ESP32 esp-idf Eclipse でサンプルプログラムの確認。

取り敢えず、サンプルのソースをそのまま掲載します。
xxxxxx を自分の環境に合わせ設定すれば、そのまま動作します。

Wi-Fi Driver 、ESP HTTP Client の説明などと、見比べてソースを追えば、理解が深まるのでは、

https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/wifi.html
この、 wifi.html を参考にすると、Wi-Fi 接続が出来て、DHCPサーバーから、IPが
貰えると、event_handler() の case SYSTEM_EVENT_STA_GOT_IP:
へ処理が来るみたいです。

ここで、xEventGroupSetBits(wifi_event_group, CONNECTED_BIT);
を実行して、FreeRTOSの別タスクへの通知を行っているみたいです。
そうすると、
http_get_task() の中の、
xEventGroupWaitBits(wifi_event_group, CONNECTED_BIT,false, true, portMAX_DELAY);
の所で Wait していた処理が抜けてそれ以降を実行する流れの様です。
ふむふむ。

https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/protocols/esp_http_client.html

後、
xTaskCreate(&http_get_task, "http_get_task", 4096, NULL, 5, NULL);
は、FreeRTOS が最初から導入されているので、http_get_task がタスクとして、登録されて、
起動されています。

FreeRTOSは、おんちゃんは、下記を参考にさせて貰いました。
http://www.picfun.com/RTOS/FreeRTOSframe.html

おんちゃんも、これから、 esp-idf の勉強です。

/* HTTP GET Example using plain POSIX sockets This example code is in the Public Domain (or CC0 licensed, at your option.) Unless required by applicable law or agreed to in writing, this software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. */ #include <string.h> #include "freertos/FreeRTOS.h" #include "freertos/task.h" #include "freertos/event_groups.h" #include "esp_system.h" #include "esp_wifi.h" #include "esp_event_loop.h" #include "esp_log.h" #include "nvs_flash.h" #include "lwip/err.h" #include "lwip/sockets.h" #include "lwip/sys.h" #include "lwip/netdb.h" #include "lwip/dns.h" /* The examples use simple WiFi configuration that you can set via 'make menuconfig'. If you'd rather not, just change the below entries to strings with the config you want - ie #define EXAMPLE_WIFI_SSID "mywifissid" */ //#define EXAMPLE_WIFI_SSID CONFIG_WIFI_SSID //#define EXAMPLE_WIFI_PASS CONFIG_WIFI_PASSWORD #define EXAMPLE_WIFI_SSID "xxxxxxx" #define EXAMPLE_WIFI_PASS "xxxxxx" /* FreeRTOS event group to signal when we are connected & ready to make a request */ static EventGroupHandle_t wifi_event_group; /* The event group allows multiple bits for each event, but we only care about one event - are we connected to the AP with an IP? */ const int CONNECTED_BIT = BIT0; /* Constants that aren't configurable in menuconfig */ #define WEB_SERVER "www.xxxxx.com" #define WEB_PORT 80 #define WEB_URL "http://www.xxxxx.com/" static const char *TAG = "examples"; static const char *REQUEST = "GET " WEB_URL " HTTP/1.0\r\n" "Host: "WEB_SERVER"\r\n" "User-Agent: esp-idf/1.0 esp32\r\n" "\r\n"; static esp_err_t event_handler(void *ctx, system_event_t *event) { switch(event->event_id) { case SYSTEM_EVENT_STA_START: esp_wifi_connect(); break; case SYSTEM_EVENT_STA_GOT_IP: xEventGroupSetBits(wifi_event_group, CONNECTED_BIT); break; case SYSTEM_EVENT_STA_DISCONNECTED: /* This is a workaround as ESP32 WiFi libs don't currently auto-reassociate. */ esp_wifi_connect(); xEventGroupClearBits(wifi_event_group, CONNECTED_BIT); break; default: break; } return ESP_OK; } static void initialise_wifi(void) { tcpip_adapter_init(); wifi_event_group = xEventGroupCreate(); ESP_ERROR_CHECK( esp_event_loop_init(event_handler, NULL) ); wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT(); ESP_ERROR_CHECK( esp_wifi_init(&cfg) ); ESP_ERROR_CHECK( esp_wifi_set_storage(WIFI_STORAGE_RAM) ); wifi_config_t wifi_config = { .sta = { .ssid = EXAMPLE_WIFI_SSID, .password = EXAMPLE_WIFI_PASS, }, }; ESP_LOGI(TAG, "Setting WiFi configuration SSID %s...", wifi_config.sta.ssid); ESP_ERROR_CHECK( esp_wifi_set_mode(WIFI_MODE_STA) ); ESP_ERROR_CHECK( esp_wifi_set_config(ESP_IF_WIFI_STA, &wifi_config) ); ESP_ERROR_CHECK( esp_wifi_start() ); } static void http_get_task(void *pvParameters) { const struct addrinfo hints = { .ai_family = AF_INET, .ai_socktype = SOCK_STREAM, }; struct addrinfo *res; struct in_addr *addr; int s, r; char recv_buf[64]; while(1) { /* Wait for the callback to set the CONNECTED_BIT in the event group. */ xEventGroupWaitBits(wifi_event_group, CONNECTED_BIT, false, true, portMAX_DELAY); ESP_LOGI(TAG, "Connected to AP"); int err = getaddrinfo(WEB_SERVER, "80", &hints, &res); if(err != 0 || res == NULL) { ESP_LOGE(TAG, "DNS lookup failed err=%d res=%p", err, res); vTaskDelay(1000 / portTICK_PERIOD_MS); continue; } /* Code to print the resolved IP. Note: inet_ntoa is non-reentrant, look at ipaddr_ntoa_r for "real" code */ addr = &((struct sockaddr_in *)res->ai_addr)->sin_addr; ESP_LOGI(TAG, "DNS lookup succeeded. IP=%s", inet_ntoa(*addr)); s = socket(res->ai_family, res->ai_socktype, 0); if(s < 0) { ESP_LOGE(TAG, "... Failed to allocate socket."); freeaddrinfo(res); vTaskDelay(1000 / portTICK_PERIOD_MS); continue; } ESP_LOGI(TAG, "... allocated socket"); if(connect(s, res->ai_addr, res->ai_addrlen) != 0) { ESP_LOGE(TAG, "... socket connect failed errno=%d", errno); close(s); freeaddrinfo(res); vTaskDelay(4000 / portTICK_PERIOD_MS); continue; } ESP_LOGI(TAG, "... connected"); freeaddrinfo(res); if (write(s, REQUEST, strlen(REQUEST)) < 0) { ESP_LOGE(TAG, "... socket send failed"); close(s); vTaskDelay(4000 / portTICK_PERIOD_MS); continue; } ESP_LOGI(TAG, "... socket send success"); struct timeval receiving_timeout; receiving_timeout.tv_sec = 5; receiving_timeout.tv_usec = 0; if (setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, &receiving_timeout, sizeof(receiving_timeout)) < 0) { ESP_LOGE(TAG, "... failed to set socket receiving timeout"); close(s); vTaskDelay(4000 / portTICK_PERIOD_MS); continue; } ESP_LOGI(TAG, "... set socket receiving timeout success"); /* Read HTTP response */ do { bzero(recv_buf, sizeof(recv_buf)); r = read(s, recv_buf, sizeof(recv_buf)-1); for(int i = 0; i < r; i++) { putchar(recv_buf[i]); } } while(r > 0); ESP_LOGI(TAG, "... done reading from socket. Last read return=%d errno=%d\r\n", r, errno); close(s); for(int countdown = 10; countdown >= 0; countdown--) { ESP_LOGI(TAG, "%d... ", countdown); vTaskDelay(1000 / portTICK_PERIOD_MS); } ESP_LOGI(TAG, "Starting again!"); } } void app_main() { ESP_ERROR_CHECK( nvs_flash_init() ); initialise_wifi(); xTaskCreate(&http_get_task, "http_get_task", 4096, NULL, 5, NULL); }