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Voltage drop at input pin? signal being displayed

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jit_singh_tara

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hi friends ...

When i touch the microcontroller pin to an already running signal being displayed by oscilloscope, the voltage drops .i know its due to some loading effect ....please suggest solution.....
 

voltage drop?

put a pullup there.
 
voltage drop?

i am already using 10k pullupon collector of transistor where i am checking the signal.....
 

voltage drop?

I think your pin is not defined as input. Impedance is creating the problem.
 
voltage drop?

i have defined the pin as input in tris register......of microcontroller.i have to use this signal as interrupt but the voltage level drops as soon as i connect the pin to collector....
 

voltage drop?

you mean to say you have connected it on RB0,......first tell me your controller no. i'll check the datasheet
 
voltage drop?

have you done the settings for INTEDG, & other settings required that is INTCON(may be different for your controller)
 

Re: voltage drop?

yes i have done the setting for rising edge and enabled int0 interrupt also......

Added after 1 hours 1 minutes:

i sorted out the issue :i had earlier used a 10k pull up at collector of transistor.....which i changed to lower resistance 1k .now there is enough current to drive the pin of controller low.....
 

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