test_servo.c

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/**
 * @file test_servo.c
 * Tests the servo outputs
 */

#include <px4_platform_common/time.h>
#include <px4_platform_common/px4_config.h>

#include <sys/types.h>

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <time.h>

#include <arch/board/board.h>
#include <drivers/drv_pwm_output.h>
#include <systemlib/err.h>

#include "tests_main.h"

int test_servo(int argc, char *argv[])
{
    int fd;
    int result = 0;
    servo_position_t data[PWM_OUTPUT_MAX_CHANNELS];
    servo_position_t pos;

    fd = open(PWM_OUTPUT0_DEVICE_PATH, O_RDWR);

    if (fd < 0) {
        printf("failed opening /dev/pwm_servo\n");
        goto out;
    }

    result = read(fd, &data, sizeof(data));

    if (result != sizeof(data)) {
        printf("failed bulk-reading channel values\n");
        goto out;
    }

    printf("Servo readback, pairs of values should match defaults\n");

    unsigned servo_count;
    result = ioctl(fd, PWM_SERVO_GET_COUNT, (unsigned long)&servo_count);

    if (result != OK) {
        warnx("PWM_SERVO_GET_COUNT");
        goto out;
    }

    for (unsigned i = 0; i < servo_count; i++) {
        result = ioctl(fd, PWM_SERVO_GET(i), (unsigned long)&pos);

        if (result < 0) {
            printf("failed reading channel %u\n", i);
            goto out;
        }

        printf("%u: %u %u\n", i, pos, data[i]);

    }

    /* tell safety that its ok to disable it with the switch */
    result = ioctl(fd, PWM_SERVO_SET_ARM_OK, 0);

    if (result != OK) {
        warnx("FAIL: PWM_SERVO_SET_ARM_OK");
        goto out;
    }

    /* tell output device that the system is armed (it will output values if safety is off) */
    result = ioctl(fd, PWM_SERVO_ARM, 0);

    if (result != OK) {
        warnx("FAIL: PWM_SERVO_ARM");
        goto out;
    }

    px4_usleep(5000000);
    printf("Advancing channel 0 to 1500\n");
    result = ioctl(fd, PWM_SERVO_SET(0), 1500);
    printf("Advancing channel 1 to 1800\n");
    result = ioctl(fd, PWM_SERVO_SET(1), 1800);
out:

    if (fd >= 0) {
        close(fd);
    }

    return result;
}