Use power source on CW308 to test GPIO

Embedded Security ChipWhisperer Hardware
1

Hi,
I’m using CW308 + CW-Lite and want to test the voltage setting is correct or not.
Take CW308 UFO - NewAE Hardware Product Documentation for reference,
I connect the VCC1.2 to FILT, connect FILT to VREF. About the jumper, J4 use the mode which means VREF Network set by VREF Pin from Victim Board (DEFAULT), J14 use the mode which means Filter input set by FILT Pin from Victim Board (DEFAULT).
I do the small test using print(scope.io.tio_states), the code is as the following:

scope.io.tio3 = "high_z" # async_InReq_o
scope.io.tio4 = "high_z" # test_done

Connect J5/GPIO4 to J11/FILT_HP and J5/GPIO3 to J11/FILT_LP, then

while(1):
    time.sleep(0.005)
    print(scope.io.tio_states)

The result should be (0,0,1,1), but why does it always print different results such as (0,0,0,1), (0,0,1,1), (0,0,0,0), or (0,0,1,0)? What could be the reason?
I have try change the jumper wire, or connect J5/GPIO3 or J5/GPIO4 to VCC1.2 directly. It still has the same issue. Did I misunderstand the document and do the wrong setting?

Thanks!

ZT

2

Are you trying to measure 1.2V signals using the GPIO pins? If so, CW IO pins are 3.3V only, you’ll need to use some sort of level shifter.

3

Yes, I’m trying to measure 1.2V signals using the GPIO pins.
In my test, my chip mounted on CW308T-GENERIC with IO voltage 3.3V and core voltage is 0.9V. I’m confused about the connection with VREF. What is VREF pin need to connect with? 3.3V or 0.9V?
Thanks!
ZT

4

VREF should always be connected to the IO voltage, so 3.3V.

5

Hi,
Okay! Thanks!
ZT

6

Hi,
Sorry, I realized that I had been mistaken about my I/O voltage. If my I/O voltage is 2.5V, should the VREF be connected to the level-shifted 3.3V or the original 2.5V?Thank you for your assistance.
ZT

7

So long as it doesn’t do anything weird to your target, either should be fine. That pin is effectively NC on the capture side of things and it’s only used as a pullup on the nRST line on the CW308.

Alex

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