Use a PIC, it can count up to 50MHz by itself.

-----Original Message-----
From: Wagner Lipnharski <wagnerl@EARTHLINK.NET>
To: PICLIST@MITVMA.MIT.EDU <PICLIST@MITVMA.MIT.EDU>
Date: Saturday, February 27, 1999 1:50 AM
Subject: MultiStage Counter with Shift Out


>Hi, there is a friend that needs a special circuit to attach
>to a PIC, but I can't find a single chip solution for him.
>
>He needs a 2^8 bits counter, 8 stages, easy solution,
>but it needs to have a serial output, not parallel, so
>he could read the actual counter 8 bits using a 2 wire
>serial transfer.
>
>He can not use a microcontroller to count it because the
>signal high frequency involved, around 15MHz.
>
>In real this chip could be so dump and silly, with just
>8 jk flipflops, a 8 bits shift register, and a couple
>of gates, it could be built with only 6 pins:
>Ground, Vcc, Pulses In, Reset, SDA + SCLK (2 wire comm).
>A 7th pin could control counting in BCD or Binary, and
>just to be snob, the 8th pin would be a bold "NC", or
>then, used to signal zero count (carry bit).
>
>A solution like that could use 8, 12, 16, 24 flipflops,
>so a high speed counting could be easily read by a PIC
>simply issuing RESET up/down, wait time for counting,
>reset up to hold count and enable serial transfer,
>and them issuing SCLKs to receive SDA data bits, then
>reset down to clear counter and repeat again.
>
>Does anybody knows anything like that available?  It is
>incredible that I can't find anything so silly like that.
>
>--------------------------------------------------------
>Wagner Lipnharski - UST Research Inc. - Orlando, Florida
>Forum and microcontroller web site:   http:/www.ustr.net
>Microcontrollers Survey:  http://www.ustr.net/tellme.htm