MKRGSM library not reliable

[alanoatwork]

I've posted this before, but I'll try again. My code is pretty simple. I check for SMS messages and then reply back using Hologram's network. I'm using the latest MKRGSM library 1.3.1. I also have a 1400 mAhr lithium battery connected so I'm confident that I don't have a hardware issue related to modem current.

Here's my code:

#include <MKRGSM.h>
const char PINNUMBER[] = " ";
const char GPRS_APN[] = "hologram";
const char GPRS_LOGIN[] = " ";
const char GPRS_PASSWORD[] = " ";

String HOLOGRAM_DEVICE_KEY = "********";
String HOLOGRAM_TOPIC = "_SOCKETAPI_";

GSMClient client;
GPRS gprs;
GSM gsm(1);                                             // Enable debug
GSM_SMS sms;
GSMScanner scan;

char server[] = "cloudsocket.hologram.io";
int port = 9999;
boolean isSMSAvailable = false;
char sms_message[145];

void setup() {
  Serial.begin(115200);
  //while(!Serial);

  scan.begin();
  connectGSM();
}

void connectGSM() {
  boolean connected = false;

  while (!connected) {
    Serial.println("Begin GSM Access");
      
    if ((gsm.begin() == GSM_READY) &&
        (gprs.attachGPRS(GPRS_APN, GPRS_LOGIN, GPRS_PASSWORD) == GPRS_READY)) {
      connected = true;
      Serial.println("GSM Access Success");
      Serial.println(scan.getCurrentCarrier());
    } 
    else {
      Serial.println("Not connected");
      delay(1000);
    }
  }
}

void loop() {
  if(Serial.available()) {
    char c = Serial.read();
    if(c == 'e')
       MODEM.debug();
    if(c == 'd')
         MODEM.noDebug();
  }
  
  // Get any new incoming txt messages
  int c;
  if (sms.available()) {
    int i = 0;
    while ((c = sms.read()) != -1) {
      sms_message[i++] = (char)c;
    }
    sms_message[i] = '\0';        // Terminate message
    isSMSAvailable = true;
    sms.flush();
  }

  if(gsm.isAccessAlive()) {
    if(gprs.status() != GPRS_READY) {
      if(gprs.attachGPRS(GPRS_APN, GPRS_LOGIN, GPRS_PASSWORD) == GPRS_READY)
        Serial.println("GPRS ready!");
      else
        Serial.println("GRPS not ready!");
    }
  }
  else {
    Serial.println("Reconnect to GSM...");
    connectGSM();
  }

  // Send message back through hologram
  if(isSMSAvailable) {
    isSMSAvailable = false;

    if (client.connect(server, port)) {
      client.print("{\"k\":\"" + HOLOGRAM_DEVICE_KEY + "\",\"d\":\"");
      client.print(sms_message);
      client.println("\",\"t\":\""+HOLOGRAM_TOPIC+"\"}");
      client.stop();
    }
    else {
      MODEM.send("AT+USOER");
    }
  }

  delay(1000);
}`

It takes anywhere from a few days to a week or more to exhibit the problem. My logs typically look like this, where the incoming SMS message, "Jdjd", gets received and then repeated back to me via Hologram's network.

OK
AT+CMGL="REC UNREAD"

+CMGL: 19,"REC UNREAD","+19495472010",,"18/11/14,03:53:24+00"
Jdjd

OK
AT+CMGD=19

OK
AT+CREG?

+CREG: 0,5

OK
AT+USOCR=6

+USOCR: 0

OK
AT+USOCO=0,"cloudsocket.hologram.io",9999

OK
AT+USOWR=0,21,"7B226B223A22433E383375242B57222C2264223A22"

+USOWR: 0,21

OK
AT+USOWR=0,4,"4A646A64"

+USOWR: 0,4

OK
AT+USOWR=0,20,"222C2274223A225F534F434B45544150495F227D"

+USOWR: 0,20

OK
AT+USOWR=0,2,"0D0A"

+USOWR: 0,2

OK
AT+USOCL=0

OK
AT+CMGL="REC UNREAD"

OK
AT+CREG?

+CREG: 0,5`

However, after a week or so this happens:

`OK
AT+CMGL="REC UNREAD"

+CMGL: 19,"REC UNREAD","+19495472010",,"18/11/20,19:51:00+00"
JDJDJ

OK
AT+CMGD=19

OK
AT+CREG?

+CREG: 0,5

OK
AT+USOCR=6

+USOCR: 0

OK
AT+USOCO=0,"cloudsocket.hologram.io",9999

ERROR

+UUSOCL: 0
AT+USOCL=0

ERROR
AT+CMGL="REC UNREAD"

OK
AT+CREG?

+CREG: 0,5

OK
AT+CMGL="REC UNREAD"

OK
AT+CREG?

+CREG: 0,5

From then on, the library is never able to recover.

Any help would be greatly appreciated. The code I submitted is a stripped down version of my application. I've been wanting to release my application using the MKRGSM board but I've been haunted by this issue. I see there's some asynchronous options that aren't well documented and I'm reluctant to use this approach - besides, shouldn't this library be rock solid as documented!

[Rocketct]

Hi @alanoatwork, i'm work on this issue, could you test the same sketch by imposing a timeout adding in the connectGSM() gprs.setTimeout(180000); and gsm.setTimeout(180000) this should allow to come back to .loop function after 3 minutes and retry from samd waiting.

[alanoatwork]

I'll give this a try if that's what you're suggesting:

void connectGSM() {
  gprs.setTimeout(180000);
  gsm.setTimeout(180000);
  
  boolean connected = false;

  while (!connected) {
    Serial.println("Begin GSM Access");
      
    if ((gsm.begin() == GSM_READY) &&
        (gprs.attachGPRS(GPRS_APN, GPRS_LOGIN, GPRS_PASSWORD) == GPRS_READY)) {
      connected = true;
      Serial.println("GSM Access Success");
      Serial.println(scan.getCurrentCarrier());
    } 
    else {
      Serial.println("Not connected");
      delay(1000);
    }
  }
}

[Rocketct]

@alanoatwork yes exactly in this way.

[alanoatwork]

Two weeks and so far so good. Why aren't these timeouts set by default so perhaps others don't experience the difficulty that I faced?

[alanoatwork]

After weeks of testing, the library still doesn't work correctly. I went a couple of weeks with no issue, so I turned-off debug and let my application run. I went about a week before the board just stopped responding. So I enabled debug again and I'll let it run until it dies. This is super frustrating that the board isn't able to recover. I noticed that the lockups occur much sooner if I don't connect an external 1400 mAh lithium cell, but even with the cell connected lockups occur eventually. Does the async approach solve this issue? Can someone pipe in here and explain the advantages/disadvantages between these approaches and whether or not I should be exploring this option.

[alanoatwork]

It died within the first day. Here's my log...

OK
AT+CMGL="REC UNREAD"

OK
AT+CREG?

+CREG: 0,5

OK
AT+CMGL="REC UNREAD"

OK
AT+CREG?

+CREG: 0,5

OK

UPSDD
AT+CMGL="REC UNREAD"

OK

[eiriksels]

When you get the freeze, does the board recover with a reboot or removing and putting the power back on? If not, I guess it is the same issue as I see. I would be interested if you have found any solutions. My experience is that I can reproduce the issue quite fast when placing my unit in a car and driving around with varying network conditions.

[alanoatwork]

My setup always recovers with a reboot.

[eiriksels]

I am now running your sketch alanoatwork. Only difference I made was using timeout of 20 sec for the gsm/gprs. So far it is working good, but only tested for 2 days. I hope you get some feedback soon on the issues you are facing from the developers.

One suggestion as you mentioned that battery voltage does seem to influence the stability:

IF or a WHILE condition of analogRead(ADC_BATTERY)*(4.3/1023<3.7) where you do not let it upload or have communications with the modem below a certain battery voltage.

[alanoatwork]

I've been running my sketch while connected to the USB port AND with a battery - just to make sure that the issues weren't hardware related. I'll try a longer timeout and see if that helps.

[Nels52]

@alanoatwork
For what it is worth I have a sketch which uses the GSM, GPRS, and GSMClient state machines to periodically report to the hologram cloud. Whenever I experience any error such as the failed TCP socket connection to "cloudsocket.hologram.io",9999 referenced above my sketch resets everything from the beginning (gsm.begin() and gprs.attachGPRS()). The gsm.begin() invokes a Modem class method that toggles the resetPin. This isn't very elegant but my sketch has been running unattended for more than 2 months now.

[alanoatwork]

@Nels52 Thanks for reaching out. I'm not very familiar with GitHub and now see that it's pretty simple to reach out to another user! I've put my synchronous application on hold and just coded up my app based on your asynchronous HomeMonitor5 code. I was hoping that the switch from the Dash board to the MKR board would be relatively easy, but here I am 6 months later with an unstable product. Your framework is nicely written and fits into my code pretty easily, so thanks very much for sharing it with us. I'll report back if anyone is interested how this works out for me. I would be interested to know if you've made any changes since HomeMonitor5 as I don't profess to understand all the possible errors and corner cases that could arise when trying to communicate with Hologram.