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GPIO PWM low voltage not at ground

Question asked by Frederick Soo on Aug 16, 2017
Latest reply on Aug 17, 2017 by Frederick Soo



I'm using PWM to drive a circuit off of PTD16 and am observing a low voltage of 440mV, instead of 0V (GND) as I might expect.  The high voltage is 5V.  This happens for 0% through 100% duty cycle.


I am using pin PTD16 (connected to the GREEN_LED feature on the S32K144 development board).  It doesn't seem to matter if I put a pull down resistor (internal or external) in place.  There is no documentation on what the GPIO low voltage out should be.  


Is this known behavior?  If so is there a way to reference to GND instead of 440mV?  Does it depend on which pin or drive strength is being used? My application needs PWM that can go from 0V to 5V.