above is determined according to the module I bought, if the small partner does not buy the same module, you can adjust according to your module. The module is prompted to reserve a USB string circuit Fe232RL. The module of the RT5350 on Taobao is really a lot, as shown below:
Figure 12 RT5350 module
The schematic is so much, it is not difficult, mainly to pay attention to EMC design. Next, describe the PCB Layout. First look at the renderings, Easyeda's renderings are similar to the actual model, quite realistic, as follows:
Figure 13 Positive effect diagram
Figure 14 Back surface renderings
There are two floors in the PCB map, as follows:
Figure 15 Top of the road chart
Figure 16 underlying circular diagram
There are several attention: 1, pay attention to the placement of the protective element, Figure 14 shows the relatively clearer, to be placed in the input direction of the signal; Or the capacitance is isolated; 3, the RJ45 and the copper foil that isolates the bottom of the transformer should be hollow. Finally, share a finished chart for everyone, the picture is a bit ugly, please automatically ignore the fixed white glue, as follows:
Figure 17
All the contents of the design are so much, you can get the design details in my sharing project, don't forget to praise.
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