fix(esp_modem): Update ap2ppp example to recover network on disconnection

Closes https://github.com/espressif/esp-protocols/issues/44

components/esp_modem/examples/ap_to_pppos/main/ap_to_pppos.c

@@ -124,6 +124,38 @@ void wifi_init_softap(void)
              EXAMPLE_ESP_WIFI_SSID, EXAMPLE_ESP_WIFI_PASS, EXAMPLE_ESP_WIFI_CHANNEL);
 }
 
+void start_network(void)
+{
+    EventBits_t bits = 0;
+    while ((bits & CONNECT_BIT) == 0) {
+        if (!modem_check_sync()) {
+            ESP_LOGE(TAG, "Modem does not respond, maybe in DATA mode? ...exiting network mode");
+            modem_stop_network();
+            if (!modem_check_sync()) {
+                ESP_LOGE(TAG, "Modem does not respond to AT ...restarting");
+                modem_reset();
+                ESP_LOGI(TAG, "Restarted");
+            }
+            continue;
+        }
+        if (!modem_check_signal()) {
+            ESP_LOGI(TAG, "Poor signal ...will check after 5s");
+            vTaskDelay(pdMS_TO_TICKS(5000));
+            continue;
+        }
+        if (!modem_start_network()) {
+            ESP_LOGE(TAG, "Modem could not enter network mode ...will retry after 10s");
+            vTaskDelay(pdMS_TO_TICKS(10000));
+            continue;
+        }
+        bits = xEventGroupWaitBits(event_group, (DISCONNECT_BIT | CONNECT_BIT), pdTRUE, pdFALSE, pdMS_TO_TICKS(30000));
+        if (bits & DISCONNECT_BIT) {
+            ESP_LOGE(TAG, "Modem got disconnected ...retrying");
+            modem_stop_network();
+        }
+    }
+}
+
 void app_main(void)
 {
     // Initialize NVS
@@ -149,16 +181,7 @@ void app_main(void)
     ESP_ERROR_CHECK(esp_event_handler_register(IP_EVENT, ESP_EVENT_ANY_ID, on_ip_event, NULL));
 
     // Start the PPP network and wait for connection
-    modem_start_network();
-    EventBits_t bits;
-    do {
-        bits = xEventGroupWaitBits(event_group, (CONNECT_BIT | DISCONNECT_BIT), pdTRUE, pdFALSE, portMAX_DELAY);
-        if (bits & DISCONNECT_BIT) {
-            ESP_LOGW(TAG, "Modem got disconnected from the PPP server: retrying...");
-            modem_stop_network();
-            modem_start_network();
-        }
-    } while ((bits & CONNECT_BIT) == 0);
+    start_network();
 
     // Initialize the AP and setup the NAT
     esp_netif_t *ap_netif = esp_netif_create_default_wifi_ap();
@@ -172,11 +195,10 @@ void app_main(void)
 
     // Provide a recovery if disconnection of some kind registered
     while (true) {
-        bits = xEventGroupWaitBits(event_group, DISCONNECT_BIT, pdTRUE, pdFALSE, portMAX_DELAY);
+        EventBits_t bits = xEventGroupWaitBits(event_group, DISCONNECT_BIT, pdTRUE, pdFALSE, portMAX_DELAY);
         if (bits & DISCONNECT_BIT) {
-            ESP_LOGW(TAG, "Modem got disconnected from the PPP server: restarting the network...");
             modem_stop_network();
-            modem_start_network();
+            start_network();
         }
     }
 }

components/esp_modem/examples/ap_to_pppos/main/network_dce.c

@@ -47,12 +47,31 @@ void modem_deinit_network(void)
     }
 }
 
-void modem_start_network()
+bool modem_start_network()
 {
-    esp_modem_set_mode(dce, ESP_MODEM_MODE_DATA);
+    return esp_modem_set_mode(dce, ESP_MODEM_MODE_DATA) == ESP_OK;
 }
 
-void modem_stop_network()
+bool modem_stop_network()
 {
-    esp_modem_set_mode(dce, ESP_MODEM_MODE_COMMAND);
+    return esp_modem_set_mode(dce, ESP_MODEM_MODE_COMMAND);
+}
+
+bool modem_check_sync()
+{
+    return esp_modem_sync(dce) == ESP_OK;
+}
+
+void modem_reset()
+{
+    esp_modem_reset(dce);
+}
+
+bool modem_check_signal()
+{
+    int rssi, ber;
+    if (esp_modem_get_signal_quality(dce, &rssi, &ber) == ESP_OK) {
+        return rssi != 99 && rssi > 5;
+    }
+    return false;
 }

components/esp_modem/examples/ap_to_pppos/main/network_dce.cpp

@@ -79,6 +79,24 @@ public:
         }
     }
 
+    bool sync()
+    {
+        return dce_commands::sync(dte.get()) == command_result::OK;
+    }
+
+    void reset()
+    {
+        dce_commands::reset(dte.get());
+    }
+
+    bool check_signal()
+    {
+        int rssi, ber;
+        if (dce_commands::get_signal_quality(dte.get(), rssi, ber) != command_result::OK)
+            return false;
+        return rssi != 99 && rssi > 5;
+    }
+
     [[maybe_unused]] bool init_sim(const std::string &pin)
     {
         // switch to command mode (in case we were in PPP mode)
@@ -166,14 +184,14 @@ extern "C" esp_err_t modem_init_network(esp_netif_t *netif)
     return ESP_OK;
 }
 
-extern "C" void modem_start_network()
+extern "C" bool modem_start_network()
 {
-    dce->set_mode(esp_modem::modem_mode::DATA_MODE);
+    return dce->set_mode(esp_modem::modem_mode::DATA_MODE);
 }
 
-extern "C" void modem_stop_network()
+extern "C" bool modem_stop_network()
 {
-    dce->set_mode(esp_modem::modem_mode::COMMAND_MODE);
+    return dce->set_mode(esp_modem::modem_mode::COMMAND_MODE);
 }
 
 extern "C" void modem_deinit_network()
@@ -182,4 +200,19 @@ extern "C" void modem_deinit_network()
     dce = nullptr;
 }
 
+extern "C" bool modem_check_sync()
+{
+    return dce->get_module()->sync();
+}
+
+extern "C" void modem_reset()
+{
+    dce->get_module()->reset();
+}
+
+extern "C" bool modem_check_signal()
+{
+    return dce->get_module()->check_signal();
+}
+
 }

components/esp_modem/examples/ap_to_pppos/main/network_dce.h

@@ -31,13 +31,18 @@ void modem_deinit_network();
 /**
  * @brief Starts the PPP network
  */
-void modem_start_network();
+bool modem_start_network();
 
 /**
  * @brief Stops the PPP network
  */
-void modem_stop_network();
+bool modem_stop_network();
 
+bool modem_check_sync();
+
+void modem_reset();
+
+bool modem_check_signal();
 
 #ifdef __cplusplus
 }

components/esp_modem/src/esp_modem_c_api.cpp

@@ -122,21 +122,16 @@ extern "C" esp_err_t esp_modem_set_mode(esp_modem_dce_t *dce_wrap, esp_modem_dce
         return ESP_ERR_INVALID_ARG;
     }
     if (mode == ESP_MODEM_MODE_DATA) {
-        dce_wrap->dce->set_data();
-    } else if (mode == ESP_MODEM_MODE_COMMAND) {
-        dce_wrap->dce->exit_data();
-    } else if (mode == ESP_MODEM_MODE_CMUX) {
-        if (dce_wrap->dce->set_mode(modem_mode::CMUX_MODE) &&
-            // automatically switch to data mode for the primary terminal
-            dce_wrap->dce->set_mode(modem_mode::DATA_MODE)) {
-            return ESP_OK;
+        return dce_wrap->dce->set_mode(modem_mode::DATA_MODE) ? ESP_OK : ESP_FAIL;
+    }
+    if (mode == ESP_MODEM_MODE_COMMAND) {
+       return dce_wrap->dce->set_mode(modem_mode::COMMAND_MODE) ? ESP_OK : ESP_FAIL;
+    }
+    if (mode == ESP_MODEM_MODE_CMUX) {
+        return dce_wrap->dce->set_mode(modem_mode::CMUX_MODE) ? ESP_OK : ESP_FAIL;
     }
-        return ESP_FAIL;
-    } else {
     return ESP_ERR_NOT_SUPPORTED;
 }
-    return ESP_OK;
-}
 
 extern "C" esp_err_t esp_modem_read_pin(esp_modem_dce_t *dce_wrap, bool *pin)
 {
@@ -393,3 +388,8 @@ extern "C" esp_err_t esp_modem_set_gnss_power_mode(esp_modem_dce_t *dce_wrap, in
     }
     return command_response_to_esp_err(dce_wrap->dce->set_gnss_power_mode(mode));
 }
+
+extern "C" esp_err_t esp_modem_reset(esp_modem_dce_t *dce_wrap)
+{
+    return command_response_to_esp_err(dce_wrap->dce->reset());
+}

components/esp_modem/test/target/main/NetworkDCE.cpp

@@ -87,7 +87,7 @@ esp_err_t modem_init_network(esp_netif_t *netif)
     return NetModule::init(netif);
 }
 
-void modem_start_network()
+esp_err_t modem_start_network()
 {
     NetModule::start();
 }