How to maintain persistent HTTPS connection

[AaronConvery]

[ ] I have read the Troubleshooting section of the ReadMe

What type of issues is this?

Question or request for help

What are you working with?

Modem: SIM7600CE-T Main processor board: ESP32 - WROVER -IE TinyGSM version: 0.11.7 Code: All sensitive data is redacted

define TINY_GSM_MODEM_SIM7600

define SerialMon Serial

define SerialAT Serial1

define DUMP_AT_COMMANDS

define TINY_GSM_DEBUG SerialMon

define TINY_GSM_TEST_GPRS true

define TINY_GSM_TEST_TCP true

define GSM_PIN ""

const char apn[] = "REDACTED"; const char gprsUser[] = "REDACTED"; const char gprsPass[] = "REDACTED";

const char server[] = "REDACTED"; const char resource[] = "REDACTED"; const int port = 443;

include

include

include "SSLClient.h"

include "utilities.h"

include "certs.h"

include

include

ifdef DUMP_AT_COMMANDS

include

StreamDebugger debugger(SerialAT, SerialMon); TinyGsm modem(debugger);

else

TinyGsm modem(SerialAT);

endif

define TWATCHDOG_TIMEOUT 120

TinyGsmClient base_client(modem, 0); SSLClient secure_layer(&base_client); HttpClient client = HttpClient(secure_layer, server, port);

void setup() { SerialMon.begin(115200); delay(10);

SerialAT.begin(UART_BAUD, SERIAL_8N1, MODEM_RX, MODEM_TX);

pinMode(LED_PIN, OUTPUT);
digitalWrite(LED_PIN, HIGH);

pinMode(MODEM_PWRKEY, OUTPUT);
digitalWrite(MODEM_PWRKEY, HIGH);
delay(300);
digitalWrite(MODEM_PWRKEY, LOW);

pinMode(MODEM_FLIGHT, OUTPUT);
digitalWrite(MODEM_FLIGHT, HIGH);

secure_layer.setCACert(root_ca);

}

void light_sleep(uint32_t sec) { esp_sleep_enable_timer_wakeup(sec * 1000000ULL); esp_light_sleep_start(); }

bool isConnected = false;

void loop() { if (!isConnected) { DBG("Initializing modem..."); if (!modem.init()) { if (!modem.restart()) { DBG("Failed to restart modem, delaying 10s and retrying"); delay(10000); return; } }

    String ret;
    do {
        ret = modem.setNetworkMode(54);
        delay(500);
    } while (!ret);

    DBG("Waiting for network...");
    if (!modem.waitForNetwork(600000L)) {
        DBG("Network not available, sleeping for 10 seconds");
        light_sleep(10);
        return;
    }

    if (modem.isNetworkConnected()) {
        DBG("Network connected");
    }

    DBG("Connecting to", apn);
    if (!modem.gprsConnect(apn, gprsUser, gprsPass)) {
        DBG("Failed to connect to GPRS, sleeping for 10 seconds");
        light_sleep(10);
        return;
    }

    isConnected = modem.isGprsConnected();
    DBG("GPRS status:", isConnected ? "connected" : "not connected");
}

if (isConnected) {
    DBG("Making GET request securely...");
    client.beginRequest();
    client.get(resource);
    client.sendHeader("Connection", "keep-alive");
    client.endRequest();

    int status_code = client.responseStatusCode();
    String response = client.responseBody();

    Serial.print("Status code: ");
    Serial.println(status_code);
    Serial.print("Response: ");
    Serial.println(response);

    if (status_code < 0) {
        DBG("Error encountered. Reconnecting...");
        isConnected = false;
    }
} else {
    DBG("Lost connection. Reinitializing...");
    delay(5000);
    return;
}

delay(500);

}

Scenario, steps to reproduce

I want the HTTPS connection to remain active after first initialising in order to receive updates on the data it is trying to request

Expected result

I want to receive live updates on the data requested in the get request

Actual result

The connection is being established and a successful get request is made but then the connection is being closed despite me telling it to stay alive both in my header and on the server code. It is not explicitly being told to close yet it still is

Debug and AT command log

All sensitive data has been redacted 16:58:19.674 -> AT+CIPRXGET=2,0,63 16:58:19.707 -> 16:58:19.707 -> +CIPRXGET: 2,0,63,2 16:58:19.707 -> [REDACTED] 16:58:19.707 -> 16:58:19.707 -> OK 16:58:19.707 -> AT+CIPRXGET=2,0,2 16:58:19.707 -> 16:58:19.707 -> +CIPRXGET: 2,0,2,0 16:58:19.707 -> [REDACTED] 16:58:19.707 -> 16:58:19.707 -> OK 16:58:19.707 -> Status code: 200 16:58:19.707 -> Response: OPEN_VALVE 16:58:20.225 -> [14802] Making GET request securely... 16:58:20.225 -> AT+CIPCLOSE=0 16:58:20.225 -> 16:58:20.225 -> +CIPCLOSE: 0,4 16:58:20.225 -> 16:58:20.225 -> ERROR 16:58:20.225 -> AT+CIPRXGET=1 16:58:20.225 -> 16:58:20.225 -> OK 16:58:20.225 -> AT+CIPOPEN=0,"TCP","[REDACTED]",443 16:58:20.257 -> 16:58:20.257 -> OK 16:58:20.386 -> 16:58:20.386 -> +CIPOPEN: 0,0 16:58:20.386 -> AT+CIPCLOSE=0 16:58:20.418 -> 16:58:20.418 -> OK 16:59:20.416 -> Status code: -3 16:59:20.416 -> Response:

[droidblastnz]

Same issue but with MQTT here see the last modded code hope it helps. If you are using a consumer SIM it will be disconnected mine was repeating the disconnect very 23-24hrs.

[AaronConvery]

Same issue but with MQTT here see the last modded code hope it helps. If you are using a consumer SIM it will be disconnected mine was repeating the disconnect very 23-24hrs.

Mine is currently closing the connection as soon as it makes the first get request, if it was 18-24hours that would actually be somewhat manageable, did you ever encounter this or was it a fairly persistent connection straight away?

[droidblastnz]

Mine was the use of a consumer SIM versus M2M SIM or at least suspected that but it now stays connected. Lots of reports re psu voltage, signal etc but I went through each of those and none where my issue.

The only other advice is to use the native AT commands to build your case up but in some cases you cant or install a LAMP or IIS instance local and then monitor the logs to see what is happening. I needed to do this with MQTT docker and also FTP Filezilla as mu host doesnt allow me to see logs. It highlighted issues in my code now after a year of coding my IOT remote device works as it should....