linux-embedded-examples/pwm/pwm.c
Sanchayan Maity 31ba3f4f2b Update PWM code to demo rotation
Tower Pro Micro Servo 9g SG90 was used for test.
2017-05-09 13:02:34 +05:30

80 lines
1.8 KiB
C

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <stdint.h>
#include <stdbool.h>
#include <libsoc_pwm.h>
/*
* libsoc PWM API Documentation: https://jackmitch.github.io/libsoc/c/pwm/
*/
#define SERVO_PERIOD 20000000
#define DMIN 150000
#define DMAX 2000000
#define STEP_SIZE 5
int main(void)
{
pwm* vf_pwm = NULL;
uint32_t ret = EXIT_SUCCESS;
uint32_t pwm_number = 0;
uint32_t pwm_chip_number = 0;
uint32_t count = 2;
uint32_t ms;
printf("Enter PWM chip number:\t");
scanf("%d", &pwm_chip_number);
printf("Enter PWM number:\t");
scanf("%d", &pwm_number);
vf_pwm = libsoc_pwm_request(pwm_chip_number, pwm_number, LS_GREEDY);
if (vf_pwm == NULL) {
perror("PWM request failed");
return EXIT_FAILURE;
}
/* As required for Tower Pro Micro Servo 9g SG90 */
ret = libsoc_pwm_set_period(vf_pwm, SERVO_PERIOD);
if (ret == EXIT_FAILURE) {
perror("PWM set period failed");
goto exit_failure;
}
ret = libsoc_pwm_set_enabled(vf_pwm, ENABLED);
if (ret == EXIT_FAILURE) {
perror("PWM enable failed");
goto exit_failure;
}
while (count > 0) {
for (ms = DMIN; ms <= DMAX;) {
ret = libsoc_pwm_set_duty_cycle(vf_pwm, ms);
if (ret == EXIT_FAILURE) {
perror("PWM set duty cycle failed");
goto exit_failure;
}
ms = ms + STEP_SIZE;
}
for (ms = DMAX; ms >= DMIN;) {
ret = libsoc_pwm_set_duty_cycle(vf_pwm, ms);
if (ret == EXIT_FAILURE) {
perror("PWM set duty cycle failed");
goto exit_failure;
}
ms = ms - STEP_SIZE;
}
count--;
}
printf("Disabling PWM\n");
ret = libsoc_pwm_set_enabled(vf_pwm, DISABLED);
if (ret == EXIT_FAILURE)
perror("PWM disable failed");
exit_failure:
libsoc_pwm_free(vf_pwm);
return ret;
}