One of our project uses MCF52254 PTA2 pin as a PWM output to control the LCD back light, every time when powered up, there is a short pulse at the pin, this will cause a flicker of the back light. I probed the signals, I supposed the pulse is caused by internal pull up.
C1: Reset pin
C2: PTA2(PWM pin)
C3: Another PWM pin with lower pull down resistor
C4: 3.3V MCU supply
I checked the manual, it says the initial state of pull-up is disabled:
But another table in the manual says the initial state of the pull-up is enabled:
So, what is the exat state of the internal pull-up during power up? How can we disable the internal pull up?
Thanks and regards!