well, that's what i have read in my AT89C52 book... , but thanks for the note, i'l give it a try, maybe it can measure more than 500 Khz
here is what is written in the book:
"the maximum input frequency that can be accurately counted is the oscillator frequency divided by 24, for our 6 megahertz crystal, the calculation yields a maximum external frequency of 250 KiloHertz"
maybe you meant that i add a prescaler? in that case.. well yes, i guess my AT89C52 could measure up to 500 Mhz easily... but i am talkin about the direct frequency the uC can measure...