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Let me preface this by saying I have searched and have yet to come up with a concrete answer. That being said, if one exists, please do not flame, I would still greatly appreciate being pointed in the right direction.

I have a 5270 and I am having it run a continuity check on my implementation. Basically, it switches off all current that runs through the circuit being tested and couples one GPIO pin on side A of the circuit and another GPIO pin on side B. The pin on side A is set to High (1) and side B takes a reading. If it reads current, the circuit is complete and the program makes note that the circuit is complete. If it does not read the current, the program makes note that the circuit is broken. However, I have tested all of the switching mechanisms to attach the GPIO pins to each side of the circuit and everything checks out but I still dont get a complete circuit confirmation from the program. Now because the circuit is more than just a jumper wire, there is probably some resistance on the circuit being tested and thus the current of the GPIO pin on side A might be reduced enough that the pin on side B is not "confident" that it is reading the proper signal.

Now that the background is done, the question. Can anyone tell me the minimum ratings (voltage and current) a GPIO pin must read in order to read "high?" This way I can check and see if there is too much resistance on the circuit I am testing. If there is not too much resistance, it must be something in my programming. If there is too much resistance, I will develop a supplementary circuit to replace the pin at side A with a synthetic current that will still meet the minimum ratings for GPIO read at side B.

Again, if this is already in NB's literature someplace, I apologize for posting this but I would still really appreciate if someone could point me in the right direction.

See MCF5271EC, Hardware Ref., table 7.3 for electrical characteristics. See MCF5271RM, Ref. Manual sec. 12.3.1.7 for drive strength control.

Anyway a simple pin-pin connection wouldn't have loading or Vio problems. One thing caught me was the 5270, 71, 82... have seperate registers for output and input. Reading the output register won't tell you the input state (5272 and most other uC's use the same reg. for I/O). All GPIO register programming info in sec 12 or RM

MasterFrmMO88, I hope you'll find that very little flaming (if any) goes on in this forum. We reserve our ire for spammers. While often answers are given that are just links to the Wiki or docs those are not to be taken as anything other than a helpful gesture. It's particular easy to overlook the FAQ on the wiki (not that your answer is there, I just want to make sure you know about it).

We've all been through the learning process and there many examples, manuals and other sources for information. We always appreciate people that take time to at least read the getting started docs but everyone I am familiar with here, is willing to save you time and give directions to help you be efficient. Don't hesitate to ask. Just don't try to sell us things to fix our health or golf games.