watchdog 5.15-2 (armhf binary) in ubuntu zesty

 The watchdog program writes to /dev/watchdog every ten seconds. If
 the device is opened but not written to within a minute, the machine
 will reboot. This feature is available when the kernel is built with
 "software watchdog" support (standard in Debian kernels) or if the
 machine is equipped with a hardware watchdog (in which case this
 package can also be used to "pet" it, resetting its timer).
 .
 The kernel software watchdog's ability to reboot will depend on the
 state of the machine and interrupts.
 .
 The watchdog tool itself runs several health checks and acts
 appropriately if the system is not in good shape.