Schematic Editor

To launch the schematic editor click on “Top Schematic” in the project manager.

Placing parts

To place parts, open the part browser either by typing p p (place part) or clicking on the corresponding icon in the project manager. Once a part has been placed, it can be replaced by a part of the same entity by selecting it and using the “Assign part” button in the part browser window.

Nets and net segments

Unlike some other schematic entry tools, horizon’s actually knows about nets and isn’t just about drawing lines that will eventually be transformed into nets when generating the netlist. A net may be represented by one or more net segment. A net segment is a set of net lines, junctions, pins, etc. all connected by net lines. Since the editor tracks which net segments belongs to which net, it provides feedback when an operation is about to merge two nets.

So when you see a net in the property editor after selecting a net line, the net in the property editors is the “whole” net and not just the net segment. That’s why renaming a net doesn’t change connectivity. To connect the pins on a net segment to a different net, use the “Move net segment to other/new net” tool.

A net label just displays the name of the net it is connected to and doens’t set net names. To alert you about inconsistencies in the schematic that could result in unexpected connectivity, the schematic editor places warnings on the offending items.

Power symbols

The easiest way of creating a power net is using the “Manage Power Nets” Tool available from the hamburger menu. Then, use the tool “place power symbol”, to place a power symbol for this net. Power symbols force their net on the connected net segment. You can select from three styles of Power symbols in the aforementioned tool. The Antenna and Dot symbols can be placed either pointing up or down. The GND symbol can only point downwards.


To group related nets, use Buses. After creating a bus, add members to it. You can either assign existing nets or automatically name the newly created net by clicking on the arrow button next to it.


To create a differential pair, select the two nets you want to become a pair and run the “Set diff. pair” tool. You can also select one net and you’ll be asked for the other net. To decouple the nets, use the “Clear diff. pair” tool. It’s recommended to assign both nets a netclass such as “100diff” so you can match them in the rules.

To board

To facilitate placing packages on the board, simply select the corresponding symbols and hit “To board”. This will switch to the board editor and launch the “place package” tool with the packages for the selected symbols. Note that you may need to reload the netlist in the board editor before doing so to make the board editor pick up new components.


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