Need some creativity help...only 1 pin left

[bonedoc]

So, I have a single input pin left on my microchip. My code has 2 modes, depending on the input type to this pin. When the code starts, a 0V on the pin indicates one mode. Otherwise, it moves on to the other mode. In the second mode, the input is receives data that has a 5v resting state.

I need to figure out how to explicitly keep the data line low at start up while keeping the high data stream off. Any ideas?

I thought I could simply control the power to the data device with a npn mosfet, so there is no data stream until I turn it on. However, the input pin is sensing some voltage (or the pin is floating). I thought about a pull down, but since the data line is resting high and has a pull up resistor, isnt this an issue?

 

[jackorocko]

npn mosfet

@ 1 AM this made me laugh, now I can go to bed with a smile on my face. Thanks

 

[bonedoc]

Sorry....operating on no sleep....

I didnt mean to put mosfet on there. I meant npn transistor.

 

[KrisBlueNZ]

So you have a device that provides an idle-high data signal to the PIC and you want to be able to force the PIC's input low in some circumstances? You could insert a series resistor and put an NPN to pull the PIC pin firmly low. Of course if you have an AND gate available it's even easier. Why not post a schematic, or at least tell us what the "data device" is and more specifically what you want to do.