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Several Connection Line Methods for Altium Designer Schematic


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First, direct connection.

This is the simplest connection method, so there is no need for much explanation. Please refer to the following figure for details.

direct connection

Figure 1

Second, net Label.

Net labels are used to identify networks, and networks with the same name are connected together. The use of network labels can effectively reduce the use of connection lines, making the schematic diagram concise and clear. As shown in the following figure, its electrical structure is the same as the direct connection in Figure 1.

net Label

Figure 2

The range of action of network labels can be changed to global in Project →Project Options →Options tab, so that network labels can be applied to other schematics in the project.

Note that the network labeled with a network number is not connected to the network connected to an off sheet connection (you can see it in section 5). That is, when one network is labeled with a network number and another network is connected to an off sheet connection with the same name, although the same network name will be displayed when hovering over the mouse, it is actually two different networks. At this time, compilation will report a duplicate name error.

When using wire harness connections (you can see it in section 6), the network label will only apply to the interior of the schematic and cannot be applied to other schematics. (Because hierarchical schematic design is actually circuit modularization, just like functions in programming, we always hope that external functions can only call function interfaces (wire harness ports) and hide internal temporary variables (network labels).

Third, the bus.

the bus

Figure 3

Pay attention to the network label placed on the bus and the naming format of the bus port: BUSAME [START..END], with two English periods between the starting and ending numbers, instead of the commonly used colon. There is no limit to the number relationship between start and end, that is to say, naming forms such as bus [0..7] and bus [7..0] is acceptable.

The bus is mainly used for standardizing schematic diagrams, allowing readers to clearly see the connection method of signal lines, but there is no actual electrical connection, and the actual electrical connection is still achieved through net label.

Fourth, off sheet connector.

When the schematic diagram is so large that it cannot be fully drawn on a single drawing, it is usually divided into multiple separate drawings. The network between different drawings can be connected through the network labels mentioned in Section 2, and a more standardized approach is to use off drawing connections to off sheet. The off sheet connections with the same name belong to the same network.

There are two types of off sheet connections, and they are Right and Left, which do not have actual electrical functions, but can be used to identify the input and output directions of signals, making the schematic clearer.

off sheet connector

Figure 4

Due to the disconnection between the off sheet connection and the network label, if using a network label, the following format should be used:

network label

Figure 5

The last, signal harnesses.

When conducting large-scale schematic design, the conventional planar design method (multiple parallel schematic diagrams) will be difficult to effectively manage the schematic diagrams. In this case, hierarchical schematic design (multiple schematic diagrams form a tree structure) will be used instead. The idea of hierarchical schematic design is similar to modular programming, where each subgraph corresponds to a circuit module, and the interface of the module is the wiring harness connection. Due to each subgraph being encapsulated into its corresponding circuit module, it is very convenient for us to reuse circuit diagram. The following diagram shows the wiring harness of a UART port:

the wiring harness of a UART port

Figure 6

Sometimes we hope to also use the functions of the bus when using harness interfaces, but due to the lack of actual electrical connections on the bus and the inability of network labels to cross diagrams when using harness connections, it is not possible to achieve connections like the following:

not possible to achieve connections

Figure 7

However, wire harness connections can be nested, which can be designed in the following form, allowing for bus like connection line management through wire harnesses.

wire harness connections can be nested

Figure 8

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