this is my connection

On porta.0 = clock of 74hc574
On porta.1 = clock of 74hc574
On porta.2 = clock of 74hc574
On porta.3 = cts
On porta.4 = serialin
On porta.5 = serialout

I use three 74hc574
portb.0-7 = pin2 -pin8 of 74hc574
portc.0-7 = pin2 - pin8 of 74hc574