Throughout this document we have spoken about component databases, schematic templates and PCB layouts. All of these are fundamental starting points for your design needs.
In this section of the reference design we however can focus on completed designs, which are ready to be immediately fabricated. With a few changes, or alterations, you can even take these reference designs and make them appropriate for your own custom designs.
With the following reference design, contained in the following file: 8213_design_files.zip, you will find:
- sbRIO-960X daughter card reference design.ms10 (design schematic)
- sbRIO-960X daughter card reference design.ewprj (design layout)
- sbRIO-960X daughter card reference design gerbers.zip (Gerber file output for fabrication)
Reference Design Functionality
This design is a simple counter, which uses the FPGA and Real-Time Processor onboard the Single-Board RIO to light a pattern across a bank of 8 LEDs. This design is similar to a CompactRIO custom module design that is also available as a reference design (to learn more click here to view the online article).
This is a simple, yet functional design that can help you to leverage the Single-Board RIO’s compact and effective design on a custom daughter card.
Reference Design Schematic
The reference design has been broken into various multi-page schematics that allow us to access to various ports effectively. We have utilized the “port” based breakdown of the connector symbols in this reference design.
To open the schematic:
- Open Multisim (Start > All Programs > National Instruments > Circuit Design Suite 10.1 > Multisim 10.1)
- Select File > Open
- Browse to the sbRIO-960X daughter card reference design.ms10 file. Click on the Open button.
- You will see the design ready to view in the Design Toolbox (Figure 6).
Figure 6 - Multisim Design Toolbox
- On the sbRIO-960X daughter card reference design#General page (Figure 7), you can see the introduction schematic for Single-Board RIO designs. This schematic shows a color coded view to each port on the analog/digital connectors.
Figure 7 - Multisim Schematic Guide
- On the sbRIO-960X daughter card reference design#DigitalOut page (Figure 8), you can see the circuitry that interfaces from the digital output ports to the daughter card (namely the LEDs).
Figure 8 - HCT595 LED Counter Circuit
- On the sbRIO-960X daughter card reference design#DigitalIn page (Figure 9), you can see the circuitry that interfaces to the digital input ports from the daughter card.
Figure 9 - Digital Input Ports
- On the sbRIO-960X daughter card reference design#Unused page (Figure 10), you can see the unused ports from this digital design.
Figure 10 - Unused Analog Ports
These simple schematics define the complete reference design. With a complete design, we simply need to take a look at our completed PCB layout.
Reference Design Layout
As mentioned previously the schematic is but one half of a complete design. There is also the layout for us to consider.
To open the layout file:
- Open Multisim (Start > All Programs > National Instruments > Circuit Design Suite 10.1 > Ultiboard 10.1)
- Select File > Open
- Browse to the sbRIO-960X daughter card reference design.ewprj file.
This relatively simple design (Figure 11) has already routed the various signals from the digital I/O mating connectors on the SB-RIO 960x board to the LEDs. There are also appropriate connections to the screw terminals on the outside edge of the board.
Figure 11 - Ultiboard Layout
To view the 3D properties of the board, we can use the 3D view in NI Ultiboard: Select Tools > View 3D.
The 3D representation of the board appears (Figure 12 and 13), and you can use your mouse to rotate the board 360 degrees in all directions. By using the rotation feature, you can see both the top side of the board with the LEDs and screw terminals, as well as the bottom side with the various connectors to mate with the Single-Board RIO design.
Figure 12 - Daughter Card Top View (3D)
Figure 13 - Daughter Card Bottom View (3D)
Reference Design Fabrication Files
For the design all of the various Gerber files that are needed have been generated, allowing you to very easily send your information to the board fabrication house for prototyping. These files are in the Gerber RS-274x standard (the industry standard), and provide PCB manufacturers with a layer-by-layer guide to the design and manufacture of your PCB.
We are now ready to begin exporting our completed file to our fabrication house, in this case Sunstone Circuits. We need to very simply:
- Select File > Export.
- The Export dialog box will appear.
- You have the ability to export to both industry standard formats (Gerber RS-274D and Gerber RS-274X). In this demonstration we will go for the preferred format for Sunstone and most fabrication houses – Gerber RS-274X.
- Select Gerber RS-274X in the dialog box (figure 14).
- Click on the Properties button
Figure 14 - Export Dialog Box
- You will now see the various layers and that can be exported to Gerber from the design (Figure 15).
- To select multiple layers at once, hold down the CTRL key on the keyboard while clicking the various layer names in the dialog box.
Figure 15 - Gerber File Export
- Select Board Outlines, Copper Bottom, Copper Inner 1, Copper Inner 2, Copper Top, Silkscreen Top, Silkscreen Bottom, Solder Mask Bottom, Solder Mask Top, and Drill.
- Click on the > arrow to the right of the “Available Layers” dialog.
- Click on the OK button.
- When you return to the Export dialog box you are ready to finally export your files.
- Click on the Export button.
- You will now iterate through the various layers of your board that you had previously selected to be exported into the Gerber format.
- Click on the OK button.
- Save the file to the appropriate location.
- Repeat the above process for all of the layers in your design.
- You are now ready to export the NC Drill file. Again select File > Export.
- Select NC Drill in the Export dialog box.
- Click on the Export button. Save the file to the appropriate location.