Re: Continuous Pulse-Width Measurement

jawereq@xxxxxxxxxxx wrote: 
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 would guess that this application would be simple with a smallish FPGA.
You will be paying more, especially if you cannot be done with the micro.
Does the micro communicate with the outside? You can put async serial in
FPGA, but the effort nay not be worth it. What does the micro do?



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Relevant Pages

  • Re: Continuous Pulse-Width Measurement
    ... >to be able to buffer about 1000 16-bit width measurements in one shot. ... >to transfer the captured pulse-widths to RAM, but all the transfer cycles ... the current ASIC and micro cost about $7. ... If the total cycle time can be guaranteed to be at least ...
    (comp.arch.embedded)
  • Continuous Pulse-Width Measurement
    ... to be able to buffer about 1000 16-bit width measurements in one shot. ... 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 ... the current ASIC and micro cost about $7. ...
    (comp.arch.embedded)