Just to show this is not exactly related to syscalls() ( printf() ) between userspace / kernelspace: root@wgd:~/dl-i2c-test# ./read_zonein > test.txt root@wgd:~/dl-i2c-test# cat test.txt PWM1: 0 Z1IN: 1 PWM2: 0 Z2IN: 1 PWM3: 0 Z3IN: 1 PWM4: 0 Z4IN: 1 PWM5: 0 Z5IN: 1 PWM6: 0 Z6IN: 1
PWM1: 1 Z1IN: 1 PWM2: 1 Z2IN: 1 PWM3: 1 Z3IN: 1 PWM4: 1 Z4IN: 1 PWM5: 1 Z5IN: 1 PWM6: 1 Z6IN: 1 Perhaps the read()'s and write()'s are too much for the system to handle ? But this did not used to be the case. Used to be one could at least make 50-100 calls of this nature per second, before seeing any system slow down. The above is with a sleep value of 200ms, and we can see that the inputs have not caught up with the output in the second half of the test. On Sat, May 13, 2017 at 4:02 PM, William Hermans <[email protected]> wrote: > Something odd I'm just now noticing is that GPI on the beaglewbone seems > to have some lag. > > What I'm doing:We have a cape with 6 channels PWM, 6 pins input, and > several pins output. In order to test the PWM circuitry on our capes, I'm > configuring these pins as GPO's, and we have a test header that ties the > PWM pins to the input pins. All this is configured via an overlay file, and > it is all correct. Additionally, we have LEDs on each channel PWM on these > headers for visual inspection. The LEDs light up correctly when the PWM > pins( again configured as GPO's for the purpose of this test ) are high. > > However, when setting these pins high, then reading back the value from > the PWM pins, and input pins, The input pins lag behind a great deal. Code: > #include <unistd.h> > #include <sys/stat.h> > #include <fcntl.h> > #include <stdio.h> > #include <errno.h> > #include <stdlib.h> > > #define HIGH 1 > #define LOW 0 > > #define PWM1 2 > #define PWM2 3 > #define PWM3 50 > #define PWM4 22 > #define PWM5 51 > #define PWM6 23 > > #define Z1IN 44 > #define Z2IN 45 > #define Z3IN 46 > #define Z4IN 47 > #define Z5IN 48 > #define Z6IN 49 > > void set_pin(int pin_num, int value) > { > char gpio_path[40] = {0}; > char str_value[2] = {0}; > > sprintf(str_value, "%d", value); > sprintf(gpio_path, "/sys/class/gpio/gpio%d/value", pin_num); > > int fd = open(gpio_path, O_WRONLY); > if(fd == -1){ > perror(gpio_path); > exit(1); > } > > int nread = write(fd, str_value, 1); > if( nread < 0){ > perror("write()"); > exit(1); > } > > close(fd); > } > > int get_pin(int pin_num) > { > char gpio_path[40] = {0}; > char str_value[2] = {0}; > > sprintf(gpio_path, "/sys/class/gpio/gpio%d/value", pin_num); > > int fd = open(gpio_path, O_RDONLY); > if(fd == -1){ > perror(gpio_path); > exit(1); > } > > read(fd, str_value, sizeof(str_value - 1)); > > close(fd); > > return strtol(str_value, NULL, 10); > } > > int main() > { > > set_pin(PWM1, LOW); > set_pin(PWM2, LOW); > set_pin(PWM3, LOW); > set_pin(PWM4, LOW); > set_pin(PWM5, LOW); > set_pin(PWM6, LOW); > sleep(1); > printf("PWM1: %i Z1IN: %i \n", get_pin(PWM1), get_pin(Z1IN)); > printf("PWM2: %i Z2IN: %i \n", get_pin(PWM2), get_pin(Z2IN)); > printf("PWM3: %i Z3IN: %i \n", get_pin(PWM3), get_pin(Z3IN)); > printf("PWM4: %i Z4IN: %i \n", get_pin(PWM4), get_pin(Z4IN)); > printf("PWM5: %i Z5IN: %i \n", get_pin(PWM5), get_pin(Z5IN)); > printf("PWM6: %i Z6IN: %i \n", get_pin(PWM6), get_pin(Z6IN)); > > printf("\n"); > > /***********************************************************/ > set_pin(PWM1, HIGH); > set_pin(PWM2, HIGH); > set_pin(PWM3, HIGH); > set_pin(PWM4, HIGH); > set_pin(PWM5, HIGH); > set_pin(PWM6, HIGH); > sleep(1); > printf("PWM1: %i Z1IN: %i \n", get_pin(PWM1), get_pin(Z1IN)); > printf("PWM2: %i Z2IN: %i \n", get_pin(PWM2), get_pin(Z2IN)); > printf("PWM3: %i Z3IN: %i \n", get_pin(PWM3), get_pin(Z3IN)); > printf("PWM4: %i Z4IN: %i \n", get_pin(PWM4), get_pin(Z4IN)); > printf("PWM5: %i Z5IN: %i \n", get_pin(PWM5), get_pin(Z5IN)); > printf("PWM6: %i Z6IN: %i \n", get_pin(PWM6), get_pin(Z6IN)); > > return 0; > } > > As anyone can see, really simple straight forward code. The sleep shown in > the code is required at this value, and if lowered, the input pins will be > set correctly, but will read wrong. So here's the output as it stands. > > root@wgd:~/dl-i2c-test# nano read_zonein.c > root@wgd:~/dl-i2c-test# gcc -Wall -o read_zonein read_zonein.c > root@wgd:~/dl-i2c-test# ./read_zonein > PWM1: 0 Z1IN: 1 > PWM2: 0 Z2IN: 1 > PWM3: 0 Z3IN: 1 > PWM4: 0 Z4IN: 1 > PWM5: 0 Z5IN: 1 > PWM6: 0 Z6IN: 1 > > PWM1: 1 Z1IN: 0 > PWM2: 1 Z2IN: 0 > PWM3: 1 Z3IN: 0 > PWM4: 1 Z4IN: 0 > PWM5: 1 Z5IN: 0 > PWM6: 1 Z6IN: 0 > > But change the sleep() value to .5( 500 ms ) . . . > root@wgd:~/dl-i2c-test# nano read_zonein.c > root@wgd:~/dl-i2c-test# gcc -Wall -o read_zonein read_zonein.c > root@wgd:~/dl-i2c-test# ./read_zonein > PWM1: 0 Z1IN: 1 > PWM2: 0 Z2IN: 1 > PWM3: 0 Z3IN: 1 > PWM4: 0 Z4IN: 1 > PWM5: 0 Z5IN: 1 > PWM6: 0 Z6IN: 1 > > > *PWM1: 1 Z1IN: 1PWM2: 1 Z2IN: 1* > PWM3: 1 Z3IN: 0 > PWM4: 1 Z4IN: 0 > PWM5: 1 Z5IN: 0 > PWM6: 1 Z6IN: 0 > > Change the sleep value to .2(200 ms ), and the executed code gets all > kinds of squirely. e.g. very inconsistent. > > Does anyone know what's going on here ? > root@wgd:~/dl-i2c-test# uname -r > 4.4.55-ti-r94 > root@wgd:~/dl-i2c-test# free > total used free shared buffers cached > Mem: 499308 64736 434572 1456 5792 32348 > -/+ buffers/cache: 26596 472712 > Swap: 0 0 0 > root@wgd:~/dl-i2c-test# uptime > 15:57:39 up 2:33, 1 user, load average: *0.00, 0.01, 0.00* > root@wgd:~/dl-i2c-test# cat /etc/dogtag > BeagleBoard.org Debian Image 2017-04-02 > > Even for a non RT kernel this seems ridiculously slow > > -- > 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/5885cd25-64f8-4989-940a-35ba85365828%40googlegroups.com > <https://groups.google.com/d/msgid/beagleboard/5885cd25-64f8-4989-940a-35ba85365828%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. 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