Project 12 - Poor Man's Oscilloscope (USB)

Sponsor/Mentor: School of EECS/Don Heer

44X Senior project

1 Project Overview
2 Background Research
3 System Requirements and Desired Features
4 Design Solutions
5 Top Level Block Design
5.1 Attenuation Circuit
5.2 Microcontroller Code
5.3 Microcontroller and ADC
5.4 FTDI Serial-to-USB IC
5.5 Software Front-end
5.6 Enclosure
5.7 PCB
6 Testing
7 Project Timeline
8 System Test Evidence
9 EXPO Materials

Project Members

Alex Edwards (edwardal@onid.NOSPAM.edu)
Mikael Stadden (staddenm@onid.NOSPAM.edu)
Kaviyaan Khalil (khalilk@onid.NOSPAM.edu)

Replace "NOSPAM" with "oregonstate"

Project Description

As the Electrical Engineering field gets more competitive, student labs are becoming more complex and hands on. The lab time students do have with access to proper instrumentation can be crowded due to increasing enrollment. These factors are requiring more work to be done outside of scheduled lab time for students. This can pose a problem when the necessary tools are only available in the lab setting. The goal of this project is to design and build a low budget USB-based oscilloscope for home use by OSU Electrical Engineers (and possibly others). The product would be intended for use as a debug and verification tool for student project work outside of a typical lab setting where more advanced tool are more sparse.

After discussing some ideas for our USB-Based Oscilloscope with each other, our mentor, and some university staff, we came up with a list of things we think our oscilloscope needs:

- It needs a wide voltage range. Depending on the project the student is working on, there may be a wide range of voltages to measure. Our goal is to be able to measure -50V to +50V to withstand a connection to any circuit an incoming freshman may try to analyze.

- It needs an attenuation setting. Since it would be impractical to have a very high resolution at such a high input voltage range, our USB oscilloscope needs to have a attenuation setting to be able to analyze small signals.

- It must be able to sample at 1Msps on 2 channels simultaneously. To be able to accurately represent higher frequency signals, we need to sample on a rate of at least 1Msps (Mega-sample per second) on two channels. Two channels will enable students to plot two waveforms at the same time, thus enabling them to do activities such as measure the input and output of an amplifier.

- It needs to be relatively cheap and easy to assemble. We would like the total cost of parts for each USB oscilloscope (once is large production) to be less than $100 making them affordable for students. It also needs to be easy to assemble and must have clear and concise directions.

- It needs to be able to calibrate oscilloscope probes. The student needs to be free to choose from a variety of probes, even those requiring calibration. Our USB-based oscilloscope needs to be able to calibrate student probes.

- It needs to have a trigger. The availability of a trigger is a necessity. We will provide the user with some basic triggering options such as triggering on falling, rising and high/low level events. We also may add triggering for certain protocols.

- It needs to have a USB interface. The most common interface today is USB, so we would like our oscilloscope to interface over USB to ensure compatibility. Depending on the requirements of our circuit components, we would like to make it USB powered.

- It needs to be compatible with multiple OS types. Since students use a variety of software on their computers, we would like multiple operating system support. Windows XP to Windows 7 and Linux support are immediate goals, with the possibility to support other operating systems as well.

- It needs to have a sufficient software package. Software will be a very important component in our design. The software component must be able to display measured waveforms in real time by transmitting a subset of sampled data to aid in debug work. If desired, the entirety of sampled data following a trigger event may be downloaded for further analysis. This will enable students to manipulate and display the data from the waveform in other applications (such as Microsoft Excel) for any work that may need to be compiled in a lab report.

Design

Finished Product Demo

References

This project is licensed under the Other/Multiple/Unlicensed