pppos_client example hangs when I loop it

[hans-jorgen]

I am trying to use a sim800 circuit and am fooling around with the pppos example. I am using esp-idf 4.0.

The example works fine, but when I add a loop to take down and up the PPP connection it freezes waiting for a semaphore in tcpip.c.

What I've done:

Started a new project with the visualgdb wizard in Visual Studio
Setup correct APN, TXD and RXD pin in example configuration.
Tested the base project without any changes, works fine.

Modified app_main() in pppos_client_main.c thusly:

Code: [Select all] [Expand/Collapse]

1.     ESP_ERROR_CHECK(esp_modem_add_event_handler(dte, modem_event_handler, NULL));
2.     /* create dce object */
3. #if CONFIG_EXAMPLE_MODEM_DEVICE_SIM800
4.     modem_dce_t *dce = sim800_init(dte);
5. #elif CONFIG_EXAMPLE_MODEM_DEVICE_BG96
6.     modem_dce_t *dce = bg96_init(dte);
7. #else
8. #error "Unsupported DCE"
9. #endif
10.     ESP_ERROR_CHECK(dce->set_flow_ctrl(dce, MODEM_FLOW_CONTROL_NONE));
11.     ESP_ERROR_CHECK(dce->store_profile(dce));
12.     while (1)
13.     {
14.         /* Print Module ID, Operator, IMEI, IMSI */
15.         ESP_LOGI(TAG, "Module: %s", dce->name);
16.         ESP_LOGI(TAG, "Operator: %s", dce->oper);
17.         ESP_LOGI(TAG, "IMEI: %s", dce->imei);
18.         ESP_LOGI(TAG, "IMSI: %s", dce->imsi);
19.         /* Get signal quality */
20.         uint32_t rssi = 0, ber = 0;
21.         ESP_ERROR_CHECK(dce->get_signal_quality(dce, &rssi, &ber));
22.         ESP_LOGI(TAG, "rssi: %d, ber: %d", rssi, ber);
23.         /* Get battery voltage */
24.         uint32_t voltage = 0, bcs = 0, bcl = 0;
25.         ESP_ERROR_CHECK(dce->get_battery_status(dce, &bcs, &bcl, &voltage));
26.         ESP_LOGI(TAG, "Battery voltage: %d mV", voltage);
27.         /* Setup PPP environment */
28.         esp_modem_setup_ppp(dte);
29.         /* Wait for IP address */
30.         xEventGroupWaitBits(event_group, CONNECT_BIT, pdTRUE, pdTRUE, portMAX_DELAY);
31.         /* Config MQTT */
32.         esp_mqtt_client_config_t mqtt_config = {
33.             .uri = BROKER_URL,
34.             .event_handle = mqtt_event_handler,
35.         };
36.         esp_mqtt_client_handle_t mqtt_client = esp_mqtt_client_init(&mqtt_config);
37.         esp_mqtt_client_start(mqtt_client);
38.         xEventGroupWaitBits(event_group, GOT_DATA_BIT, pdTRUE, pdTRUE, portMAX_DELAY);
39.         esp_mqtt_client_destroy(mqtt_client);
40.         /* Exit PPP mode */
41.         ESP_ERROR_CHECK(esp_modem_exit_ppp(dte));
42.         xEventGroupWaitBits(event_group, STOP_BIT, pdTRUE, pdTRUE, portMAX_DELAY);
43.         #if CONFIG_EXAMPLE_SEND_MSG
44.         const char *message = "Welcome to ESP32!";
45.         ESP_ERROR_CHECK(example_send_message_text(dce, CONFIG_EXAMPLE_SEND_MSG_PEER_PHONE_NUMBER, message));
46.         ESP_LOGI(TAG, "Send send message [%s] ok", message);
47.         #endif
48.     }
49.     /* Power down module */
50.     ESP_ERROR_CHECK(dce->power_down(dce));

GeSHi © Codebox Plus Extension

This ought to init ppp, do stuff, close ppp again and again.

On the second loop it freezes waitning for a semaphore in tcpip_api_call(), this specific line:

Code: Select all

  sys_arch_sem_wait(TCPIP_MSG_VAR_REF(msg).msg.api_call.sem, 0);

If I modify the timeout 0 to 10000 it timeouts and continues and on every following loop the code works as I envisioned it would, it does not get stuck on that semaphore on laps 1 and 3-eternity.

This seems to be because the TCP/IP stack is not in the expected location on the second lap. It is itself already stuck on that semaphore. Stepping through the code it seems like the TCP/IP stack normally waits for an mbox, sent by tcpip_api_call I presume, but somehow it gets "out of sync" on lap 2 in the loop.

It seems to get out of sync in esp_modem_exit_ppp() inbetween the following two lines:

Code: Select all

    MODEM_CHECK(dte->change_mode(dte, MODEM_COMMAND_MODE) == ESP_OK, "enter command mode failed", err);
    /* Hang up */
    MODEM_CHECK(dce->hang_up(dce) == ESP_OK, "hang up failed", err);

I've tried all my 1337 ninja skills on finding clues as to why, but I have been unsuccessful. Anyone else recognize this?

[sumesh]

did u manage to fix this issue?
i am also having the same issue.. cant change mode back to cmd before hanging up