Servo Control for SG90 (0 to 180 degree) Example using esp-open-rtos

esp-open-rtos-servo-control.c

// Servo Control for SG90 (0 to 180 degree)
// MIT License Fonger

// Connect signal pin to NodeMCU D7 (GPIO13)
// add EXTRA_COMPONENTS = extras/pwm to makefile
#include <stdio.h>
#include <FreeRTOS.h>
#include <esp/uart.h>
#include <esp8266.h>
#include <task.h>
#include <pwm/pwm.h>

inline uint16_t get_servo_duty_cycle(double angle) {
  if (angle > 180) return -1;
  return (uint16_t)((0.025 + (0.12 - 0.025) * (angle / 180.0)) *
                    (double)UINT16_MAX);
}

void servo_task(void *arg) {
  uint8_t pins[1];
  printf("pwm_init(1, [13])\n");
  pins[0] = 13;  // D7 GPIO13
  pwm_init(1, pins, false);

  printf("pwm_set_freq(50)     # 50Hz\n");
  pwm_set_freq(50);
  pwm_start();
  while (true) {
    for (int i = 0; i <= 180; i++) {
      pwm_set_duty(get_servo_duty_cycle(i));
      vTaskDelay(10 / portTICK_PERIOD_MS);
    }
    vTaskDelay(1000 / portTICK_PERIOD_MS);
    for (int i = 180; i >= 0; i--) {
      pwm_set_duty(get_servo_duty_cycle(i));
      vTaskDelay(10 / portTICK_PERIOD_MS);
    }
  }
}

void user_init(void) {
  uart_set_baud(0, 115200);
  xTaskCreate(servo_task, "Servo Task", 4096, NULL, tskIDLE_PRIORITY, NULL);
}