pwm_cap.c

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#define _GNU_SOURCE 1
#include "stdio.h"
#include <termios.h>
#include <unistd.h>
#include <errno.h>
#include <sys/types.h>
#include "libpruio/pruio.h"
#include "libpruio/pruio_pins.h"
 
#define P_OUT P9_21
#define P_IN P9_42
 
int
isleep(unsigned int mseconds)
{
  fd_set set;
  struct timeval timeout;
 
  /* Initialize the file descriptor set. */
  FD_ZERO(&set);
  FD_SET(STDIN_FILENO, &set);
 
  /* Initialize the timeout data structure. */
  timeout.tv_sec = 0;
  timeout.tv_usec = mseconds * 1000;
 
  return TEMP_FAILURE_RETRY(select(FD_SETSIZE,
                                   &set, NULL, NULL,
                                   &timeout));
}
 
int main(int argc, char **argv)
{
  pruIo *Io = pruio_new(PRUIO_DEF_ACTIVE, 4, 0x98, 0); 
  do {
    if (Io->Errr) {
               printf("initialisation failed (%s)\n", Io->Errr); break;}
 
    if (pruio_cap_config(Io, P_IN, 2.)) { //         configure input pin
          printf("failed setting input @P_IN (%s)\n", Io->Errr); break;}
 
    float_t
        f1 //                         Variable for calculated frequency.
      , d1 //                        Variable for calculated duty cycle.
      , f0 = 31250 //                            The required frequency.
      , d0 = .5;   //                           The required duty cycle.
    if (pruio_pwm_setValue(Io, P_OUT, f0, d0)) {
        printf("failed setting output @P_OUT (%s)\n", Io->Errr); break;}
 
    //           pin config OK, transfer local settings to PRU and start
    if (pruio_config(Io, 1, 0x1FE, 0, 4)) {
                       printf("config failed (%s)\n", Io->Errr); break;}
 
    struct termios oldt, newt; //             make terminal non-blocking
    tcgetattr( STDIN_FILENO, &oldt );
    newt = oldt;
    newt.c_lflag &= ~( ICANON );
    newt.c_cc[VMIN] = 0;
    newt.c_cc[VTIME] = 1;
    tcsetattr( STDIN_FILENO, TCSANOW, &newt );
 
    while(1) { //                                       run endless loop
      if (1 == isleep(1)) {
        switch (getchar()) { //                       evaluate keystroke
          case '0' : d0 = 0.0; break;
          case '1' : d0 = 0.1; break;
          case '2' : d0 = 0.2; break;
          case '3' : d0 = 0.3; break;
          case '4' : d0 = 0.4; break;
          case '5' : d0 = 0.5; break;
          case '6' : d0 = 0.6; break;
          case '7' : d0 = 0.7; break;
          case '8' : d0 = 0.8; break;
          case '9' : d0 = 0.9; break;
          case ',' : d0 = 1.0; break;
          case '.' : d0 = 1.0; break;
          case 'm' : f0 = (f0 > 5.5     ? f0 - 5. : .5); break;
          case 'p' : f0 = (f0 < 999995. ? f0 + 5. : 1000000.); break;
          case '*' : f0 = (f0 < 500000. ? f0 * 2  : 1000000.); break;
          case '/' : f0 = (f0 > 1.      ? f0 / 2  : .5); break;
          case '+' : f0 = 1000000.; break;
          case '-' : f0 = .5; break;
          default: goto finish;
        };
        if (pruio_pwm_setValue(Io, P_OUT, f0, d0)) { //   set new output
           printf("failed setting PWM output (%s)\n", Io->Errr); break;}
 
        printf("\n--> Frequency: %10f , Duty: %10f\n", f0, d0); //  info
      }
 
      if (pruio_cap_Value(Io, P_IN, &f1, &d1)) { //    get current input
          printf("failed reading input @P_IN (%s)\n", Io->Errr); break;}
 
      printf("\r    Frequency: %10f , Duty: %10f     ", f1, d1); // info
      fflush(STDIN_FILENO);
    }
 
finish:
    tcsetattr( STDIN_FILENO, TCSANOW, &oldt ); //         reset terminal
 
    printf("\n");
  } while (0);
 
  pruio_destroy(Io);       /* destroy driver structure */
  return 0;
}