Serial arduino with cmucam4 shield

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1

Hi....
I'm student at Shiraz university of technology and working on autodeminer robots...
And have a problem with serial of Arduino due...

My problem is that I feel the serial connection between these two boards isn't established

  1. Can I use the serial TX0 and RX0 in due when the USB connected to my laptop??
    Because these pins are connected to the USB2TTL chip on arduino....

2)Should I connect the IOREF pin to the 3.3 v?? My cmucamera is working on 3.3 volts...

I note that the baud rate of cmucamera board is on 19200 by default and I adjust that...

Where my problem would be???