ESP8266 Unexpected Crash or Reset

[AffordableTech]

I had problems with the ESP8266 Gateway crashing and resetting every few minutes with an "Exception(28)".

After lots of searching, I found it was a problem in the 'core driver' in the MySensors library (1.51).

The Fix:

• Open the "MyMessage.cpp" file in your "...\Arduino\libraries\MySensors" folder.
• Search for the "MyMessage& MyMessage::set(const char* value)" function (WARNING: there are several similar names).
• Comment the existing code out and add replacement as illustrated below.

/*  COMMENT OUT THE OLD FUNCTION
MyMessage& MyMessage::set(const char* value) {
	uint8_t length = min(strlen(value), MAX_PAYLOAD);
	miSetLength(length);
	miSetPayloadType(P_STRING);
	strncpy(data, value, length);
	return *this;
}
*/

/*   INSERT THE FOLLOWING IN ITS PLACE   */
MyMessage& MyMessage::set(const char* value) {
	uint8_t length = value == NULL ? 0 : min(strlen(value), MAX_PAYLOAD);
	miSetLength(length);
	miSetPayloadType(P_STRING);
	if (length) {		
		strncpy(data, value, length);
	}
	// null terminate string
	data[length] = 0;
	return *this;
}

If you compile any MySensors ESP8266 project, the library will be rebuilt and with a bit of luck the crashes will vanish.

Paul

[Yveaux]

@AffordableTech So, concluding, the set-method will crash when called with a null-pointer.
Does your sketch call it with a null-pointer, or does the MySensors library pass it somewhere along the road?

[AffordableTech]

@Yveaux

Yes, I believe it happens when a client connects with no message, it causes a memory fault (loss); after several such connections the stack is exhausted and the ESP8266 crashes (and reboots).

This cured my crashes, but I'm sure there are many other possibilities for an Exception(28).

[hek]

This has been fixed in development branch. It was never backported.

[AffordableTech]

@hek

Yes, as I gathered, but I have too many sensors on 1.5.1 and don't want to upgrade them to 2.0 while its not an official release.

I posted it because there are probably others on 1.5.1 with the problem, but can't find a fix.

Cheers...