Why my same encryption's trrace looks entirely different on CW305?

1

I am using CW305 as the target and instead of running encryption on 10MHz, I am running on 30 MHz. And i have setup adc clock as following:
scope.clock.adc_src = "extclk_x4"

At 30 MHz. for encrypting same plaintext with same key I see two different wave randomly appearing as following two images, sometimes i see first one and sometimes the other one. I guess there is something happening with the capture frequency/sampling rate. What is happening and how can i get a consistent trace? At 10Mhz, it shows a consistent trace

30MHz_1
30MHz_1800×600 78 KB

30MHz_2
30MHz_2800×600 25.8 KB

2

Unless you’re using Husky to capture, you’ve exceeded the maximum sampling frequency:

image
image1131×274 26.9 KB

The other thing that could cause problem is if you didn’t declare your clock to be 30 MHz in Vivado.

3

should i just declare the clock frequency in constraint file where the clock is defined or somewhere else?

4

It’s in the .xdc; these are the commands to adjust:

create_clock -period 10.000 -name tio_clkin -waveform {0.000 5.000} [get_nets tio_clkin]
create_clock -period 10.000 -name pll_clk1 -waveform {0.000 5.000} [get_nets pll_clk1]

So the default is actually 100 MHz, if that’s what you’re using that wouldn’t be the cause of your problems (assuming your design meets timing).

What could be the issue then?

  1. Your design doesn’t meet timing,
  2. Exceeding CW capture maximum sampling rate. Just change scope.clock.adc_src to extclk_x1 to see.
  3. Your design isn’t working as expected.