ADVANCED DIGITAL DESIGNDESIGN EXERCISE I

Metastability Measurement and Analysis

What you get from us

• A working late transition detector• Implementation of [PS13 and PS15]• But without the case separation• Only one FIFO is present

• Python based PC software• Automates the measurement• Prints a CSV trace to standard out

Environment

• Altera Cyclone-IV FPGA• Design software: Quartus• Includes all necessary design tools

• PC software• Python program for collection of CSV traces• Analysis with program of choice (Excel, Python, MATLAB, ...)

Your Task (LTD Measurement)

• Implement the case separation from [PS13, PS15]• Measure two different clock duty cycles

• One where only the master can be seen• One where master and slave are present

• Record enough data point• Per resolution time• Resolution time range

Your Task (LTD MTBF)

• Analyze your measurements (MTBF vs. resolution time)• Calculate the different TAU values (master and slave, if

applicable) for all cases and simulation runs• Estimate T0 (if applicable) for all cases and simulation

runs• Plot each case in a separate plot and visualize the

above calculated parameters• Comparison plots of

• All cases in a single run• All runs for a single case

Your Task (LTD Distribution)

• Analyze your measurements (TBU distribution vs. resolution time)• Plot each case in a separate plot (rising, falling, …)• Use a box-whiskers plot• Compare the mean value (MTBU) with the standard

deviation and the smallest/largest measured value for each resolution time

• What are the implications on system reliabiltiy?

Your Task (Oscilloscope)

• Measure the output of a metastable flip flop using an oscilloscope

• Create a color-grade timing plot (using the oscilloscope) showing all measured traces• Use the large scope in the lab for color grading

• Adapters for the oscilloscope inputs will be in the lab

• Generate a histogram of all observed output delays

LTD Example Result

LTD Example Comparison

LTD Example Box Plot

LTD Example 3D Histogram

References

• PS13 - T. Polzer and A. Steininger - An Approach for Efficient Metastability Characterization of FPGAs through the Designer - 19th International Symposium on Asynchronous Circuits and Systems, 2013

• PS15 - T. Polzer and A. Steininger - Measuring the Distribution of Metastable Upsets over Time - Euromicro Conference on Digital System Design, 2015

ADVANCED DIGITAL DESIGNDESIGN EXERCISE I

Metastability Measurement and Analysis