Hi Farooq,

Doing multiplexed displays with micro isn't a good idea, for,

1. you have to do tricky programing to keep the display bright and not flickering.

2. the micro has to be all the time busy displaying. Ok you can program an interrupt but still the micro won't be easily able to do frequency measuring for you. (at least I think so)

So either do what Steve told you or use 4094, total 4. How ?? find yourself.

have fun

Simon