Goal Planning: Reaching Your Destination – Part 4 – Detours and Milestones
Test your projects… ….from your PC!. Today’s Presentation Background Problem Statement...
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Transcript of Test your projects… ….from your PC!. Today’s Presentation Background Problem Statement...
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
Hardware Design OptionsHardware Design Options
• Microcontroller ADCSimple, but slow
• External ADCFaster, but more complex
• Software selectable gain controlConvenient, flexible, but considerable added
complexity
Hardware Design OptionsHardware Design Options
• 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
PC Based Oscilloscope FirmwarePC Based Oscilloscope Firmware
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)
PC Based Oscilloscope FirmwarePC Based Oscilloscope Firmware
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?