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→Automatically Resetting Target
If we are going to start with the target at a pre-determined state, we need to reset the target. There are two ways of automatically performing this. The method used here will use the existing programmer interface to reset the device by performing that "read signature" operation we have already been using. The other method is to toggle a GPIO pin, which is more generic for future use.
This was introduced in [[Tutorial_B3-1_Timing_Analysis_with_Power_for_Password_Bypass#Reset_via_Auxiliary_Module]].
To setup the automatic reset, perform the following:
<ol style="li> Scroll down the list-style-type: decimal;of scripts, and you'll find one labeled "aux_reset_cw1173.py". This script has a simple function of attempting to reset the XMEGA device using the programmer:<br>[[File:auxreset_test1.png|600px]]</li><pli>Switch Hit the "Run" button. If you switch to the ''General Settings'' "Auxilary Module" tab, and select you'll see it's been added to the appropriate "Auxiliary Module"list of modules at the specified location.:</pbr><ol style="list-style-type[[File: lower-alpha;"auxreset_test2.png|400px]]</li><li>For ChipWhisperer-Lite (CW1173/CW1180)Looking at the code of the script, select you can see how this script is using an external module "linking it to a specific auxilary module trigger:<syntaxhighlight lang=python>from chipwhisperer.capture.auxiliary.ResetCW1173Read import ResetCW1173 # GUI compatibilitytry: aux_list = self.aux_listexcept NameError: pass # Delay between arming and resetting, in msdelay_ms = 1000 # Reset AVR/XMEGA via CWdeviceResetter = ResetCW1173(xmega=True, delay_ms=delay_ms)# Reset AVR#Resetter = ResetCW1173(xmega=False, delay_ms=delay_ms) # Reset before arming -Lite"more stableaux_list.register(Resetter.resetThenDelay, "before_trace")# Reset after arming - scope can catch entire reset#aux_list.register(Resetter.delayThenReset, "after_arm")</lisyntaxhighlight><li>For ChipWhisperer-Capture Rev 2, select You can edit the values required such as reset time "Reset AVR via ISP-MKII"location by changing the script (using an external editor). But an easier method is to insert it into our attack script itself. As a test we'll see if the default values work. We will later integrate this into a full example script.</li></ol>
We can now confirm the reset works with the "Capture 1" button. This requires us to disable the normal routing of the output data to a file for analysis, as we want to just dump data to the terminal emulator. To do this:
