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Nanosecond resolution with external interrupt

PostPosted: Wed Jan 31, 2018 11:06 am
by centigradz
Hello everybody,

I'm studing ESP8266 specs and i haven't wrote a single line of code (yet). What i want to do is to capture the exact rising and falling time of a signal within 10-20 nanoseconds resolution. I have done different experiments with arduino uno and due, but as you know the processors on those boards are not fast enough for the job.
What i thought to do is to configure the interrupts on the ESP to capture the rising and falling edges and timestamp them with the systick (using the processor cycle count). So, i'm curious to know if its possible to reach the precise timing i need with the 160Mhz processor of the ESP-12E and if it's possible to configure the ESP to fire the interrupt without any delay?

Thanks in advance,
Bilhan.

Re: Nanosecond resolution with external interrupt

PostPosted: Fri Feb 02, 2018 6:33 am
by stephenhawking
What I need to do is to catch the correct rising and falling time of a flag inside 10-20 nanoseconds determination. I have done distinctive analyses with Arduino UNO and due, however, as you most likely are aware the processors on those sheets are not sufficiently quick for the activity.

Re: Nanosecond resolution with external interrupt

PostPosted: Mon Feb 05, 2018 1:42 pm
by centigradz
Bump

Re: Nanosecond resolution with external interrupt

PostPosted: Wed Feb 07, 2018 7:16 am
by btidey
Not feasible in my view to do this directly on an ESP8266. You are talking 2-3 CPU clocks even at 160MHz. The ESP8266 also has a slower internal IO bus and you have some uncertain latency into getting into an ISR if you were going that route.

You should explain a bit more on what you are trying to measure to see if there are other approaches.