FreePCB Editor to Edit and Layout PCBs


Most free or low-cost PCB editors are either limited by pin and layer limits, or have bugs that make them difficult to use. So we have found a better one for you. Read this article to know more about the PCB editor called FreePCB

Pankaj V.

FreePCB, as the name suggests, is a free open source Windows program for editing and laying out PCBs. It is a handy tool capable of doing professional quality work, while at the same time remaining very easy to learn and use for beginners.

FreePCB comes with an intuitive GUI and options that allow you to perform almost any task related to PCB designing. It can easily be used for serious designs too, as it can handle multiple (up to 16) copper layers and comprises a Footprint Wizard and Footprint Editor for guiding the process of creating or modifying your footprints.

Fig. 1: FreePCB

5B3_BoxYou can configure the footprints using the various functions that come bundled with the software. I also found an interface to the FreeRoute autorouter program, which relieves you from manually routing each trace in your design, thus making the design process much easier. Let us take a deeper look at the key features.

Key features
The other PCB tools, including some paid ones, can be far too intimidating and overly complex, but FreePCB is quite easy to use and learn. There are enough features in this tool for your PCB design requirements. Let us look at each of the important benefits and how they stack up.

User-friendly tool. Apart from the obvious PCB design functionality, some built-in features also exist which make working with FreePCB user-friendly. To list a few, we can start with the ‘auto-save’ feature. the auto-saved files are stored in a subfolder of the project folder, with incremental file names generating automatically.

File handling gives the advantage of re-usability, groups can be saved as project files and you can paste a project file as a group into another project. Automatic functions such as Check Traces clean up traces for you by combining collinear segments and eliminating zero-length segments. Also, you can make changes in the settings for a pin and applying those to other pins in the Footprint Wizard.

We cannot list all but, using this tool, you will find many other useful features which will make your PCB designing process very easy and efficient.

Footprint wizard and footprint editor. The software comes with a wizard kind of tool that helps you in creating footprints easily, so that you do not have to labour through the process like in some other tools.

Fig. 2: Add/edit part

Apart from the footprints available in the Footprint Library, you can create footprints for a variety of standard packages using this wizard and edit those existing ones using Footprint Editor. You can also add and edit the pins in the footprints, eliminating any limitations that are usually seen with competing products.

Import netlist from any schematic editor. If you already have a favourite schematic editor, you do not have to leave it while moving over to FreePCB. While you can surely generate a netlist within FreePCB, you also have the flexibility to import it from any other schematic editing program that can output a PADS format netlist. Moreover, once you do this, you can then manually place the components and route traces between the pins of the components to continue work.

Design rule checking. Practically there are certain lower limits on trace widths, pad sizes and clearances between copper features and/or holes, called Design Rules which vary depending upon the manufacturing process that you plan to use, should your design be approved for production. FreePCB has a Design Rule Checker which checks your PCB design for compliance with a set of design rules provided by the PCB manufacturer.

Easily share output. The person to whom you send your file does not need to have a copy of FreePCB to be able to view it, as there are multiple ways in which the file can be shared with others for viewing. The tool outputs RS-274X-formatted Gerber file data and a drill file, which you can use to make boards of sizes up to 152cm by 152cm. There also are many options available for Gerber file outputs and dimensions, as per your requirement, which can be viewed in any free Gerber Viewer.

Decent GUI. The main elements of the GUI window are the menu bar, the taskbar immediately below the menu bar and the layer list on the left side of the client area, showing its colour and visibility, the selection mask below the layer list, with options to enable/disable selection of various items, the layout window showing the PCB, the function key menu below the layer list and layout window which shows the available function key commands and the status bar at the bottom.

Setting units and grids. The taskbar contains eight shortcuts for various file and edit options along with five dropdown menus for setting units and grids used by FreePCB—units for selecting sizes in mils or mm for dimensional units, Visible to set the spacing of a rectangular array of dots in the layout window as a visual reference, Placement to set a snap grid for placing parts, text, etc, Routing for setting up a snap grid for routing traces and drawing copper areas and Angle to set a snap angle (in degrees) for routing and drawing poly-lines such as the board outline and copper areas.

Note: When a project is created, the default values for all are copied into the options section of the project file. They can be modified by editing either default file default.cfg in the folder which contains FreePCB.exe or the project file using a text editor.

Layer list. The top vertical list to the left of the layout area is the layer list. It contains all drawing layers that are in use by the project, with boxes next to each layer showing its colour and visibility. If the layer has been made invisible, the square will be white with an ‘X’ through it. Also, you can toggle each layer from visible to invisible by clicking on the square.

Fig. 3: Design rule check
Fig. 4: View/edit layers

The active layer for routing can be identified as one with an arrowhead. You can change the active routing layer by pressing a numeric key on the keyboard, or by clicking on the name of the layer in the list.

Selection mask. The selection mask is below the layer list, with boxes to enable/disable selection of various items. For overlapping items, it may be difficult to make the required selection. here you can use the selection mask to enable or disable the selection of different item types. A green box means that the item type can be selected, while a red box means that it cannot. You can toggle the state of each box by clicking on it.

The netlist
A set of pins which are connected together by lines on the schematic is a net. Each pin in the net is identified by the reference designator of the part containing the pin, the character dot (.) and the pin name. For example, pin 8 on part U5 would be U5.8.

If the schematic was created with a schematic editor, the part list and netlist can be automatically written to a netlist file. Netlist files are available in various formats. You should choose a format which is recognised by FreePCB, such as PADS-PCB. If you are working from a printed or hand-drawn schematic, you will have to manually make the netlist file in a text editor.

Rubber-band lines. When you import the netlist file into FreePCB to start your design, FreePCB will try to find a footprint to match the package identifier for each part, or you can assign footprints manually, or go back and edit the netlist.

Fig. 5: Generating Gerber and drill files

All of the footprints will be placed near the lower left corner of the PCB design area. After loading, connections will appear as rubber-band lines between the pins, called Ratlines. Moving parts will move these ratlines too, and make it easier to manage connections.

Adding parts and nets on-the-fly. Alternatively, you can create a design in FreePCB without a netlist file by using the on-the-fly editing technique. Starting with an empty design, you can add each part, net and connection using the Modify and Add menus. Reference designators and net names will be necessary. This is handy in designing small designs but for larger designs creating a netlist file should be preferred.

Placing parts. Parts can be placed on the PCB by moving or rotating them, as necessary, and the ratlines will automatically be reassigned to minimise their total length. Using a snap grid will make the alignment of parts easier.

Finally, the plot and drill features
FreePCB allows plots of each layer to be exported as Gerber files, which are used to make photographs for PCB fabrication. FreePCB also produces drill files, which specify all the holes to be drilled in the board. You just need to select the files that you want to generate and click on Create Files, which will write the drill files to your output folder. There is also a Panelising section that allows you to select the number of copies to be produced in each direction and the spacing between copies.

Download latest version of the software: click here

The author is a technical journalist at EFY


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