Gerhard Fiedler wrote: > Padu wrote: > >> I'm using CCP1 to measure the width of a pwm pulse generated by a RF >> receiver, the kind that is used in RC cars. The pwm is identical to the >> ones we use in RC servos. If I measure the signal amplitude, it goes >> from 0 to 4V, but as soon as I connect it to RC2, it drops to 0-2.9V >> range. Why is that? Will I have to use a voltage buffer to intervade the >> RF receiver and the CCP1 port? I'm using a PIC18F452. > > A buffer would only help if the problem is the max 1 uA that a PIC input > draws. > > I assume that RC2 is set to input (TRISC2=1), yes? :) And that nothing > else is connected to RC2? Correct > Does the voltage drop similarly if you connect a 3M or 4M resistor to the > receiver output? If not, connect Vdd through a 1k resistor to RC2 and > measure the voltage across the resistor. Should be less than 1 mV. The interesting point is that if I pullup RC2 with a 10K it (measuring the pwm) works. I'll perform the tests you suggested, but I was wondering what I'm trying to do is something pretty common no? How people usually connect a pwm source to be captured by the ccp module? Padu > > Gerhard > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist