hi, In oscilloscope, they use High speed ADC (1Gs/s) & FPGA for buffering .. Linux UI interacts with FPGA.. ADC->FPGA->CPU
Varghese On Mon, Oct 24, 2016 at 11:23 AM, varghese a <[email protected]> wrote: > Hi , > > I think , there is no direct substitute to pulseIn() > > you can catch the timing using two methods > > 1. Polling -> under Linux application environment "mmap()" the GPIO > Registers ,Set the MUX register to input mode & start polling the Input > status . > > 2. Interrupt -> under linux , mmap the gpio registers , Enable > Falling/edge detect interrupt ( refer the datasheet for base address), > subscribe to that interrupt number "request_irg()".. Caclulate the time > difference between 2 low/high interrupts.. use clock_gettime() > > Note : Polling method eats your CPU Cycles.. > > Under any OS environment ,1ms latency is guaranteed, so you might not be > able to get the exact timing if the pulse width is less than 1ms/1khz .. > (exception is hardware based time stamping) > > So if you want the exact value , you have to use baremetal coding .. but > no QT :) > > varghese. > > On Mon, Oct 24, 2016 at 2:01 AM, Arthur Caio <[email protected]> wrote: > >> Hey everyone, >> >> I have a project with a LM555 timer and need to calculate how much time >> it takes for an input to go from LOW to HIGH and then to LOW again. >> >> Basically, I want to know the period of a square wave generated by the >> LM555 timer. >> >> I did it with Arduino using the function Pulseln. But I need to do this >> using a Beaglebone and programming in C++ (Using QtCreator). >> >> Is there a way to "open" the function PulseIn so I know what it does? >> Moreover, do you guys have any piece of code that might help me? >> >> Thank you in advance. >> >> -- >> For more options, visit http://beagleboard.org/discuss >> --- >> You received this message because you are subscribed to the Google Groups >> "BeagleBoard" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To view this discussion on the web visit https://groups.google.com/d/ms >> gid/beagleboard/f8178e6f-1d26-4f00-9c5a-33bfdfe55ad0%40googlegroups.com >> <https://groups.google.com/d/msgid/beagleboard/f8178e6f-1d26-4f00-9c5a-33bfdfe55ad0%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> For more options, visit https://groups.google.com/d/optout. >> > > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CACk2RsQaH-Tb%2BF9pnJ5BY2LwTGwMg-Y7emuVQk31W9VMA%2ByZWw%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
