timer1 counter with inductive proximity sensor npn no

Hi all,
this is my first forum question… I have to build a computer that will:

  • count low pulses ( from inductive proximity sensor npn no ) from 0 to 400Hz
  • register pushbutton event on hardware interrupt
  • send some info via serial port

the thing is that I’m afraid that if I will count low impulses with interrupts, those will cause problems with serial communication when impulses will be about 350-400Hz.

I’ve read somewhere that it is possible to connect external clock to timer1 and use this timer as a counter. Is it possible to connect this npn no sensor as external clock signal?

thanks in advance!

1. the serial communication on pin 0 and pin 1 is done by a dedicated circuit... but u should keep ur interrupt handler as short as possible... e. g. just incrementing a counter or so...

2. u could convert the frequency into a voltage and read that voltage with the ADC? or what is a "sensor npn no"? do u have a datasheet online?