Patch to prevent Reboot loop when using watchdog #16
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When resetting with the watchdog on AVR micros, the watchdog remains enabled after the reset, but with a very short 15ms timeout. With the default bootloader, that creates a situation where the arduino constantly resets itself until physically powered off. The patch adds the ability to use the ISR to perform a "soft" reset that will disable the watchdog before resetting. The patch behaves as expected when using the sleep function. Since this is a AVR only problem, nothing is changed for other architectures. To enable the soft reset, use a negative number in the Watchdog.enable function. Watchdog.enable(4000); // This uses the hard reset but might hang on some boards (depending on the bootloader) Watchdog.enable(-4000); // This will never hang and uses the soft reset
Corrects a bug if sleep was exited by another interrupt (the sleep timer interrupt would later reset the AVR when it times out)
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When resetting with the watchdog on AVR micros, the watchdog remains enabled after the reset, but with a very short 15ms timeout.
With the default bootloader, that creates a situation where the arduino constantly resets itself until physically powered off.
Here is a description of the problem:
https://github.com/arduino/Arduino/issues/4492
https://arduino.stackexchange.com/questions/2922/watchdog-timer-stuck-in-restart-loop-green-led-flashing/45281#45281
The patch adds the ability to use the ISR to perform a "soft" reset that will disable the watchdog before resetting. It solves the issue without having to reflash the bootloader with WATCHDOG_MODS
The patch behaves as expected when using the sleep function (even when exiting sleep by another interrupt).
To enable the soft reset, use a negative number in the Watchdog.enable function.
Watchdog.enable(4000); // This uses the hard reset but will hang in a boot loop on some boards (depending on the bootloader)
Watchdog.enable(-4000); // This will never hang and uses the soft reset
(adding an optional softReset parameter to Watchdog.enable could be a cleaner way to do it)
The BasicUsage.ino example can be modified as shown to prevent endless reset on arduinos with a bootloader that does not disable the watchdog.