fix(modem): Minor cleanup of pppos example

* Use CONFIG_EXAMPLE_DETECT_MODE_BEFORE_CONNECT to demonstrate mode
detect
* Use disconnection flag to indicate conneciton issue and gracefully
degrade to command mode
* Remove IDF-verion < v5.0 code

components/esp_modem/examples/pppos_client/main/Kconfig.projbuild

@@ -211,4 +211,13 @@ menu "Example Configuration"
             publishes another MQTT message.
             Connection to the MQTT broker should be kept.
 
+    config EXAMPLE_DETECT_MODE_BEFORE_CONNECT
+        bool "Detect mode before connect"
+        default n
+        help
+            Set this to true to demonstrate mode auto-detection.
+            If enabled, the example tries to recognize the actual mode.
+            If mode is detected correctly and it is not a command mode,
+            then the example switches to command mode.
+
 endmenu

components/esp_modem/examples/pppos_client/main/pppos_client_main.c

@@ -34,6 +34,7 @@
 static const char *TAG = "pppos_example";
 static EventGroupHandle_t event_group = NULL;
 static const int CONNECT_BIT = BIT0;
+static const int DISCONNECT_BIT = BIT1;
 static const int GOT_DATA_BIT = BIT2;
 static const int USB_DISCONNECTED_BIT = BIT3; // Used only with USB DTE but we define it unconditionally, to avoid too many #ifdefs in the code
 
@@ -55,6 +56,7 @@ static void usb_terminal_error_handler(esp_modem_terminal_error_t err)
 }
 #define CHECK_USB_DISCONNECTION(event_group) \
 if ((xEventGroupGetBits(event_group) & USB_DISCONNECTED_BIT) == USB_DISCONNECTED_BIT) { \
+    ESP_LOGE(TAG, "USB_DISCONNECTED_BIT destroying modem dce");                                            \
     esp_modem_destroy(dce); \
     continue; \
 }
@@ -140,6 +142,7 @@ static void on_ip_event(void *arg, esp_event_base_t event_base,
         ESP_LOGI(TAG, "GOT ip event!!!");
     } else if (event_id == IP_EVENT_PPP_LOST_IP) {
         ESP_LOGI(TAG, "Modem Disconnect from PPP Server");
+        xEventGroupSetBits(event_group, DISCONNECT_BIT);
     } else if (event_id == IP_EVENT_GOT_IP6) {
         ESP_LOGI(TAG, "GOT IPv6 event!");
 
@@ -158,6 +161,7 @@ void app_main(void)
     ESP_ERROR_CHECK(esp_event_handler_register(NETIF_PPP_STATUS, ESP_EVENT_ANY_ID, &on_ppp_changed, NULL));
 
     /* Configure the PPP netif */
+    esp_err_t err;
     esp_modem_dce_config_t dce_config = ESP_MODEM_DCE_DEFAULT_CONFIG(CONFIG_EXAMPLE_MODEM_PPP_APN);
     esp_netif_config_t netif_ppp_config = ESP_NETIF_DEFAULT_PPP();
     esp_netif_t *esp_netif = esp_netif_new(&netif_ppp_config);
@@ -177,7 +181,7 @@ void app_main(void)
     dte_config.uart_config.rx_buffer_size = CONFIG_EXAMPLE_MODEM_UART_RX_BUFFER_SIZE;
     dte_config.uart_config.tx_buffer_size = CONFIG_EXAMPLE_MODEM_UART_TX_BUFFER_SIZE;
     dte_config.uart_config.event_queue_size = CONFIG_EXAMPLE_MODEM_UART_EVENT_QUEUE_SIZE;
-    dte_config.task_stack_size = CONFIG_EXAMPLE_MODEM_UART_EVENT_TASK_STACK_SIZE * 2;
+    dte_config.task_stack_size = CONFIG_EXAMPLE_MODEM_UART_EVENT_TASK_STACK_SIZE;
     dte_config.task_priority = CONFIG_EXAMPLE_MODEM_UART_EVENT_TASK_PRIORITY;
     dte_config.dte_buffer_size = CONFIG_EXAMPLE_MODEM_UART_RX_BUFFER_SIZE / 2;
 
@@ -205,7 +209,7 @@ void app_main(void)
 #endif
     assert(dce);
     if (dte_config.uart_config.flow_control == ESP_MODEM_FLOW_CONTROL_HW) {
-        esp_err_t err = esp_modem_set_flow_control(dce, 2, 2);  //2/2 means HW Flow Control.
+        err = esp_modem_set_flow_control(dce, 2, 2);  //2/2 means HW Flow Control.
         if (err != ESP_OK) {
             ESP_LOGE(TAG, "Failed to set the set_flow_control mode");
             return;
@@ -246,23 +250,27 @@ void app_main(void)
 #error Invalid serial connection to modem.
 #endif
 
-    xEventGroupClearBits(event_group, CONNECT_BIT | GOT_DATA_BIT | USB_DISCONNECTED_BIT);
+#if CONFIG_EXAMPLE_DETECT_MODE_BEFORE_CONNECT
+    xEventGroupClearBits(event_group, CONNECT_BIT | GOT_DATA_BIT | USB_DISCONNECTED_BIT | DISCONNECT_BIT);
 
-    esp_err_t err = esp_modem_set_mode(dce, ESP_MODEM_MODE_DETECT);
+    err = esp_modem_set_mode(dce, ESP_MODEM_MODE_DETECT);
     if (err != ESP_OK) {
         ESP_LOGE(TAG, "esp_modem_set_mode(ESP_MODEM_MODE_DETECT) failed with %d", err);
         return;
     }
-    ESP_LOGI(TAG, "Mode detected!");
     esp_modem_dce_mode_t mode = esp_modem_get_mode(dce);
-    ESP_LOGI(TAG, "Current mode is : %d", mode);
-    if (mode != ESP_MODEM_MODE_COMMAND) {
+    ESP_LOGI(TAG, "Mode detection completed: current mode is: %d", mode);
+    if (mode == ESP_MODEM_MODE_DATA) {  // set back to command mode
         err = esp_modem_set_mode(dce, ESP_MODEM_MODE_COMMAND);
         if (err != ESP_OK) {
             ESP_LOGE(TAG, "esp_modem_set_mode(ESP_MODEM_MODE_COMMAND) failed with %d", err);
             return;
         }
+        ESP_LOGI(TAG, "Command mode restored");
     }
+#endif // CONFIG_EXAMPLE_DETECT_MODE_BEFORE_CONNECT
+
+    xEventGroupClearBits(event_group, CONNECT_BIT | GOT_DATA_BIT | USB_DISCONNECTED_BIT | DISCONNECT_BIT);
 
     /* Run the modem demo app */
 #if CONFIG_EXAMPLE_NEED_SIM_PIN == 1
@@ -317,19 +325,24 @@ void app_main(void)
     }
     /* Wait for IP address */
     ESP_LOGI(TAG, "Waiting for IP address");
-    xEventGroupWaitBits(event_group, CONNECT_BIT | USB_DISCONNECTED_BIT, pdFALSE, pdFALSE, portMAX_DELAY);
+    xEventGroupWaitBits(event_group, CONNECT_BIT | USB_DISCONNECTED_BIT | DISCONNECT_BIT, pdFALSE, pdFALSE,
+                        pdMS_TO_TICKS(60000));
     CHECK_USB_DISCONNECTION(event_group);
+    if ((xEventGroupGetBits(event_group) & CONNECT_BIT) != CONNECT_BIT) {
+        ESP_LOGW(TAG, "Modem not connected, switching back to the command mode");
+        err = esp_modem_set_mode(dce, ESP_MODEM_MODE_COMMAND);
+        if (err != ESP_OK) {
+            ESP_LOGE(TAG, "esp_modem_set_mode(ESP_MODEM_MODE_COMMAND) failed with %d", err);
+            return;
+        }
+        ESP_LOGI(TAG, "Command mode restored");
+        return;
+    }
 
     /* Config MQTT */
-#if ESP_IDF_VERSION >= ESP_IDF_VERSION_VAL(5, 0, 0)
     esp_mqtt_client_config_t mqtt_config = {
         .broker.address.uri = CONFIG_EXAMPLE_MQTT_BROKER_URI,
     };
-#else
-    esp_mqtt_client_config_t mqtt_config = {
-        .uri = CONFIG_EXAMPLE_MQTT_BROKER_URI,
-    };
-#endif
     esp_mqtt_client_handle_t mqtt_client = esp_mqtt_client_init(&mqtt_config);
     esp_mqtt_client_register_event(mqtt_client, ESP_EVENT_ANY_ID, mqtt_event_handler, NULL);
     esp_mqtt_client_start(mqtt_client);
@@ -345,7 +358,7 @@ void app_main(void)
     ESP_LOGI(TAG, "Signal quality: rssi=%d, ber=%d", rssi, ber);
     esp_modem_pause_net(dce, false);
     esp_mqtt_client_publish(mqtt_client, CONFIG_EXAMPLE_MQTT_TEST_TOPIC, CONFIG_EXAMPLE_MQTT_TEST_DATA, 0, 0, 0);
-#endif
+#endif // CONFIG_EXAMPLE_PAUSE_NETIF_TO_CHECK_SIGNAL
 
     ESP_LOGI(TAG, "Waiting for MQTT data");
     xEventGroupWaitBits(event_group, GOT_DATA_BIT | USB_DISCONNECTED_BIT, pdFALSE, pdFALSE, portMAX_DELAY);

components/esp_modem/examples/pppos_client/pytest_pppos_client.py

@@ -12,7 +12,7 @@ def test_pppos_connect(dut):
       4. checks that the client cleanly disconnects
     """
     # Check the sequence of connecting, publishing, disconnecting
-    dut.expect('Modem Connect to PPP Server')
+    dut.expect('Modem Connect to PPP Server', timeout=90)
     # Check for MQTT connection and the data event
     dut.expect('MQTT_EVENT_CONNECTED')
     dut.expect('MQTT_EVENT_DATA')

components/esp_modem/examples/pppos_client/sdkconfig.ci.sim800_c3

@@ -14,4 +14,4 @@ CONFIG_EXAMPLE_MQTT_TEST_TOPIC="/ci/esp-modem/pppos-client"
 CONFIG_EXAMPLE_PAUSE_NETIF_TO_CHECK_SIGNAL=y
 CONFIG_ESP_SYSTEM_PANIC_PRINT_HALT=y
 CONFIG_ESP32_PANIC_PRINT_HALT=y
-CONFIG_LOG_DEFAULT_LEVEL_DEBUG=y
+CONFIG_EXAMPLE_DETECT_MODE_BEFORE_CONNECT=y

components/esp_modem/examples/simple_cmux_client/sdkconfig.ci.sim800_cmux

@@ -16,3 +16,4 @@ CONFIG_COMPILER_CXX_EXCEPTIONS=y
 CONFIG_ESP_MAIN_TASK_STACK_SIZE=8192
 CONFIG_EXAMPLE_CLOSE_CMUX_AT_END=y
 CONFIG_EXAMPLE_MQTT_TEST_TOPIC="/ci/esp-modem/pppos-client"
+CONFIG_BROKER_URI="mqtt://mqtt.eclipseprojects.io"

components/esp_modem/src/esp_modem_c_api.cpp

@@ -516,3 +516,11 @@ extern "C" esp_err_t esp_modem_pause_net(esp_modem_dce_t *dce_wrap, bool pause)
     }
     return command_response_to_esp_err(dce_wrap->dce->pause_netif(pause));
 }
+
+extern "C" esp_err_t esp_modem_hang_up(esp_modem_dce_t *dce_wrap)
+{
+    if (dce_wrap == nullptr || dce_wrap->dce == nullptr) {
+        return ESP_ERR_INVALID_ARG;
+    }
+    return command_response_to_esp_err(dce_wrap->dce->hang_up());
+}