disable mcu pins

[overmindx]

Hi, is there a way to disable/enable a pin in an mcu? How can I do this? Please help. Thanks in advance.

[SherpaDoug]

What do you mean by "disable"? You can make a pin an input. Then it won't try to drive anything. But even an input pin should not be allowed to float with nothing driving it as that may cause excess power consumption and noise. Generally unused pins are set as outputs.
_________________
The search for better is endless. Instead simply find very good and get the job done.

[overmindx]

hi.. thanks for the reply.. i have two pins C6 and C7 that i use to communicate serially with my pc.. what i want is to have a control to disable and enable these pins.. so basically, if they are disable, they wont be able to send and receive data from the pc.. how can i do this? please help..

[SherpaDoug]

This seems like an odd request... Normally if you don't want a PIC to send data you simply don't instruct it to send the data. Are you worried about some virus or malicious software leaking secure information?

Here are some quick ideas:
If you are using UART interrupts you could simply mask the UART interrupts.
You could put a software lock inside the UART interrupt handlers.
You could set the UART baud rate to something ridiculous.
You could frequently set the output pin high (Stop bit) to mangle any outgoing byte.

Tell us more about your application. What PIC are you using?
_________________
The search for better is endless. Instead simply find very good and get the job done.

[overmindx]

Hi, in my firmware, I placed printf statements for debugging purposes and to know exactly what the system is doing. What I want is have a way to disable these serial pins if my board is not connected to the PC. It's because I've noticed though not sure about this, that if you have a serial communication and nothing is connected in it, the continuous output of data such as the use of printf causes erratic behavior. So to be sure, I just want to disable these pins if it is not connected to a PC. I hope I made sense in what I just wrote. Please help.

[mbradley]

Short answer no.

However, this is a software issue, don't use them.

I too use alot of output during debugging, but I do a define, and on final compile, I comment it out.

[Ttelmah]

As a separate comment, sending serial, with nothing connected, won't cause a problem.
I'd be more suspicious that the input line is generating continuous or random receive data. Depending how your receive 'handling' is done, this could cause problems.

Best Wishes

[jecottrell]

Try disabling the INT_RDA when not needed. I think I've found that a floating RX pin and an enabled INT_RDA, can generate continuous interrupts that cause problems.

Or you can just add a pull-up.