Improve the GSM connection procedure

[gideonmaina]

The connectGSM() function can be modified to return a boolean type to determine whether GPRS functionality is available on setup. The return value will determine whether or not to switch to a WiFi connection.

The procedure can be improved by:

1. Setting additional flags:

• SIM_available/usable: This will determine whether we can use the SIM even if GPRS is not available
• GPRS_active: This can be set after running a test to ping a DNS

2. Steps to initiate the service

• The obvious is to check for serial communication with the GSM chip. If improperly configured set gsm_capable flag to false
• Check if SIM is available. There are a few ways to do this. e.g AT+CCID
• Check if PIN is set/and or attempt to set pin:
• Check whether the module is registered to a network. At this point, the SIM_available flag can be set.
• Enable GPRS
• Run a connection test and set the GPRS_active flag

3. Audit the amount of time it takes to connect to a network. A warmup time delay would be suitable during the initialization process.

*** Suggestions ***
Rename function to initGSM(). This function can be called when restarting the GSM either via hardware or software serial.

/****
 //ToDo:
 1.  Change return type to boolean
 2.  Set flag to check if SIM is inserted/usable
 //? change function name to initGSM() maybe to set different flags. GSM restart can call this function;
 ***/
void connectGSM()
{

	int retry_count = 0;

	fonaSerial->begin(4800);
	if (!fona.begin(*fonaSerial))
	{
		debug_outln(F("Couldn't find FONA"), DEBUG_MIN_INFO);

		debug_outln(F("Switching to Wifi"), DEBUG_MIN_INFO);
		gsm_capable = 0;
		connectWifi(); // ToDo: Return false instead
	}
	else
	{
		debug_outln(F("FONA is OK"), DEBUG_MIN_INFO); //
													  // ToDO: Check if SIM is installed. Run CCID
		unlock_pin();								  // ToDO check if PIN is set. If not return false and set SIM usable and GPRS capable flags to false

		char imei[16] = {0}; // MUST use a 16 character buffer for IMEI!
		uint8_t imeiLen = fona.getIMEI(imei);
		if (imeiLen > 0)
		{
			debug_outln(F("Module IMEI: "), DEBUG_MIN_INFO);
			debug_out(String(imei), DEBUG_MIN_INFO);
		}

		fona.setGPRSNetworkSettings(F("internet"), F(""), F(""));

		while ((fona.getNetworkStatus() != GSM_CONNECTED) && (retry_count < 40))
		{
			Serial.println("Not registered on network");
			delay(5000); // ?: Takes 2.5mins until until retry_count=30. It will take 5sec longer every other time and GSM is always restarted!
			retry_count++;

			if (retry_count > 30) // ?: Review this. Seems to be increasing the connect time. Maybe try 3 times
			{
				delay(5000);
				restart_GSM();
			}

			flushSerial();
		}

		if (fona.getNetworkStatus() != GSM_CONNECTED) // ToDo: Return false and enable wifi connect somewhere else
		{
			String fss(cfg::fs_ssid);
			display_debug(fss.substring(0, 16), fss.substring(16));

			wifiConfig();
			if (fona.getNetworkStatus() != GSM_CONNECTED)
			{
				retry_count = 0;
				while ((fona.getNetworkStatus() != GSM_CONNECTED) && (retry_count < 20))
				{
					delay(500);
					debug_outln(".", DEBUG_MIN_INFO);
					retry_count++;
				}
				debug_outln("", DEBUG_MIN_INFO);
			}
		}
		else
		{
			enableGPRS(); // ToDO: Expect a boolean value from this and set GPRS flag
			Serial.println("GPRS ENABLED");
		}
	}
}