Toggle the WDT input too slowly, too fast, or not at all, and a timeout will occur. Since a crashed program will likely speed up or bog down if it does anything at all, errant strobing of the tickle bit will almost certainly be outside the time band required. Even if wandering code issues output instructions their potentially scrambled little brains will be straightened out. In other words, a healthy dose of paranoia leads to better systems. It's fun to watch a multitasking product crash - the entire system might be hung, but one task still responds to interrupts.
Great Watchdog Timers For Embedded Systems, by Jack Ganssle . Maybe a pacemaker needs to reboot in a heartbeat (so to speak) or maybe backup. Jack Ganssle believes that embedded development can be much more efficient than it The 's built-in watchdog timer hardware was not used, over the . needs to reboot in a heartbeat (so to speak) or maybe backup hardware should. Parameter Backup Prior to Watchdog System Reset Jack Ganssle.
The Enhanced Watchdog Timer (WDT) runs independent of the rest of the system.
Design the logic so the jumper disconnects the WDT from the reset line possibly though an inverter so an inserted jumper sets debug mode.
Video: Jack ganssle watchdog backup EEVblog #818 - Embedded Electronics With Jack Ganssle
November 24, Stephen Evanczuk. The responses were varied, ranging from "Freak! Either handle these competently or initiate a WDT timeout.
This tells the story of a failed Clementine spacecraft mission that could have been saved by a watchdog, and elaborates on the design and implementation of watchdog techniques.
Watchdog timers are an often overlooked feature of microcontrollers. They function In this oldie-but-goodie, [Jack Ganssle] provides us with a great write up on watchdog timers. This tells the In such cases, some kind of backup is needed.
But it does offer a very intriguing feature. Surely the customers were irritated, and the possible future sales of that company at least somewhat diminished.
Pure software implementations are simply not reliable. Not surprisingly, the software team wished they had indeed used the watchdog timer, and had not implemented the thruster timeout in firmware.
It's external to the CPU, shares no resources, and is utterly simple, thus devoid of latent defects. The WDT cannot be disabled once enabled -- good thinking, folks! A watchdog that runs once a second will miss tasks that start only hourly.