Added static IP fragment

wifi/fragments/connect_with_static_ip.c

@@ -0,0 +1,65 @@
+/**
+ * A common task is to connect to an access point and hence be a
+ * WiFi station.  By default, when we connect to the access point we
+ * then perform DHCP client protocols to obtain an IP address.  This
+ * takes a few seconds (in my experience).  If we are in the middle of
+ * edit, compile, run, test - repeat cycles ... every few seconds of
+ * "pause" can add up to our workflow.  This fragment illustrates the use
+ * of a static IP address.  We continue to connect to the access point but
+ * now instead of using DHCP to be allocated an address, we tell the
+ * access point the address we want to use.  Obviously it can't already
+ * be in use and it has to be in the range of valid addresses.  If these
+ * are satisfied, we shave off a few seconds of pause time and work as we
+ * immediately have our IP address.
+ */
+#include <lwip/sockets.h>
+
+// The IP address that we want our device to have.
+#define DEVICE_IP          "192.168.5.2"
+
+// The Gateway address where we wish to send packets.
+// This will commonly be our access point.
+#define DEVICE_GW          "192.168.5.1"
+
+// The netmask specification.
+#define DEVICE_NETMASK     "255.255.255.0"
+
+// The identity of the access point to which we wish to connect.
+#define AP_TARGET_SSID     "RASPI3"
+
+// The password we need to supply to the access point for authorization.
+#define AP_TARGET_PASSWORD "password"
+
+esp_err_t event_handler(void *ctx, system_event_t *event)
+{
+    return ESP_OK;
+}
+
+
+// Code fragment here ...
+  nvs_flash_init();
+  tcpip_adapter_init();
+
+  tcpip_adapter_dhcpc_stop(TCPIP_ADAPTER_IF_STA); // Don't run a DHCP client
+  tcpip_adapter_ip_info_t ipInfo;
+
+  inet_pton(AF_INET, DEVICE_IP, &ipInfo.ip);
+  inet_pton(AF_INET, DEVICE_GW, &ipInfo.gw);
+  inet_pton(AF_INET, DEVICE_NETMASK, &ipInfo.netmask);
+  tcpip_adapter_set_ip_info(TCPIP_ADAPTER_IF_STA, &ipInfo);
+
+  ESP_ERROR_CHECK(esp_event_loop_init(wifiEventHandler, 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));
+  ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_STA));
+  wifi_config_t sta_config = {
+    .sta = {
+      .ssid      = AP_TARGET_SSID,
+      .password  = AP_TARGET_PASSWORD,
+      .bssid_set = 0
+    }
+  };
+  ESP_ERROR_CHECK(esp_wifi_set_config(WIFI_IF_STA, &sta_config));
+  ESP_ERROR_CHECK(esp_wifi_start());
+  ESP_ERROR_CHECK(esp_wifi_connect());