As students complete their education in engineering and science it is critical for them to apply their knowledge into senior design projects that represent the complex systems they will work on as engineers. In this application note we will discuss the role that NI tools (NI Multisim and myRIO) play in providing a comprehensive approach to senior design projects. Included in this document are a student design flow, links to design information and an introduction to myRIO.
NI myRIO is an embedded hardware device designed specifically for students to enable the design of real, complex engineering systems in college and universities. Students use the NI LabVIEW graphical programming language to program a field-programmable-gate-array (FPGA) on the NI myRIO to perform controls, robotics and mechatronics tasks. In many projects, NI myRIO represents just one part of a complete system with a need for analog circuitry to either signal condition, or a physical plant on which the algorithm acts. The various accessories connect to NI myRIO in the following ports:
In developing these complete systems, NI Multisim plays an integral role, providing students the ability to design circuitry and physically prototype custom interfaces extending the I/O capabilities in creating an integrated solution.
With Multisim students can characterize circuit behavior ahead of laboratory time. The design can then be translated to NI Ultiboard to rapidly develop a first printed circuit board (PCB) mini-system.
This tutorial uses examples to illustrate the capabilities of using NI myRIO and Multisim to provide students a complete solution for engineering challenges.
To learn more about NI myRIO click here.
To learn more about Multisim click here.
Multisim includes key features that make it easier for students to design for NI myRIO. During the senior design process students are encountering PCB development for the first time, and as such there are major hurdles to successfully defining circuit behavior, placing connectors, defining layout and fabricating the various files needed for a physical PCB prototype.
To help students with this process Multisim includes 2 key features to speed time-to-prototype.
1. The Multisim library and community includes special symbols that represents the mating connectors to NI myRIO
2. Specially defined templates that contain the various landpatterns, connector placements and board outlines to help a student to be able to quickly place their circuit into a design.
Within Multisim students can place down the NI myRIO connectors illustrating how the circuit will be connected to the NI myRIO. To find and place the connectors:
Select Place » Component from the menu bar. This will open the component browser.
Choose the following parameters as displayed in figure 3.
Database: Master DatabaseGroup: NI_ComponentsFamily: myRIOComponent: myRIO_MXP
This provides access to the NI myRIO connector.
Figure 3 – NI myRIO Component Database
With the NI myRIO_MXP selected, click OK.
The NI myRIO connector is a multi-section component allowing the student to place the IO sections on the schematic they will be using. Select the sections that are planned to be use:
AI – Analog input channels AO – Analog output channels DIO – Digital input and output channels UART – Serial communication channels POWER – Power supply channels
Note – The NI myRIO has two MXP connectors so up to two of these multi-section components can be placed on a schematic for use with a single NI myRIO.
Figure 4 shows the section selector pane and the sections placed on the schematic.
Figure 4 – Multi-section component for NI myRIO MXP connector
The NI myRIO also has a minisystem port (MSP) this is the same as used on the NI myDAQ so the students can use the NI myDAQ connector to gain access to this IO.
Database: Master DatabaseGroup: NI_ComponentsFamily: myDAQComponent: NI-myDAQ
The NI myDAQ connector component can be seen in Figure 5.
Figure 5 -Selection and placement of the myDAQ connector for using the minisystem (MSP) port on the NI myRIO
Templates for NI myRIO allow provide an inclusive Multisim schematic with the available inputs and outputs and an Ultiboard layout with the connectors and outline.
Multisim comes installed with the NI myRIO single MXP and dual MXP templates. The process for using these is outlined below:
Within Multisim select: File » New…
This opens the New Design window as seen in figure 6. Within this dialog select installed templates and we can select either the NI myRIO Dual MXP or the NI myRIO Single MXP. We also get a description and preview of the template design.
Figure 6 – Multisim new design window
Click Create and Multisim will open both the schematic and a Ultiboard layout which will form the template of our design. From here, in Multisim you can place the components you will be using and in Ultiboard you can create the layout of these components around the built in connector and outline. Figure 7 shows an image of the schematic and layout for the Multisim NI myRIO Single MXP template.
Figure 7 - The Multisim template for a Single MXP daughter board comprising of a Multisim schematic with the available IO and an Ultiboard layout with the connector and board outline.
The templates for the board-only NI myRIO are installed with Multisim. If using the enclosed NI myRIO the template is available on NI Labs details of which can be found at Multisim MXP Daughter-board Templates for myRIO.
Two templates are attached below and another template can be found at Multisim MXP Daughter-board Templates for myRIO.
Using Multisim schematic capture and simulation students can gain a comprehensive understanding of analog, digital and power theory. This theory will underlie the design of the project so a core understanding is essential. With virtual instruments designed to match those from the lab and the built in SPICE analysis models students can obtain a comprehensive understand of their circuit behavior.
Here we can see an example of a student learning the theory behind creating a bandpass filter for a microphone. Multisim provides connectivity to external hardware and visualization of the circuit response. Students can use this to select the most suited components ahead of physically prototyping the design in the lab.
Figure 8 – Simulation of a bandpass filter for a microphone connecting to external hardware and using virtual instruments to measure the response.
The following resources provide examples on how students can learn theory using NI Multisim in classes such as introductory analog courses, digital logic and power classes.
Basics Analog Circuits
Digital Electronics Basics
Power Electronics Fundamentals
Visit ni.com/multisim/courseware for a full list of available courseware.
At this secondary stage students will take their schematic and translate this into a physical design on a breadboard to interface it to the NI myRIO Using the breadboard version of the circuits as well as NI myRIO students, can visualize the performance of the prototype with their NI myRIO algorithm and see how the circuitry (in this case a bandpass filter) will interact as a part of their overall design.
Recommended steps include:
a.) Design a schematic in Multisim with physical devices that can be purchased or used in the laboratory. Often when simulating students will use virtual versions of devices. During this stage the student must be able to convert those parts (for example an operational amplifier) with an orderable device.
b) Build the circuit on a breadboard and wire it as seen in the figure below. The wiring to the NI myRIO connector can be done either at the NI myRIO Expansion Port (MXP) connector or the miniSystem port (MSP) depending on the I/O required.
c) The NI myRIO Expansion Port (MXP) protoboard accessory provides an existing breadboard accessory that connects to the 34 pin MXP port as seen in Figure 10 to connect and visualize the performance of the design.
Figure 9 – A schematic of the breadboard design alongside the physical breadboard connected to the NI myRIO Expansion Port (MXP).
Figure 10 – The NI myRIO expansion board accessory allows easy prototyping of the circuit.
Using NI LabVIEW students will program custom software to acquire the data and analysis the response of their circuit.
For students who are new to breadboarding this task can be daunting. The following resources provide students with a guide on how to learn how to breadboard using Multisim and NI tools:
NI Multisim 3D Environment
An introduction to Breadboards – Community YouTube video
The natural progression for a student is to completing a complete printed circuit board (PCB). The student will have completed the schematic and will have used the breadboard to confirm performance of the analog design. Understanding how to complete a PCB design is not easy, as such there are a number of resources available to students including:
With these resources students have the basis for senior design of a custom PCB Mini-system to be attached to the NI myRIO.
It is at this time that user-definable templates in Multisim and Ultiboard can provide valuable time-saving and design enabling features. Templates are important because they:
Allow students to focus on their design without the need to design the connectors or the outline.
Provide students with a synchronous schematic and layout approach for designing minisystems for the NI myRIO.
NI myRIO connectors on the schematic allow students to make the best use of the IO available on the NI myRIO.
In the Ultiboard design, the templates provide students the board outline and connector placement ensuring the connection to the NI myRIO can be made.
Educators can create custom templates providing students a starting point for their design and ensuring this can be achieved within the constraints of a university course.
More details on the available templates can be found here.
Further details on the enclosed and board-only myRIO template can be found here.
To use these templates and design a NI myRIO project the student will:
(a) Open a new NI myRIO template using the process described above. Save both the Multisim schematic and the Ultiboard layout to a single file location.
(b) Create the schematic on the NI myRIO schematic layout. Using the NI myRIO schematic component you can create all the physical net for your circuit which will then be checked when you are creating your layout in Ultiboard.
Figure 11– NI myRIO schematic template with the NI myRIO connectors
(C) Once the components have been placed on the schematic and the connections made with the NI myRIO inputs and outputs the net list can be transferred to Ultiboard. To do this, select: Transfer » Froward annotate to Ultiboard as shown in Figure 12.
Figure 12 – Forward annotation of components to Ultiboard.
(d) You will then be asked to save the netlist to file, save this in the same directory as your Ultiboard layout template.
(e) This will import the components to the predefined layout. From this point you can arrange your components and create the PCB routings. More detail on this process can be found here. Figure 13 shows the filter circuit above after forward annotating and once routed.
Figure 13 – The Ultiboard layout using the Single MXP daughter board template
Ultiboard provides students an opportunity to gain valuable experience creating a PCB. The intuitive environment and auto placement features eases the creation.
In this tutorial we have seen an example of a simple analog baseband filter being evaluated and built into a Minisystem PCB. However the NI myRIO system alongside Multisim is a truly scalable platform for solving simple engineering challenges fast through right through to developing custom solutions for complex senior design projects.
Here we can see an example involving the evaluation, design and production of a three phase power inverter mini-system. This demonstrates a complex senior design, or masters level project for power electronics and shows the flexibility of using Multisim and NI myRIO.
Figure 14 – A three phase power inverted evaluated in Multisim with the layout created in Ultiboard.
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