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MCF51JM128VLK releasing control of PTH2?

Question asked by Dave Knight on Oct 7, 2016
Latest reply on Oct 31, 2016 by Dave Knight

Is there an issue with PTH2, or with GPIO pins on the MCF51JM128VLK in general that causes the MCF51JM128VLK to release control of the pin and let it float high, or some similar behavior.


I'm using MCF51JM128VLK to drive LTC2862, to convert UART into RS485.


PTH2 sets the direction of the data flow.


PTH2 sometimes get stuck in logic 1. The pins it's driving(Driver Enable and Receiver Enable) aren't drawing excessive current. 


I've tried removing PTH2 from the circuit and using PTC7. PTC7 doesn't seem to get stuck like PTH2, but sometimes our device has to run a long time to get failure mode. I'd feel more comfortable moving forward if I knew the cause of the failure.