What does the number in “Reboot reason: 0x13” refer to?
The source code of the firmware shows:
RESET_REASON_NONE = 0x00000000,
RESET_REASON_POWERON = 0x00000003,
RESET_REASON_BROWNOUT = 0x00000002,
RESET_REASON_WDT_TIMEOUT = 0x00000010,
RESET_REASON_DMT_TIMEOUT = 0x00000020,
RESET_REASON_SOFTWARE = 0x00000040,
RESET_REASON_MCLR = 0x00000080,
RESET_REASON_CONFIG_MISMATCH = 0x00000200,
RESET_REASON_ALL = 0x000002F3
As the method to clear the reason is documented as as:
This function clears the specified status flag(s) that were previously set by the processor to identify the reason for the most recent reset.
… and RESET_REASON_ALL = 0x2F3 is just the bitwise OR of all the above, a first guess is that 0x13 refers to both 0x03 and 0x10. But that needs to be confirmed.
WDT would be a watchdog timer; DMT a deadman timer.