I'm writing a program for
I'm trying to add logs, which will be saved in fatfs.
After some logs I get:
21:54:21.306 -> Debug exception reason: Stack canary watchpoint triggered (main) 21:54:21.306 -> Register dump: 21:54:21.306 -> PC : 0x40089827 PS : 0x00060b36 A0 : 0x40082179 A1 : 0x3ffd3860 21:54:21.340 -> A2 : 0x3ff40000 A3 : 0x00000033 A4 : 0x00000033 A5 : 0x00000000 21:54:21.340 -> A6 : 0x00000024 A7 : 0xff000000 A8 : 0xe37fc000 A9 : 0x0000007e 21:54:21.340 -> A10 : 0x00000000 A11 : 0xffffffff A12 : 0x00000004 A13 : 0x00000001 21:54:21.340 -> A14 : 0x00000005 A15 : 0x00000000 SAR : 0x00000004 EXCCAUSE: 0x00000001 21:54:21.340 -> EXCVADDR: 0x00000000 LBEG : 0x400014fd LEND : 0x4000150d LCOUNT : 0xfffffff6
Why does it happen to main?
This is quite likely caused by a stack overflow in your FreeRTOS task.
Increase the stack depth
The first thing I would do is increase the depth of the stack for your FreeRTOS task. E.g., if you created your task with a stack size of
configMINIMAL_STACK_SIZE, this might be as low as 768 bytes - which is not adequate for a lot of common requirements.
How much to increase the stack depth by?
It is not easy to answer this, but - in this case - it may be adequate to simply increase it until you no longer have stack overflows. If you are concerned about not needlessly wasting memory, FreeRTOS includes a mechanism to let you know how close a task has come to overflowing its stack.
A canary is just a marker at the end of a buffer - which is checked periodically. If it is changed from its default value, it means that the program has attempted to write beyond the end of the buffer - i.e. there has been a buffer overflow.
Detection of stack overflow using canaries is enabled in ESP IDF by changing two options in configuration (under
Component Config ->
If you disable the second option, you will instead get a Guru Meditation error - a
LoadProhibited exception - in the case of a stack overflow.
xTaskCreate()and stack depth
Bear in mind that the version of
xTaskCreate() in the ESP IDF differs from that in the original FreeRTOS. In the original FreeRTOS, the stack depth is specified in words. In the ESP IDF, it's specified in bytes. A very important distinction!
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