Patting the Dog
A watchdog timer is a great way of improving reliability for little cost in small, inexpensive computers such as the Raspberry Pi and Arduino.
Making your projects more reliable
Lead Image © Oleksiy Tsupe, 123RF.com
Computers sometimes lose their way. A power glitch, RFI (radio frequency interference), hanging peripherals, or just plain bad programming can make your small computer hang, causing your applications to fail. It happens all the time. For example, how often do you have to reboot your PC? Not very often, perhaps, but once in while your Mac or PC will freeze requiring you to cycle the computer's power.
Raspberry Pis will sometimes freeze because a task does not free up sockets or consumes other system resources. Arduinos will sometimes freeze because of brownouts on the power line or a short power interruption. They might also freeze because they run out of system resources such as RAM, stack space, or both, which are very limited resources in an Arduino. Sometimes even programmers make mistakes.
With small computers, you can give your device a chance to recover from faults by using what is called a watchdog timer (WDT). A WDT is an electronic timer used to detect and recover from computer malfunctions (Figure 1).
[...]
Use Express-Checkout link below to read the full article (PDF).
Buy this article as PDF
Express-Checkout as PDF
Pages: 8
Price $2.95
(incl. VAT)
(incl. VAT)
Buy Raspberry Pi Geek
TABLET & SMARTPHONE APPS
US / Canada
UK / Australia
Related content
-
Managing solar power systems with SunAir boards
A successful solar power project requires data analysis and the ability to modify the system to take advantage of prevailing weather conditions.
-
SunRover part 1: Track motor controller/power system
Take your first steps in building a solar-powered robot.
-
Protect your electronics from lightning strikes
Add a lightning detector to your vulnerable projects via the I2C bus to protect them from electrical storms.
-
Sending your data through the air
Build a low-powered wireless system for your outdoor weather station using inexpensive hardware.
-
Understanding your data with graphs
One picture is worth a thousand words … or table columns … so learn how to create graphs on your Raspberry Pi and display them on your tablet or smartphone.
