I pretty much followed this guide for ADC setup http://processors.wiki.ti.com/index.php/Linux_Core_ADC_User's_Guide#Usage
On Tue, Sep 29, 2015 at 11:03 PM, William Hermans <[email protected]> wrote: > Well it might be you're running in continuous mode. That much I do not > know, but it could be difference in kernels ? I could not say. > > On Tue, Sep 29, 2015 at 11:00 PM, Rathin Dholakia < > [email protected]> wrote: > >> Hi, >> >> I tried running your code and I was successful and unsuccessful both!! :-) >> >> Success: I could compile code it compiled and when I put "time ./test" I >> gave me following output >> >> real 0m0.011s >> user 0m0.000s >> sys 0m0.008s >> >> unsuccessful: it didn't show any readings!! >> My guess is it has something to do with my kernel preemtion, isn't it? >> >> On Wednesday, September 30, 2015 at 11:18:20 AM UTC+5:30, William Hermans >> wrote: >>> >>> Oh, and that is using one shot mode. I did not think to use continuous. >>> BUt I really wanted to see how slow using open(), read(), and close() >>> really were. Because I had done a lot of reading on the subject, but never >>> actually used it( I always used mmap() ). >>> >>> On Tue, Sep 29, 2015 at 10:41 PM, William Hermans <[email protected]> >>> wrote: >>> >>>> So, I got bored, and decided to do some "screwing around". But took me >>>> a while because I had not used, or setup the ADC peripheral before, but . . >>>> . here is some quick and dirty code, using std API stuff - Which breaks all >>>> the rules I spoke of in my second post heh. But still pretty darned fast. >>>> I'd be happier if I could use mmap() directly on >>>> /sys/bus/iio/devices/iio:device0/in_voltage0_raw, but either I've been >>>> trying to use an improper mode of operation. Or mmap() on that file >>>> location is not supported. So, might be forced to use mmap() on /dev/mem . >>>> ..ug! >>>> >>>> #include <unistd.h> >>>>> #include <sys/stat.h> >>>>> #include <fcntl.h> >>>>> #include <stdio.h> >>>>> #include <errno.h> >>>>> #include <stdlib.h> >>>>> >>>>> void read_adc(int fd) >>>>> { >>>>> char adc[5] = {0}; >>>>> int len = read(fd, adc, sizeof(adc - 1)); >>>>> adc[len] ='\0'; >>>>> printf("%s ", adc); >>>>> } >>>>> >>>>> int main() >>>>> { >>>>> const char *fname = >>>>> "/sys/bus/iio/devices/iio:device0/in_voltage0_raw"; >>>>> int count = 0; >>>>> >>>>> while( count++ <= 1000){ >>>>> int fd = open(fname, O_CREAT | O_RDONLY); >>>>> if(fd == -1){ >>>>> printf("error: %s\n", strerror(errno)); >>>>> exit(1); >>>>> } >>>>> >>>>> if(count % 15 == 0 && count != 0) >>>>> printf("\n"); >>>>> >>>>> read_adc(fd); >>>>> >>>>> close(fd); >>>>> } >>>>> printf("\n"); >>>>> >>>>> return 0; >>>>> } >>>>> >>>> >>>> Output: >>>> debian@beaglebone:~$ time ./test >>>> 4016 4020 4007 4010 4008 4010 4005 4005 4013 4015 4015 4011 4008 4001 >>>> 4010 4006 4006 4011 4007 4011 4003 4009 4006 4005 3995 3999 4005 4000 >>>> 3997 >>>> 4008 4016 4009 3997 4008 4011 4013 4011 4012 4009 4006 3997 4007 4007 >>>> 3999 >>>> 4014 4014 4007 4015 4008 4011 4012 4012 4007 4013 4016 4017 4016 4016 >>>> 4013 >>>> 4006 4013 4015 4006 4013 4009 4003 4011 4011 4017 4015 4008 4005 3998 >>>> 4000 >>>> 4002 4011 4012 4010 4013 4009 4010 4010 4010 4010 4011 4008 4007 4007 >>>> 4007 >>>> 4013 3998 4006 4007 4003 3999 4009 4005 4013 4018 4019 4014 4012 4003 >>>> 4008 >>>> 4010 4017 3999 4002 4008 4008 4008 4004 4010 4008 3996 4002 4009 4014 >>>> 4011 >>>> 4012 4006 4007 4004 4000 4008 4008 4010 4008 4007 4006 4003 4007 4000 >>>> 4008 >>>> 4003 4010 4003 4006 4006 3996 4001 4003 4000 4002 3996 4007 4003 4011 >>>> 4013 >>>> 4012 4017 4013 4008 4002 4010 4005 4013 4016 4014 4012 4015 4013 4013 >>>> 4007 >>>> 4011 4008 4010 4014 4016 4016 4015 4018 4013 4016 4005 3997 4007 3998 >>>> 4007 >>>> 4002 4004 4009 4007 4010 4010 4001 4005 4008 4003 4010 4012 4013 4006 >>>> 3994 >>>> 4014 4006 4008 4009 4014 4015 4012 4012 4013 4010 4012 4014 4015 4020 >>>> 4017 >>>> 4017 4013 4010 4020 4014 4012 4010 4008 3997 4002 4001 4012 4010 4006 >>>> 4016 >>>> 4010 4004 4004 4004 4003 4004 4004 3999 4003 4007 4008 4006 4005 4006 >>>> 4007 >>>> 4013 4013 4011 4010 4010 4005 3996 4002 4008 4012 4012 4007 4006 4000 >>>> 3999 >>>> 4009 4005 4013 4010 4008 4012 4011 4015 4016 4017 4013 4009 4008 4007 >>>> 4006 >>>> 4015 4012 4010 4013 4011 4016 4012 4013 4012 4009 4007 3998 3995 3998 >>>> 4004 >>>> 4003 4011 4009 4001 3998 4007 4008 4001 4008 4008 4012 4013 4007 3998 >>>> 3999 >>>> 4015 4007 3997 4005 4009 4007 4002 4009 4015 4012 4007 4009 4013 4017 >>>> 4015 >>>> 4010 4005 4011 4017 4015 4010 4013 4012 4004 4008 4012 4010 4014 4015 >>>> 4013 >>>> 4016 4016 4016 4007 4009 4011 4010 4009 4010 4010 4004 4004 4002 4002 >>>> 4011 >>>> 4008 4007 4004 4010 4006 4008 4007 4005 4006 4008 4002 4009 4013 4011 >>>> 4006 >>>> 4010 4015 4014 4016 4018 4015 4017 4015 4015 4018 4016 4013 4011 4013 >>>> 4016 >>>> 4017 3998 4012 4006 4008 4014 4011 4003 4012 4018 4014 4012 4005 3994 >>>> 4000 >>>> 4004 4003 4007 4012 4012 4005 4005 4006 4008 4001 3999 4004 4000 4004 >>>> 4000 >>>> 4011 4010 4005 4002 4009 4007 4002 4013 4015 4020 4012 4011 4011 4002 >>>> 4011 >>>> 4008 4013 4009 4012 4006 4011 4009 4015 4013 4009 4003 4008 4003 4005 >>>> 4009 >>>> 4017 4001 4010 4012 4009 4009 4007 4010 4007 4006 4004 4003 4008 4008 >>>> 4003 >>>> 4012 4009 4007 4008 4005 4006 4000 3995 4000 4007 4006 4003 4004 4009 >>>> 4004 >>>> 4008 4020 4010 4009 4006 4008 4015 4018 4017 4011 4014 4013 4010 4009 >>>> 4012 >>>> 4011 4009 4016 4017 4016 4011 4005 4007 4012 4014 4014 4005 4004 3998 >>>> 4000 >>>> 4009 4009 4005 3996 4006 3999 4002 4009 4014 4011 4009 4008 4008 4012 >>>> 4013 >>>> 4003 4007 4010 4012 4012 4010 4010 4010 4014 4017 4016 4007 4020 4013 >>>> 4007 >>>> 4019 4015 4014 4016 4016 4016 4009 4004 4000 4009 4012 4010 4015 4015 >>>> 4015 >>>> 4016 4011 4013 4008 4012 4009 4007 4006 4005 4006 4012 4004 4011 4015 >>>> 4009 >>>> 4010 4014 4004 3998 4008 4010 4004 4003 4008 4013 4013 4009 4007 4004 >>>> 4009 >>>> 4014 4013 4016 4012 4010 4011 4013 4013 4013 4008 4017 4015 4015 4011 >>>> 4014 >>>> 4016 4007 4013 4014 4009 3999 4008 4003 4005 4009 4014 4007 4003 3993 >>>> 3999 >>>> 3999 4005 4013 4003 4011 4009 4011 4010 4006 4002 4006 3998 4001 4003 >>>> 4009 >>>> 4011 4011 4016 4013 4018 4013 4010 4003 4000 4006 4015 4011 4017 4017 >>>> 4016 >>>> 4010 4017 4017 4016 4012 4016 4015 4013 4012 4013 4009 4003 4010 4006 >>>> 4012 >>>> 4004 4013 4001 4000 4005 3997 4004 4008 4012 4008 4005 3996 4003 3999 >>>> 4006 >>>> 4016 4002 4000 4002 4008 4009 4006 3995 4005 4008 4013 4012 4012 4009 >>>> 4007 >>>> 4013 4006 4018 4012 4005 4016 4014 4012 4011 4007 4014 4016 4015 4014 >>>> 4013 >>>> 4005 4007 4013 4008 4009 4002 4012 4011 4015 4013 4012 4010 4004 4007 >>>> 4005 >>>> 4013 4008 4013 4014 4014 4004 4012 4012 4012 4007 4009 4006 4010 4013 >>>> 4014 >>>> 4015 4006 4008 4009 4007 4004 4011 4005 4009 4007 4020 4015 4012 4005 >>>> 4008 >>>> 4021 4018 4016 4013 4003 4015 4015 4019 4014 4013 4003 4007 4009 4014 >>>> 4015 >>>> 3999 4016 4007 4008 4004 4008 4011 4003 4011 4012 4009 4006 4009 4008 >>>> 4005 >>>> 4002 4005 4011 4008 4011 4009 4016 4014 4010 4012 4016 4015 4011 4010 >>>> 4009 >>>> 4010 4011 4019 4018 4015 4017 4010 4000 4009 4015 4017 4017 4013 4017 >>>> 4012 >>>> 4011 4016 4014 3999 4008 4006 4006 4011 4010 4001 4000 4008 3998 4007 >>>> 4013 >>>> 4008 4007 4011 4008 4011 4007 4013 4012 4014 4009 4006 4006 4007 4000 >>>> 4002 >>>> 4012 4011 4008 4010 4004 4015 4013 4015 4014 4006 4019 4012 4007 4016 >>>> 4016 >>>> 4005 4009 4011 4010 4010 4004 4013 4014 4015 4015 4016 4011 4014 4009 >>>> 4004 >>>> 4015 4013 4009 4011 4009 4009 4006 4008 4005 3995 4001 4007 4007 4008 >>>> 4008 >>>> 4008 4008 4004 4006 4011 4010 4002 4011 4013 4009 4003 4000 4006 4011 >>>> 4010 >>>> 4015 4020 4016 4017 4017 4016 4016 4015 4014 4013 4010 4012 4006 4002 >>>> 4000 >>>> 4017 4016 4013 4010 4013 4008 4011 4010 4006 4002 4007 4009 4010 4011 >>>> 4007 >>>> 4011 4012 4014 4003 4003 4012 4010 4014 4013 4010 4007 3994 4000 4006 >>>> 4002 >>>> 3999 4006 4004 4008 4011 4005 4005 4010 4008 4012 4014 4017 4015 4015 >>>> 4001 >>>> 4011 4006 4015 4017 4013 4015 4014 4018 4016 4012 4011 4009 4011 4014 >>>> 4015 >>>> 4008 4009 4009 4006 4011 4010 4008 4010 4005 4006 4005 4005 4009 4003 >>>> 4009 >>>> 4008 4010 4011 4010 4012 4007 4009 4007 4000 4004 4008 4008 4013 4016 >>>> 4017 >>>> 4019 4016 4021 4018 4018 4012 4009 4007 4015 4015 4012 4013 >>>> >>>> real 0m0.328s >>>> user 0m0.010s >>>> sys 0m0.250s >>>> >>>> >>>> That's actually not too bad for opening, and closing the file 1000 >>>> iterations, then using printf() to display the data to stdout. So, looks >>>> like 328ms for 1000 iterations on the same adc channel. >>>> >>>> debian@beaglebone:~$ uname -a >>>> Linux beaglebone 4.1.5-ti-rt-r10 #1 SMP PREEMPT RT Fri Aug 14 00:02:42 >>>> UTC 2015 armv7l GNU/Linux >>>> >>>> debian@beaglebone:~$ cat /etc/dogtag >>>> BeagleBoard.org Debian Image 2015-03-01 >>>> >>>> Meaning Wheezy 7.8, and systemd disabled - if the later maters at all. >>>> >>>> >>> -- >> 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]. >> 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]. For more options, visit https://groups.google.com/d/optout.
