This simple project is to illustrate how to use the Bus Entry/Exit and Bus schematic symbols.
The easiest way to learn how to use these symbols is to read the rest of the project description below and then play with the schematics to get used to using the symbols.
What you draw in a schematic using the Wire tool that is just a user friendly graphical way of showing that two or more nodes (device pins) of a circuit are connected together.
In EasyEDA, all nodes that are to be connected together in a schematic are in fact joined by a unique net name.
Netnames are automatically assigned to nets in the schematic as you draw it. The wire is just a graphical way of assigning the same unique netname to all the nodes that it connects.
So, for example, all the nodes connected to a positive supply are assigned one net name and all the nodes connected to a negative supply rail are assigned a different net name.
If you then decide to add a netlabel yourself to a net then the name that you assign to that new netlabel overwrites the original automatically assigned net name.
If you place the same netlabel on two different nodes then they are connected together, even if they are on different devices on different sheets.
Once you understand that, it is easy to use the Bus Entry/Exit and Bus tools.
To create a bus all you do is place an array of Bus Entry symbols so that one end can be drawn across by the Bus tool with the other end near the array of component pins that you want to connect into the Bus. Then draw a short length of wire from each component pin to the free end of each Bus Entry symbol and place a uniquely named netlabel on each short length of wire.
Repeat the same steps for every pin that you want to exit the Bus at the other end.
The Bus itself does not have to be drawn all the way between the start and end points. It is even possible to draw isolated subsections of the Bus with Bus Entry/Exit symbols to wires with net labels wherever it is graphically convenient to add or remove wires from the bus.
The Bus Entry/Exit and Bus symbols however are just a way to help make a tidy, easily readable schematic. It is the connectivity through netlabels that allows Busses to be drawn split up in sections so that a Bus can start on one sheet, end on another and with break out points on other sheets if required. So it is equally possible to connect busses and individual nets (a set of nodes assigned with the same netname) using just netlabels.