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When the system restarts, the system registers contain the reason for the restart at boot time in a board specific manner. This API provides a generic method of fetching the reason for the restart.

You can use the ResetReason interface to determine the cause of the last system reset in a portable fashion.

ResetReason class reference

Static Public Member Functions
static reset_reason_t get ()
 Get the platform independent reason code for the last system reset. More...
static uint32_t get_raw ()
 Get the platform specific reason code for the last system reset. More...

ResetReason example

Check the cause of the last system reset:

#include "mbed.h"
#include "ResetReason.h"

#include <string>

std::string reset_reason_to_string(const reset_reason_t reason)
    switch (reason) {
            return "Power On";
            return "Hardware Pin";
            return "Software Reset";
            return "Watchdog";
            return "Other Reason";

int main()
    const reset_reason_t reason = ResetReason::get();

    printf("Last system reset reason: %s\r\n", reset_reason_to_string(reason).c_str());
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