using 4 encoder with arduino due

Hi

I'm using 4 rhino planetary gear motor with in built optical encoder of 2000 cpr. MDS40B cytron as motor driver. Arduino due with USB host shield 2.0 and a PS3 .
problem is that when i am using 3 encoder simultaneously , everything works fine but when i connect 4th encoder to arduino due the controls of the PS3 cease to function.

kicfdds.ino (9.11 KB)