CMPE 100 Lab #5
Report due by midnight May 7

Description

Lab5 prelab

1. Read and understand the use of the oscilloscope from the following links:

   Note: We are not using a Tektronix scope in the lab, but almost all scopes have the same buttons and knobs.

   • http://www.tek.com/Measurement/App_Notes/XYZs/intro.htm
   • http://www.users.dircon.co.uk/~doctron/scope.htm

2. Submit answers to the following questions:
   1. Suppose I want to view a waveform of 5V peak to peak at 1 MHz. What would be a good setting for the Time/Div and V/div to view the waveform?
   2. What is the difference between CHOP and ALT?
   3. What is the x10 switch on the scope probe used for?
   4. What is the difference between AC and DC coupling?

Lab Work

Hardware/Software:

1. With the scope, measure the DC supply voltages (all 3) of the power rails on the protokit as accurately as you can.
2. Use the calibration output of the scope to determine the accuracy of the scope on your bench. Does your scope need adjustment?
3. Use the scope to look at the waveform from the oscillator in the protokit. Is it a square-wave, a sine-wave, a non-symmetric pulse, or some other waveform? What is range of frequencies that you can generate? You may not be able to measure this on the scope for some of the lower frequencies.
   

4. Build the circuit shown in the figure and answer the following.
   1. What is the truth table for the circuit?
   2. What do you expect the circuit to do under dynamic conditions?
5. Now drive the circuit with the protokit oscillator and view the result on the scope.
   1. You should be using both channels of the scope, one for the input waveform and one for the output waveform. You should trigger off of the input channel.
   2. What is the dynamic response to the circuit when it is driven by the oscillator?
   3. Look at the signal at the output of the inverter with and without the capacitor connected to the inverter. What is the capacitor doing? Give an estimate of the equivalent resistance of the inverter when pulling up and when pulling down, based on what you see on the scope.
   4. What is the measured duration of the glitch in the output with the capacitor connected? Estimate the duration of the glitch without the capacitor (explain your assumptions and method for this estimate).
6. Model this circuit on the Xilinx software (without the capacitor) and compare the simulation to reality. You should choose the appropriate mode in the simulator to view the glitch.
7. Show the TA that you can use the oscilloscope by demonstrating the results of the above exercises. Also, show your lab notebook to the TA with the record of your measurements and observations.

Report

In an inudstrial setting, you would probably include in your lab notebook photographs (or printout from a digital scope) of the most important waveforms. Since we don't have scope cameras available for you, sketch the important waveforms in your lab notebook and indicate what measurements you made from them.

Submit your lab report as a postscript (or HTML) file by e-mailing it as an attachment to the TA of your lab section. Also, submit the prelab for next week's lab assignment.

Lab 6 prelab

1. Read and understand the use of a D/A converter, and look at the data sheet for the chip that we will use to understand the interface from the FPGA to the D/A. When you use the D/A converter you will tie pins 16 and 14 together. What does this do?
2. Figure out how to make a 12-bit phase oscillator which is modeled by the equations above. You can have the frequency be fewer than 12 bits (add to the lower-order bits of the phase).
3. Generate a 'top-level' block diagram showing all of the important functional blocks in your function generator. Your block diagram should include:
   • A register
   • An adder
   • Functional blocks (not logic gates) for each different output function
   • Logic for switching the output
   • The interface to the D/A chip

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