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Interrupt response time

Topic last updated 08 Mar 2010, by John Robbins. 0 replies
John Robbins
08 Mar 2010
Hi, I was hoping to use the mbed to measure the time delay between two pulse trains, running at a 5 usec repetition rate. The delays would be of the order of a few 10s of nanoseconds. I was hoping to use the first pulse to start the counter, the second to stop it. The code currently uses the InterruptIn class. Right now the interrupt handler simply turns on/off an IO port that I can monitor with a logic analyser. At the moment I am monitoring only one set of pulses. The interrupt service routine seems to take at least 90 us to recover, so, of course, I am losing a lot of pulses. Is this an artefact of the InterruptIn class? Can I expect better performance by writing the interrupt handler directly? Thanks for any help, John.