System calls

Reset reason

Since 0.6.0:

The system can track the hardware and software resets of the device.

// EXAMPLE
// Restart in safe mode if the device previously reset due to a PANIC (SOS code)
void setup() {
   System.enableFeature(FEATURE_RESET_INFO);
   if (System.resetReason() == RESET_REASON_PANIC) {
       System.enterSafeMode();
   }
}

You can also pass in your own data as part of an application-initiated reset:

// EXAMPLE

void setup() {
    System.enableFeature(FEATURE_RESET_INFO);

    // Reset the device 3 times in a row
    if (System.resetReason() == RESET_REASON_USER) {
        uint32_t data = System.resetReasonData();
        if (data < 3) {
            System.reset(data + 1);
        }
    } else {
        // This will set the reset reason to RESET_REASON_USER
        System.reset(1);
    }
}

Note: This functionality requires FEATURE_RESET_INFO flag to be enabled in order to work.

resetReason() - System

System.resetReason()

Returns a code describing reason of the last device reset. The following codes are defined:

This is also uploaded to the cloud using the last_reset event after reconnecting to the cloud.

On devices with an external hardware watchdog, including the Tracker One, Monitor One, Tracker SoM, and Muon, the RESET_REASON_WATCHDOG is not used. The reset reason will either be RESET_REASON_PIN_RESET or RESET_REASON_POWER_MANAGEMENT.

Not all reset reasons are supported on all MCUs.

Gen 3 Devices (nRF52) (B-Series SoM, Tracker SoM, Tracker One, Boron, Argon, and E404X):

Gen 4 Devices (RTL872x) (P2, Photon 2, and M-SoM):

resetReasonData() - System

System.resetReasonData()

Returns a user-defined value that has been previously specified for the System.reset() call.

If the reason is RESET_REASON_PANIC, then the reasonReasonData() is the panic code. For more information on the meaning of these codes, see red blink SOS.

reset() - System

reset(uint32_t data)

This overloaded method accepts an arbitrary 32-bit value, stores it to the backup register and resets the device. The value can be retrieved via resetReasonData() method after the device has restarted.