I’m having trouble with my ESP32-S2 sometimes (seemingly randomly?) crashing when sending a large websocket.

The crash log outputted on serial:

Guru Meditation Error: Core  0 panic'ed (LoadProhibited). Exception was unhandled.

Core  0 register dump:
PC      : 0x40087297  PS      : 0x00060830  A0      : 0x80087bc9  A1      : 0x3ffd2560  
A2      : 0x3ffc655c  A3      : 0x3ffe3610  A4      : 0x3ffcbd54  A5      : 0x3ffc65d8
A6      : 0x3f4c0058  A7      : 0x00000001  A8      : 0xa941d536  A9      : 0x3ffd2540  
A10     : 0x3ffe3610  A11     : 0x3ffe3610  A12     : 0x3ffe35f0  A13     : 0x00000000
A14     : 0x3ffcd288  A15     : 0x3ffcd23c  SAR     : 0x00000013  EXCCAUSE: 0x0000001c  
EXCVADDR: 0xa941d542  LBEG    : 0x3ffe35f0  LEND    : 0x00000000  LCOUNT  : 0x40028358


Backtrace:0x40087294:0x3ffd25600x40087bc6:0x3ffd2590 0x40087bdf:0x3ffd25b0 0x40087bed:0x3ffd25d0 0x40083d30:0x3ffd25f0 0x40083d4f:0x3ffd2610 0x401015dd:0x3ffd2630 0x4008dc95:0x3ffd2650 0x40083366:0x3ffd2670 0x400918a1:0x3ffd2690 

  #0  0x40087294:0x3ffd2560 in AsyncWebSocket::_cleanBuffers() at .pio/libdeps/esp32-s2-saola-1/ESP Async WebServer/src/AsyncWebSocket.cpp:1224 (discriminator 3)
  #1  0x40087bc6:0x3ffd2590 in AsyncWebSocket::binaryAll(AsyncWebSocketMessageBuffer*) at .pio/libdeps/esp32-s2-saola-1/ESP Async WebServer/src/AsyncWebSocket.cpp:986
  #2  0x40087bdf:0x3ffd25b0 in AsyncWebSocket::binaryAll(char const*, unsigned int) at .pio/libdeps/esp32-s2-saola-1/ESP Async WebServer/src/AsyncWebSocket.cpp:974
  #3  0x40087bed:0x3ffd25d0 in AsyncWebSocket::binaryAll(unsigned char*, unsigned int) at .pio/libdeps/esp32-s2-saola-1/ESP Async WebServer/src/AsyncWebSocket.cpp:1133
  #4  0x40083d30:0x3ffd25f0 in sendMeasurements_Bin() at src/websockets.cpp:71
  #5  0x40083d4f:0x3ffd2610 in captureMeasurements() at src/websockets.cpp:49
  #6  0x401015dd:0x3ffd2630 in std::_Function_handler<void (), void (*)()>::_M_invoke(std::_Any_data const&) at c:usersvojta.platformiopackagestoolchain-xtensa-esp32s2xtensa-esp32s2-elfincludec++8.4.0bits/std_function.h:297
  #7  0x4008dc95:0x3ffd2650 in std::function<void ()>::operator()() const at c:usersvojta.platformiopackagestoolchain-xtensa-esp32s2xtensa-esp32s2-elfincludec++8.4.0bits/std_function.h:687
      (inlined by) Ticker::update() at .pio/libdeps/esp32-s2-saola-1/Ticker/Ticker.cpp:72
  #8  0x40083366:0x3ffd2670 in loop() at src/main.cpp:134
  #9  0x400918a1:0x3ffd2690 in loopTask(void*) at C:/Users/vojta/.platformio/packages/framework-arduinoespressif32/cores/esp32/main.cpp:50




ELF file SHA256: 0000000000000000

The function that periodically sends the websockets:

void sendMeasurements_Bin(){
  Serial.print("sending----");
  ws.binaryAll((uint8_t*)buffer, sizeof(buffer));
  Serial.println("sent");
  return ;

}

Where buffer is an array of structs:

struct __attribute__((packed)) Measurement {
    int16_t current_L;
    int16_t current_R;
    int16_t current_Total;
    int16_t setpoint;
    int16_t error;
    uint32_t encoder_L;
    uint32_t encoder_R;
    uint32_t timestamp; // Store the time when the measurement was taken
};

const int BUFFER_SIZE = 100;

Measurement buffer[BUFFER_SIZE];

Do you know what could be causing this issue? My guess is it’s something memory related but that doesn’t make sense to me as there’s no new memory being allocated, the buffer is initialized only once and then its rewritten and sent.

I tried printing out free heap size every time the data is sent, using:

Serial.print(esp_get_free_heap_size());

The free heap size doesn’t change very much, which is expected.