Modem Hard Reset - expose the function to users

Troubleshooting
2

This works a treat using Rikkas Electronsample

Fault Tolerance Code

I modified the checks it carries out to see if the AT / OK stops coming back, (and got rid of the PING as it doesn’t work)

void ConnectionCheck::loop() {
	#define MODEM_POLL_FOR_OK_MSEC 10000
	// Check cellular status - used for event logging mostly
	bool temp = Cellular.ready();
	if (temp != isCellularReady) {
		// Cellular state changed
		isCellularReady = temp;
		Log.info("cellular %s", isCellularReady ? "up" : "down");
	}



	if (millis() - listenWaitForOK >= MODEM_POLL_FOR_OK_MSEC) {
		listenWaitForOK = millis();
		if (!CheckForModemResponseOK()){
			Log.info("Modem didn't respond, rebooting modem (not rebooting processor)");
			fullModemReset();
		}
	}


	if (Cellular.listening()) {
		// Entered listening mode (blinking blue). Could be from holding down the MODE button, or
		// by repeated connection failures, see: https://github.com/spark/firmware/issues/687
		if (listeningStart == 0) {
			listeningStart = millis();
			Log.info("entered listening mode");
		}
		else {
			if (listenWaitForReboot != 0 && millis() - listeningStart >= listenWaitForReboot) {
				// Reboot
				fullModemReset();
			}
		}
	}
}


bool ConnectionCheck::CheckForModemResponseOK(){
	if (RESP_OK == Cellular.command("AT\r\n")){
		return true;
	}
	return false;
}

Then if anything goes wrong I simply wiggle the pins on the reset line of the Modem, clear the state, and reconnect.


void ConnectionCheck::fullModemReset() {

	Log.info("fullModemReset - resetting modem");

	// Reset the modem and SIM card
	// 16:MT silent reset (with detach from network and saving of NVM parameters), with reset of the SIM card
	//Cellular.command(30000, "AT+CFUN=16\r\n");
	ModemHardReset();
	
	delay(1000);

	//tell the processor to clear any state. 
	Cellular.disconnect();
	cloud_connect();


}


//firmware\hal\src\electron\modem\mdm_hal.cpp
void ConnectionCheck::ModemHardReset(){
 Log.info("[ Modem  Hard reset ]");
    const unsigned delay = 100;
    HAL_GPIO_Write(RESET_UC, 0);
    HAL_Delay_Milliseconds(delay);
    HAL_GPIO_Write(RESET_UC, 1);
}