problem exploiting input signal

[nges]

hello, my ideas with microcontrollers are sometimes limited, please please i really need help.
i am trying to interface the pic16f877a with an input signal that is very very small (about 200mv). i am using an input sensor that sends one pulse of 200mv and goes back to 0v, but i know that the input voltage for digital inputs should be atleast 3v
someone should help me tell how i can exploit this low voltage or how i can even amplify the pulse before using it at the level of the microcontroller. pls

[Acetronics]

Hi,

you could try to use one ADC input ...
200 mV will show 40 as a result ( 80 @ best conditions ) , so it's worth the try ...

Alain

[jumper]

Hi,

Or you can try to use the built in comparators, either with an external reference voltage (resistor divider) or the comparator voltage reference module that will allow you to set different values to compare against. Then you can use the output or the interuptflag for your code later. This will give you a digital solution for a really weak signal level.

Look at chapter 12 and 13 in the newest datasheet for 877A and you can see how it can done.

[nges]

Thanks alot, i will try it out