You are right, we had the settings for VCC-IO set to 3.3V. However, now that we switched to VREF (that we route from 5V pin of Arduino), we are no longer able to program the Arduino from the CW-Lite (by using the command cw.program_target(scope, program, aes_hex_path)).
When trying to program it, we get the following error:
OSError: Verify failed at 0x0000, c != ff
Our connections are the following:
Arduino CW506 20-pin connector
Rx (0) 12 (Rx - IO1)
Tx (1) 10 (Tx - IO2)
TRG (A0) 16 (TRG - IO4)
5V 8 (VREF)
GND 2 (GND)
At the moment we are not connecting the Arduino clock (pin 8 on Arduino) to pin 11 (HS1) on CW506 as we saw that introduces a lot of noise and is not necessary for establishing the SimpleSerial protocol between the CW and Arduino. We want to get this protocol running first, and then proceed to capture the traces and perform an attack.