AWS IOT with SIMCOM7600SA

[adfo0]

Hello everyone. I am working with an ESP32 board, with a SIMCOM7600SA modem.

I am using the SSL Client library to connect to AWS IOT Core. But I have some problems with the stability of the connection.

In some moments I get these errors, sometimes in the first connection attempt. or also after a few minutes.

After a few attempts to reconnect, it works again.

(SSLClient)(SSL_ERROR)(connect): Failed to connect using m_client. Are you connected to the internet?
(SSLClient)(SSL_ERROR)(connected): Not connected because write error is set
(SSLClient)(SSL_ERROR)(m_print_ssl_error): SSL_CLIENT_CONNECT_FAIL
[165043] ### Unhandled: ERROR

What could be the problem ? or is it normal?

Thanks

[prototypicalpro]

I haven't tried using SSLClient with cellular myself, but from what I've gathered from issue threads it can be unreliable depending on the module, current cell signal, and cell provider among other things. What might help is using something like the TinyGsmSecureClient instead of SSLClient, which utilizes the TLS stack available on the SIMCOM itself--I'm not sure whether or not that client supports mTLS, however, so it might not work for AWS IoT Core. Otherwise if you have to stick with SSLClient this issue comment might be useful; other than that I'm afraid I don't have any suggestions.

[adfo0]

Thanks @prototypicalpro

[adfo0]

Hello again.

I'm still working with this module and AWS. And although it works most of the time fine. But today I had a new error message and the module could not reconnect.

07:46:59.982 -> (SSLClient)(SSL_ERROR)(connected): Not connected because write error is set
07:46:59.982 -> (SSLClient)(SSL_ERROR)(m_print_ssl_error): SSL_CLIENT_CONNECT_FAIL
07:47:15.029 -> (SSLClient)(SSL_ERROR)(connect): Failed to connect using m_client. Are you connected to the internet?
07:47:20.052 -> (SSLClient)(SSL_ERROR)(connected): Not connected because write error is set
07:47:20.052 -> (SSLClient)(SSL_ERROR)(m_print_ssl_error): SSL_CLIENT_CONNECT_FAIL
07:47:55.500 -> (SSLClient)(SSL_ERROR)(m_run_until): SSL internals timed out! This could be an internal error, bad data sent from the server, or data being discarded due to a buffer overflow. If you are using Ethernet, did you modify the library properly (see README)?
07:47:55.500 -> (SSLClient)(SSL_ERROR)(connected): Not connected because write error is set
07:47:55.500 -> (SSLClient)(SSL_ERROR)(m_print_ssl_error): SSL_BR_WRITE_ERROR
07:47:55.500 -> (SSLClient)(SSL_ERROR)(m_start_ssl): Failed to initlalize the SSL layer
07:47:55.500 -> (SSLClient)(SSL_ERROR)(m_print_br_error): Unknown error code: 0

Any experience with this problem? any possible cause?

Thank you

[woodlist]

Are you sure that you have correctly set the data/time for SSL engine (sslClient.setVerificationTime where the "sslClient" is user defined name of client. My example was defined as "SSLClient sslClient(GSMclient, TAs, (size_t)TAs_NUM, rand_pin);")? I have an tested portion of code for this task. See beneath: `// https://www.geeksforgeeks.org/find-number-of-days-between-two-given-dates/ using namespace std; unsigned long Seconds; // A date has day 'd', month 'm' and year 'y' struct Date { int d, m, y; };

// To store number of days in // all months from January to Dec. const int monthDays[12] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }; int year3 = 0; int month3 = 0; int day3 = 0; int hour3 = 0; int min3 = 0; int sec3 = 0; float timezone = 0;

if (modem.getNetworkTime(&year3, &month3, &day3, &hour3, &min3, &sec3, &timezone)) { calctime(); }

int countLeapYears(Date d) { int years = d.y;

// Check if the current year needs to be // considered for the count of leap years // or not if (d.m <= 2) years--;

// An year is a leap year if it // is a multiple of 4, // multiple of 400 and not a // multiple of 100. return years / 4 - years / 100 + years / 400; }

// This function returns number of // days between two given dates int getDifference(Date dt1, Date dt2) { // COUNT TOTAL NUMBER OF DAYS // BEFORE FIRST DATE 'dt1'

// initialize count using years and day long int n1 = dt1.y * 365 + dt1.d;

// Add days for months in given date for (int i = 0; i < dt1.m - 1; i++) n1 += monthDays[i];

// Since every leap year is of 366 days, // Add a day for every leap year n1 += countLeapYears(dt1);

// SIMILARLY, COUNT TOTAL NUMBER OF // DAYS BEFORE 'dt2'

long int n2 = dt2.y * 365 + dt2.d; for (int i = 0; i < dt2.m - 1; i++) n2 += monthDays[i]; n2 += countLeapYears(dt2);

// return difference between two counts return (n2 - n1); }

int calctime() { Date dt1 = { 1, 1, 0 }; Date dt2 = { day3, month3, year3 }; Seconds = hour3 * 3600 + min3 * 60 + sec3; sslClient.setVerificationTime((uint32_t)getDifference(dt1, dt2), (uint32_t)Seconds); SerialMon.println( "Difference between two dates is " + String(getDifference(dt1, dt2)) + " days"); return 0; }`

[adfo0]

Hi @woodlist, this configuration should be done when the connection is for a long period of time? I did not know that it was necessary. Thanks for your answer

[woodlist]

Hi @woodlist, this configuration should be done when the connection is for a long period of time? I did not know that it was necessary. Thanks for your answer

How is your experience with suggested fix?

[adfo0]

Finally, the problems were caused by the connectivity with the 3G network.

Apparently it is very sensitive to signal quality. When changing the antenna and looking for a sector with good signal quality, the problem did not appear again, before making any change.