user61851: I am building a simple telnet style interface for experimental settings on my project. I am getting all the serial output sent to serial (and USB to PC). The code works fine, but if I try to read from Serial or check 'Serial.available()' I will get:

Fatal exception 9(LoadStoreAlignmentCause)

Definition:
bool pridaj_cely(uint8_t source_from=0, uint8_t line_LCD=0);
The code:
bool Vstup::pridaj_cely(uint8_t source_from, uint8_t line_LCD) {
  uint8_t i = 0;
  Serial.println(F("one piece input read"));
  switch (origin) {
    case 0: { //Serial
        int16_t znak = -1;
        while (Serial.available() < 0) {
          Serial.print(F("."));
          delay(100);
        }
        Serial.print(F("Somothing is comming"));
        while (Serial.available() > 0) {
          celok[i] = Serial.read();
          if (i < 12)  i++;
        }
      }
      break;
  }
  return 1;
}

Code of Priojenie:
bool pripojenie(bool force_it = 0) {
  Serial.println(("Beginning connection routine"));
  kolo = millis();
  while (!WiFi.isConnected()) {
    int8_t sieti = WiFi.scanComplete();
    Serial.printf("Search result %X", sieti);
    switch (sieti) {
      case -2:
        Serial.println(("\tSearch begins"));
        WiFi.scanNetworks(1);
        delay(50);
        break;
      case -1:
        Serial.print(("."));
        delay(300);
        break;
      default: //This is the relevant case
        Vstup odpoved;
        Serial.ciara;
        Serial.ciara;
        Serial.printf(("Found %X networks"), sieti);
        Serial.ciara;
        Serial.println();
        for (uint8_t i = 0; i < sieti; i++) {
          Serial.printf("%d: %s, Kanál:%d (%ddBm) %s\n", i, WiFi.SSID(i).c_str(), WiFi.channel(i), WiFi.RSSI(i), WiFi.encryptionType(i) == ENC_TYPE_NONE ? "Otvorena" : "");
        }
        Serial.ciara;
        Serial.println(("\nChose network number:"));
        odpoved.pridaj_cely(0);
        // -------------------Never gets past this one-------
        if ((odpoved.Nacislo10() >= 0) && (odpoved.Nacislo10() < sieti)) {
          Serial.printf(("Zadaj heslo pre %s\n"), WiFi.SSID(odpoved.Nacislo10()).c_str());
          String heslo = Serial.readString();
          Serial.print(F("Dostal som "));
          for (uint8_t i = 0; i > heslo.length(); i++) Serial.print(heslo[i]);
          Serial.println();
          Serial.printf(("Vybral som možnosť číslo %d a sieť: "), odpoved.Nacislo10(), WiFi.SSID(odpoved.Nacislo10()).c_str());
          //WiFi.begin(WiFi.SSID(odpoved.Nacislo10()).c_str(), heslo);
        } else Serial.printf(("Nesprávny výber %d"), odpoved.Nacislo10());
    }
  }
}

I have commented all the functions that use pins. The source compiles without any problem.
I am adding the result of exception decoder as it did not help me solve it.

Decoding stack results
0x40202a8d: __yield() at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/core_esp8266_main.cpp line 105
0x40202355: Stream::timedRead() at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/Stream.cpp line 37
0x40202392: Stream::readString() at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/Stream.cpp line 240
0x402013b6: pripojenie(bool) at /home/asi/Dropbox/Arduino/hotel_vstup/hotel_vstup.ino line 315
0x40203411: malloc(size_t) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/heap.cpp line 95
0x40204548: umm_malloc(size_t) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/umm_malloc/umm_malloc.cpp line 1685
0x402018d8: ESP8266WiFiScanClass::_scanDone(void*, int) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/libraries/ESP8266WiFi/src/ESP8266WiFiScan.cpp line 296
0x4020141c: pripojenie_samo(unsigned char) at /home/asi/Dropbox/Arduino/hotel_vstup/hotel_vstup.ino line 327
0x402018d8: ESP8266WiFiScanClass::_scanDone(void*, int) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/libraries/ESP8266WiFi/src/ESP8266WiFiScan.cpp line 296
0x40204bb1: std::_Function_handler ::_M_invoke(std::_Any_data const&, int) at /home/asi/.arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/2.5.0-3-20ed2b9/xtensa-lx106-elf/include/c++/4.8.2/functional line 2073
0x4020197c: ESP8266WiFiScanClass::_scanDone(void*, int) at /home/asi/.arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/2.5.0-3-20ed2b9/xtensa-lx106-elf/include/c++/4.8.2/functional line 2300
0x4020e5b8: sys_check_timeouts at core/timeouts.c line 368
0x40202957: loop_task(ETSEvent*) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/core_esp8266_main.cpp line 133
0x4020ac9a: __ssputs_r at /home/earle/src/esp-quick-toolchain/repo/newlib/newlib/libc/stdio/nano-vfprintf.c line 233
0x40206938: _printf_i at /home/earle/src/esp-quick-toolchain/repo/newlib/newlib/libc/stdio/nano-vfprintf_i.c line 194
0x4020ac9a: __ssputs_r at /home/earle/src/esp-quick-toolchain/repo/newlib/newlib/libc/stdio/nano-vfprintf.c line 233
0x402034b4: malloc_loc(size_t, char const*, int) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/heap.cpp line 126
0x40204548: umm_malloc(size_t) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/umm_malloc/umm_malloc.cpp line 1685
0x402018d8: ESP8266WiFiScanClass::_scanDone(void*, int) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/libraries/ESP8266WiFi/src/ESP8266WiFiScan.cpp line 296
0x402018d8: ESP8266WiFiScanClass::_scanDone(void*, int) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/libraries/ESP8266WiFi/src/ESP8266WiFiScan.cpp line 296
0x40204738: umm_realloc(void*, size_t) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/umm_malloc/umm_malloc.cpp line 1745
0x402018d8: ESP8266WiFiScanClass::_scanDone(void*, int) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/libraries/ESP8266WiFi/src/ESP8266WiFiScan.cpp line 296
0x4020299c: esp_yield() at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/core_esp8266_main.cpp line 91
0x40202f53: delay(unsigned long) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/core_esp8266_wiring.cpp line 54
0x40201a89: ESP8266WiFiScanClass::scanNetworks(bool, bool, unsigned char, unsigned char*) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/libraries/ESP8266WiFi/src/ESP8266WiFiScan.cpp line 98
0x40203942: uart_write(uart_t*, char const*, size_t) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/uart.cpp line 498
0x4020299c: esp_yield() at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/core_esp8266_main.cpp line 91
0x40202f53: delay(unsigned long) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/core_esp8266_wiring.cpp line 54
0x402015fd: loop() at /home/asi/Dropbox/Arduino/hotel_vstup/hotel_vstup.ino line 460
0x40201410: pripojenie_samo(unsigned char) at /home/asi/Dropbox/Arduino/hotel_vstup/hotel_vstup.ino line 325
0x40204bb8: std::_Function_base::_Base_manager ::_M_manager(std::_Any_data&, std::_Any_data const&, std::_Manager_operation) at /home/asi/.arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/2.5.0-3-20ed2b9/xtensa-lx106-elf/include/c++/4.8.2/functional line 1934
0x40204ba4: std::_Function_handler ::_M_invoke(std::_Any_data const&, int) at /home/asi/.arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/2.5.0-3-20ed2b9/xtensa-lx106-elf/include/c++/4.8.2/functional line 2069
0x40201e50: HardwareSerial::setDebugOutput(bool) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/HardwareSerial.cpp line 79
0x40202a4c: loop_wrapper() at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/core_esp8266_main.cpp line 125


line 325 is a wrapper function because async scan can only call void function of specific type and calls pripojenie_samo(uint8_t pointless)
Serial Output: (after translation to English)
Beginning connection routine
Search result 3
-----------------------------------------------------
-----------------------------------------------------
Found  3 networks

-----------------------------------------------------

0: VM5070527, Kanál:11 (-55dBm) 
1: Virgin Media, Kanál:11 (-74dBm) 
2: VM5076233, Kanál:11 (-85dBm) 
-----------------------------------------------------

Chose network number:
Instance cleared
one piece input read

Panic /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/core_esp8266_main.cpp:103 __yield

>>>stack>>>


 ets Jan  8 2013,rst cause:2, boot mode:(3,6)

load 0x4010f000, len 1384, room 16 
tail 8
chksum 0x2d
csum 0x2d
v8b899c12
~ld

SDK:2.2.1(cfd48f3)/Core:2.5.2=20502000/lwIP:STABLE-2_1_2_RELEASE/glue:1.1-7-g82abda3/BearSSL:a143020



user61851: I have figured it out
There seem to be understandable limitations if what kind of function can be run as a result of asynchronous scanning (which doesn't seem to interrupt running of a loop function)
So if I have used delay(x) or a while loop until there is input on serial, MCU resets after allotted time runs out.
I have re-written code to start function from loop when scan is complete, and it all runs fine now. 
I guess Arduino isn't right language for parallel programing

61851: <p>I am building a simple telnet style interface for experimental settings on my project. I am getting all the serial output sent to serial (and USB to PC). The code works fine, but if I try to read from Serial or check 'Serial.available()' I will get:</p>

<blockquote>
  <p>Fatal exception 9(LoadStoreAlignmentCause)</p>
</blockquote>

<p>Definition:
<code>bool pridaj_cely(uint8_t source_from=0, uint8_t line_LCD=0);</code></p>

<p>The code:</p>

<pre><code>bool Vstup::pridaj_cely(uint8_t source_from, uint8_t line_LCD) {
  uint8_t i = 0;
  Serial.println(F("one piece input read"));
  switch (origin) {
    case 0: { //Serial
        int16_t znak = -1;
        while (Serial.available() &lt; 0) {
          Serial.print(F("."));
          delay(100);
        }
        Serial.print(F("Somothing is comming"));
        while (Serial.available() &gt; 0) {
          celok[i] = Serial.read();
          if (i &lt; 12)  i++;
        }
      }
      break;
  }
  return 1;
}
</code></pre>

<p>Code of Priojenie:</p>

<pre><code>bool pripojenie(bool force_it = 0) {
  Serial.println(("Beginning connection routine"));
  kolo = millis();
  while (!WiFi.isConnected()) {
    int8_t sieti = WiFi.scanComplete();
    Serial.printf("Search result %X", sieti);
    switch (sieti) {
      case -2:
        Serial.println(("\tSearch begins"));
        WiFi.scanNetworks(1);
        delay(50);
        break;
      case -1:
        Serial.print(("."));
        delay(300);
        break;
      default: //This is the relevant case
        Vstup odpoved;
        Serial.ciara;
        Serial.ciara;
        Serial.printf(("Found %X networks"), sieti);
        Serial.ciara;
        Serial.println();
        for (uint8_t i = 0; i &lt; sieti; i++) {
          Serial.printf("%d: %s, Kanál:%d (%ddBm) %s\n", i, WiFi.SSID(i).c_str(), WiFi.channel(i), WiFi.RSSI(i), WiFi.encryptionType(i) == ENC_TYPE_NONE ? "Otvorena" : "");
        }
        Serial.ciara;
        Serial.println(("\nChose network number:"));
        odpoved.pridaj_cely(0);
        // -------------------Never gets past this one-------
        if ((odpoved.Nacislo10() &gt;= 0) &amp;&amp; (odpoved.Nacislo10() &lt; sieti)) {
          Serial.printf(("Zadaj heslo pre %s\n"), WiFi.SSID(odpoved.Nacislo10()).c_str());
          String heslo = Serial.readString();
          Serial.print(F("Dostal som "));
          for (uint8_t i = 0; i &gt; heslo.length(); i++) Serial.print(heslo[i]);
          Serial.println();
          Serial.printf(("Vybral som možnosť číslo %d a sieť: "), odpoved.Nacislo10(), WiFi.SSID(odpoved.Nacislo10()).c_str());
          //WiFi.begin(WiFi.SSID(odpoved.Nacislo10()).c_str(), heslo);
        } else Serial.printf(("Nesprávny výber %d"), odpoved.Nacislo10());
    }
  }
}
</code></pre>

<p>I have commented all the functions that use pins. The source compiles without any problem.</p>

<p>I am adding the result of exception decoder as it did not help me solve it.</p>

<pre><code>
Decoding stack results
0x40202a8d: __yield() at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/core_esp8266_main.cpp line 105
0x40202355: Stream::timedRead() at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/Stream.cpp line 37
0x40202392: Stream::readString() at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/Stream.cpp line 240
0x402013b6: pripojenie(bool) at /home/asi/Dropbox/Arduino/hotel_vstup/hotel_vstup.ino line 315
0x40203411: malloc(size_t) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/heap.cpp line 95
0x40204548: umm_malloc(size_t) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/umm_malloc/umm_malloc.cpp line 1685
0x402018d8: ESP8266WiFiScanClass::_scanDone(void*, int) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/libraries/ESP8266WiFi/src/ESP8266WiFiScan.cpp line 296
0x4020141c: pripojenie_samo(unsigned char) at /home/asi/Dropbox/Arduino/hotel_vstup/hotel_vstup.ino line 327
0x402018d8: ESP8266WiFiScanClass::_scanDone(void*, int) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/libraries/ESP8266WiFi/src/ESP8266WiFiScan.cpp line 296
0x40204bb1: std::_Function_handler ::_M_invoke(std::_Any_data const&amp;, int) at /home/asi/.arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/2.5.0-3-20ed2b9/xtensa-lx106-elf/include/c++/4.8.2/functional line 2073
0x4020197c: ESP8266WiFiScanClass::_scanDone(void*, int) at /home/asi/.arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/2.5.0-3-20ed2b9/xtensa-lx106-elf/include/c++/4.8.2/functional line 2300
0x4020e5b8: sys_check_timeouts at core/timeouts.c line 368
0x40202957: loop_task(ETSEvent*) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/core_esp8266_main.cpp line 133
0x4020ac9a: __ssputs_r at /home/earle/src/esp-quick-toolchain/repo/newlib/newlib/libc/stdio/nano-vfprintf.c line 233
0x40206938: _printf_i at /home/earle/src/esp-quick-toolchain/repo/newlib/newlib/libc/stdio/nano-vfprintf_i.c line 194
0x4020ac9a: __ssputs_r at /home/earle/src/esp-quick-toolchain/repo/newlib/newlib/libc/stdio/nano-vfprintf.c line 233
0x402034b4: malloc_loc(size_t, char const*, int) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/heap.cpp line 126
0x40204548: umm_malloc(size_t) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/umm_malloc/umm_malloc.cpp line 1685
0x402018d8: ESP8266WiFiScanClass::_scanDone(void*, int) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/libraries/ESP8266WiFi/src/ESP8266WiFiScan.cpp line 296
0x402018d8: ESP8266WiFiScanClass::_scanDone(void*, int) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/libraries/ESP8266WiFi/src/ESP8266WiFiScan.cpp line 296
0x40204738: umm_realloc(void*, size_t) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/umm_malloc/umm_malloc.cpp line 1745
0x402018d8: ESP8266WiFiScanClass::_scanDone(void*, int) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/libraries/ESP8266WiFi/src/ESP8266WiFiScan.cpp line 296
0x4020299c: esp_yield() at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/core_esp8266_main.cpp line 91
0x40202f53: delay(unsigned long) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/core_esp8266_wiring.cpp line 54
0x40201a89: ESP8266WiFiScanClass::scanNetworks(bool, bool, unsigned char, unsigned char*) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/libraries/ESP8266WiFi/src/ESP8266WiFiScan.cpp line 98
0x40203942: uart_write(uart_t*, char const*, size_t) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/uart.cpp line 498
0x4020299c: esp_yield() at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/core_esp8266_main.cpp line 91
0x40202f53: delay(unsigned long) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/core_esp8266_wiring.cpp line 54
0x402015fd: loop() at /home/asi/Dropbox/Arduino/hotel_vstup/hotel_vstup.ino line 460
0x40201410: pripojenie_samo(unsigned char) at /home/asi/Dropbox/Arduino/hotel_vstup/hotel_vstup.ino line 325
0x40204bb8: std::_Function_base::_Base_manager ::_M_manager(std::_Any_data&amp;, std::_Any_data const&amp;, std::_Manager_operation) at /home/asi/.arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/2.5.0-3-20ed2b9/xtensa-lx106-elf/include/c++/4.8.2/functional line 1934
0x40204ba4: std::_Function_handler ::_M_invoke(std::_Any_data const&amp;, int) at /home/asi/.arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/2.5.0-3-20ed2b9/xtensa-lx106-elf/include/c++/4.8.2/functional line 2069
0x40201e50: HardwareSerial::setDebugOutput(bool) at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/HardwareSerial.cpp line 79
0x40202a4c: loop_wrapper() at /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/core_esp8266_main.cpp line 125

</code></pre>

<p>line 325 is a wrapper function because async scan can only call void function of specific type and calls pripojenie_samo(uint8_t pointless)</p>

<p>Serial Output: (after translation to English)</p>

<pre><code>Beginning connection routine
Search result 3
-----------------------------------------------------
-----------------------------------------------------
Found  3 networks

-----------------------------------------------------

0: VM5070527, Kanál:11 (-55dBm) 
1: Virgin Media, Kanál:11 (-74dBm) 
2: VM5076233, Kanál:11 (-85dBm) 
-----------------------------------------------------

Chose network number:
Instance cleared
one piece input read

Panic /home/asi/.arduino15/packages/esp8266/hardware/esp8266/2.5.2/cores/esp8266/core_esp8266_main.cpp:103 __yield

&gt;&gt;&gt;stack&gt;&gt;&gt;
</code></pre>

<pre><code>
 ets Jan  8 2013,rst cause:2, boot mode:(3,6)

load 0x4010f000, len 1384, room 16 
tail 8
chksum 0x2d
csum 0x2d
v8b899c12
~ld

SDK:2.2.1(cfd48f3)/Core:2.5.2=20502000/lwIP:STABLE-2_1_2_RELEASE/glue:1.1-7-g82abda3/BearSSL:a143020

</code></pre>
 61851: <p>I have figured it out
There seem to be understandable limitations if what kind of function can be run as a result of asynchronous scanning (which doesn't seem to interrupt running of a loop function)
So if I have used <code>delay(x)</code> or a while loop until there is input on serial, MCU resets after allotted time runs out.
I have re-written code to start function from loop when scan is complete, and it all runs fine now. 
I guess Arduino isn't right language for parallel programing</p>
