Test your projects… ….from your PC!. Today’s Presentation Background Problem Statement Objectives Milestones Technical Approach Future Work Achievements;

Test your projects…Test your projects…

…….from your PC!.from your PC!

Today’s PresentationToday’s Presentation

• Background• Problem Statement• Objectives• Milestones• Technical Approach• Future Work• Achievements; Conclusions• Questions

The PC Based Oscilloscope TeamThe PC Based Oscilloscope Team

Students:Todd M. Buelow, EE

Michael Jendrysik, CprE

Chris Justice, EE

Mike McClimans, EE

Brian J. Smith, EE

Advisor:Dr. David Carlson

Associate Professor of Electrical & Computer Engineering

BackgroundBackground

• High cost of Oscilloscopes makes them out of reach for many

• Simple, low-cost oscilloscope are handy for small electronics projects

• Useful to the typical college student and the electronic hobbyist

Problem StatementProblem Statement

• To research, design, develop, and test a device that will take voltage vs. time measurements, as an oscilloscope does, and output those results to a PC

• To present the digitized voltage measurements to the user in the form of a live waveform display via custom software

ObjectivesObjectives

• Basic oscilloscope functionality

• A self-contained module

• Nine pin serial port connector to interface with a PC

• BNC connections for scope probes

• Control done via software

MilestonesMilestones

• Design hardware layout• Develop companion software• Develop microcontroller firmware• Fabricate PCB• Assemble circuit• Test and debug the module and software

PC Based OscilloscopePC Based Oscilloscope

Basic Hardware Layout

Hardware Design OptionsHardware Design Options

• ISA Card

• USB Port

• Parallel Port

• Serial Port


• Microcontroller ADCSimple, but slow

• External ADCFaster, but more complex

• Software selectable gain controlConvenient, flexible, but considerable added

complexity


• Static GainSimple, but not as flexible

• Single ended inputSimple, no need for inverting supply, provides more precise

ADC readings, but impractical for real use

• Positive and negative inputFlexible input signals, necessary for some applications

requires inverting supply, less precise ADC readings potential noise

PCB Layout ConsiderationsPCB Layout Considerations

• PCB Design issues– Sensitive analog signals mixed with noisy digital

circuitry

– Small form-factor

– Development board (ease of debug)

– Donated board turn

PCB Layout ConsiderationsPCB Layout Considerations

• Good PCB layout implementation– Separate analog and digital circuitry– Path to isolated analog ground– Ground fill, ground plane– Power planes – Bypass, bypass, bypass– All surface mount components– 10 10 spacing rules– 4 layer board (Outer 2 layers are signal layers, inner two are

power and ground planes)

+

-

CHA+

+

-

CHB+

CHB-

CHA-

Data bus

Memory address

Da

ta

Serial Translator

9 pin Connector

Serial to /from host PCTest signal

generatorRegulated power outputs

Test output

CDJ 10/14/98

Probe hardware block diagramProbe hardware block diagramPC-Based oscilloscope

Instrumentation amplifiers

Analogto digitalconverter

Memory

Microcontroller

Power supply

External power supply (unregulated)

Digital Trigger

Address counter

Control

PC Based Oscilloscope FirmwarePC Based Oscilloscope Firmware

• Goal: sampling, storing, & data communication with host PC

• C or Assembly?

• Assembly chosen due to– Tremendous amount of freeware example code

– Free compilers/emulators

– C compilers are all third party and little source code


Three stages of development• First version

– Check for commands from host and tell the host when messages received correctly

– Set output pins to DC for 5 seconds after receiving a bad command

– Send out square waves on output pins otherwise

• Second Version– Basically a voltmeter– Samples every few seconds and sends to host

• Third version– All the bells & whistles (full speed sampling, triggering, data

buffering in memory)


Yes.

No. Keep filling.

No. Continue polling for

PC command.

No.

Yes.

No. Look for new command.

Yes. Send more.

Yes. Analyze

command.

Yes. Prepare for continuous

output.

No. Prepare for trigger mode.

Startup. Initialize Port & Data

Initialize Ports, Data

Look for host PC

PC comman

d present?

Send data to serial port.

Store Data from ADCs

Send data in memory out to serial port.

Store data.

Go to next memory address.

Is trigger condition

met?

Is there more data

in the memory?

Is memory full?Does PC

demand streaming

data?

Select Channel, read data from ADC.

Host PC SoftwareHost PC Software

• Software Development– Visual C++ 6– Microsoft Foundation Class (MFC)– Dialog based– Compatible with Microsoft Windows 95/98

• Software Features– Time/Voltage scaling– Individual channel control– Measurements, triggers– Adjustable ground– User friendly– Possessing the look and feel of real oscilloscope

Host PC SoftwareHost PC Software

• Software Operation

– Win32 file handles for serial operation• No device driver needed

– Trigger mode

– Streaming mode

– Receive data via serial port

Host PC Software ScreenshotHost PC Software Screenshot Setup triggers for data collection.

Sample data at a regular basis, or only when you want it.

Save settings between testing sessions.

Take measurements and cut & paste the results to a lab report.

Add or subtract 2 waveforms.

Modify the time scaling with ease.

Change Voltage scaling at the push of a button.

Future WorkFuture Work

• Software

• Firmware

• Hardware

• Additions:– More math functions (FFT, etc.)

– Matlab and Excel datalinks in software

• Marketing strategies

What We LearnedWhat We Learned

• Working together

• Communication among team members

• Goal setting and co-motivation

Any questions?Any questions?

Documents

Test your projects… ….from your PC!. Today’s Presentation Background Problem Statement Objectives Milestones Technical Approach Future Work Achievements;