okay teensy 4.0 , ra8875 display , audio shield ..currently running off usb power the ra8875 is powered off vcc and gnd looks good ..also running metro at 250ms as the display was way to frantic .. the problem ..I have has noise during the sweep ...So I figured I had best isolate the power for the display on a seperate power supply ..fine no problem .So I though okay ..I can run the teensy 4.0 off usb power and power the ra8875 from a seperate power supply ...my external supply checks good .no issues ..however with the teensy on USB ..and the ra8875 on external power the display will not come uo ..if I re-connect the display power back to the teensy it runs ...a little stumped as to the behaviour ..Am I missing something with respect to power ? I though that perhaps the power supply took more time to stabilize so I dropped in a 5 second delay in setup no luck ....thoughts ?