Luberth Dijkman wrote: > I would like to make a tachometer > all i can find on the web are examples of freq meters > > i would like to use: > pic16F84 > 7x 7sement led's (20 000RPM) > maybe an extra ic for each segment so that the multiplexing speed of leds is not > important and a brighter less flikkering display is the result > > would like to measure the time_between_pulses > and 60sec/time_between_pulses is RPM i would say > update display and do it again Hi Luberth! :o) Is this your first time on the Piclist? I have watched your plotter CNC page etc for a couple of years now, very nice pages. :o) The tachometer should be fairly easy with a PIC, but I suggest using the freq rather than period measuring as it has a lot of advantages. For a tacho you really don't want to display more than 2 times per second, or the display flickers and gets messy. So set the PIC to time for 0.5 second and just use an internal timer to count pulses. Then a simple multiply by 2 and display the data in RPS. The only use where it is better to measure period is when the revs are very low, like under 100rpm which is unlikely with an engine or a CNC spindle etc. :o) -Roman -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics