Here is my new Frequency meter who was done with a LCD's cellular phone!!! This is a simple project. The Frequency is passing through an op-amp to convert it in a square wave. The ouput of the op-amp is feeding the 3*8 bits counter (24 bits) who can accumulate at a maximum of 16777216 count.
The maximum frequency you can measure without changing the time base of one second is 16.777216 Mhz. The ATMega8 have 3 functions: enable the counter gate at each second, read his value and display it on the LCD.
Features
Small box
Frequency and period display
Auto Scale