test_ppm_loopback.c

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/**
 * @file test_ppm_loopback.c
 * Tests the PWM outputs and PPM input
 */

#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 <arch/board/board.h>
#include <drivers/drv_pwm_output.h>
#include <drivers/drv_rc_input.h>
#include <uORB/topics/rc_channels.h>
#include <systemlib/err.h>

#include "tests_main.h"

#include <math.h>
#include <float.h>

int test_ppm_loopback(int argc, char *argv[])
{

    int _rc_sub = orb_subscribe(ORB_ID(input_rc));

    int servo_fd, result;
    servo_position_t pos;

    servo_fd = open(PWM_OUTPUT0_DEVICE_PATH, O_RDWR);

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

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

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

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

        (void)close(servo_fd);
        return ERROR;
    }

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

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

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

    }

    // /* tell safety that its ok to disable it with the switch */
    // result = ioctl(servo_fd, PWM_SERVO_SET_ARM_OK, 0);
    // if (result != OK)
    //  warnx("FAIL: PWM_SERVO_SET_ARM_OK");
    //  tell output device that the system is armed (it will output values if safety is off)
    // result = ioctl(servo_fd, PWM_SERVO_ARM, 0);
    // if (result != OK)
    //  warnx("FAIL: PWM_SERVO_ARM");

    int pwm_values[] = {1200, 1300, 1900, 1700, 1500, 1250, 1800, 1400};


    for (unsigned i = 0; (i < servo_count) && (i < sizeof(pwm_values) / sizeof(pwm_values[0])); i++) {
        result = ioctl(servo_fd, PWM_SERVO_SET(i), pwm_values[i]);

        if (result) {
            (void)close(servo_fd);
            return ERROR;

        } else {
            warnx("channel %d set to %d", i, pwm_values[i]);
        }
    }

    warnx("servo count: %d", servo_count);

    struct pwm_output_values pwm_out = {.values = {0}, .channel_count = 0};

    for (unsigned i = 0; (i < servo_count) && (i < sizeof(pwm_values) / sizeof(pwm_values[0])); i++) {
        pwm_out.values[i] = pwm_values[i];
        //warnx("channel %d: disarmed PWM: %d", i+1, pwm_values[i]);
        pwm_out.channel_count++;
    }

    result = ioctl(servo_fd, PWM_SERVO_SET_DISARMED_PWM, (long unsigned int)&pwm_out);

    /* give driver 10 ms to propagate */

    /* read low-level values from FMU or IO RC inputs (PPM, Spektrum, S.Bus) */
    struct input_rc_s rc_input;
    orb_copy(ORB_ID(input_rc), _rc_sub, &rc_input);
    px4_usleep(100000);

    /* open PPM input and expect values close to the output values */

    bool rc_updated;
    orb_check(_rc_sub, &rc_updated);

    if (rc_updated) {

        orb_copy(ORB_ID(input_rc), _rc_sub, &rc_input);

        // int ppm_fd = open(RC_INPUT_DEVICE_PATH, O_RDONLY);



        // struct input_rc_s rc;
        // result = read(ppm_fd, &rc, sizeof(rc));

        // if (result != sizeof(rc)) {
        //  warnx("Error reading RC output");
        //  (void)close(servo_fd);
        //  (void)close(ppm_fd);
        //  return ERROR;
        // }

        /* go and check values */
        for (unsigned i = 0; (i < servo_count) && (i < sizeof(pwm_values) / sizeof(pwm_values[0])); i++) {
            if (abs(rc_input.values[i] - pwm_values[i]) > 10) {
                warnx("comparison fail: RC: %d, expected: %d", rc_input.values[i], pwm_values[i]);
                (void)close(servo_fd);
                return ERROR;
            }
        }

    } else {
        warnx("failed reading RC input data");
        (void)close(servo_fd);
        return ERROR;
    }

    close(servo_fd);

    warnx("PPM LOOPBACK TEST PASSED SUCCESSFULLY!");

    return 0;
}