How to do it...

The steps for this recipe are as follows:

1. Import the necessary libraries:

#include <string.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "cJSON.h"
#include "driver/gpio.h"
#include "esp_system.h"
#include "esp_log.h"
#include "esp_http_client.h"
#include "esp_https_ota.h"
#include "wifi_functions.h"

2. Set the firmware version, certificates, and buffer size:

#define FIRMWARE_VERSION 0.1
#define UPDATE_JSON_URL "https://microshak.com/esp32/firmware.json"

extern const char server_cert_pem_start[] asm("_binary_certs_pem_start");
extern const char server_cert_pem_end[] asm("_binary_certs_pem_end");

char rcv_buffer[200];

3. Create an HTTP event handler:

esp_err_t _http_event_handler(esp_http_client_event_t *evt) 
{    
  switch(evt->event_id) {
        case HTTP_EVENT_ERROR:
            break;
        case HTTP_EVENT_ON_CONNECTED:
          ...