GSM: limit the number of internal state machine retries to 6

Author: pennam

libraries/GSM/src/GSM.cpp

@@ -81,6 +81,7 @@ int arduino::GSMClass::begin(const char* pin, const char* apn, const char* usern
 
   _context->set_sim_pin(pin);
 
+  _device->set_retry_timeout_array(_retry_timeout, sizeof(_retry_timeout) / sizeof(_retry_timeout[0]));
 #if GSM_DEBUG_ENABLE
   _device->attach(mbed::callback(this, &GSMClass::onStatusChange));
 #endif

libraries/GSM/src/GSM.h

@@ -154,6 +154,11 @@ class GSMClass : public MbedSocketClass {
   mbed::CellularDevice* _device = nullptr;
   bool _at_debug = false;
 
+  /* Internal cellular state machine retries. Values are in seconds.
+   * This array also defines the maximum number of retries to 6
+   */
+  const uint16_t _retry_timeout[6] = {1, 2, 4, 8, 16, 32};
+
 #if GSM_DEBUG_ENABLE
   static constexpr int RSSI_UNKNOWN = 99;
   static const char * const sim_state_str[];