Continuous Pulse-Width Measurement

Hi,

I'm wondering if anyone knows of a microcontroller or some cheap hardware
in combination with a micro that can be used to continuously measure and
buffer all of the high and low pulse-widths of a binary signal. I'd like
to be able to buffer about 1000 16-bit width measurements in one shot.

The catch is that the smallest pulse width measurable needs to be 700ns or
better (500ns would be nice). I've looked at using an input capture pin to
a 20MHz or faster auto-cleared timer in combination with a DMA controller
to transfer the captured pulse-widths to RAM, but all the transfer cycles
generally add up to well over 1 micro-second. The 20MHz timer gives
sufficient resolution, but the time to buffer the data is too long.

Right now, the company I work for accomplishes this exact feat using an
ASIC. Together, the current ASIC and micro cost about $7. Can the same be
done for less money, and possibly with a single chip?

I appreciate anyone's suggestions on this problem.

Thanks!
.

Relevant Pages

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    ... I'm wondering if anyone knows of a microcontroller or some cheap hardware in combination with a micro that can be used to continuously measure and buffer all of the high and low pulse-widths of a binary signal. ... I've looked at using an input capture pin to a 20MHz or faster auto-cleared timer in combination with a DMA controller to transfer the captured pulse-widths to RAM, but all the transfer cycles generally add up to well over 1 micro-second. ...
    (comp.arch.embedded)