Building a Wi-Fi Router Watchdog

Dev created a watchdog for a Wi-Fi extender using a Raspberry Pi Pico. This monitors Wi-Fi connectivity for his smart home lighting system, which would require a reset twice a year due to rapid power interruptions.

- Dev Gualtieri

My smart home lighting system has been operational for more than two years. The system uses a supervisory program installed on a Raspberry Pi computer to control the commonly available Kasa smart plugs, wall switches and dimmer modules in a Wi-Fi network. This smart home program on the Raspberry Pi has been robust against power failures, rebooting into the proper state when power returns. Unfortunately, the Wi-Fi extender I use hangs about twice each year, requiring a manual reset.

I had no idea what could cause this problem until a chance occurrence. While working at my desktop computer, I heard a rapid tick-tick from its uninterruptible power supply (UPS). This must have been caused by the power company doing a rapid switching between its circuits. The resulting brief power interruption was too rapid to affect the several digital clocks in my house, including the one at my microwave oven, and it was too rapid to trigger a reboot of the smart home Raspberry Pi. When I checked the status of the smart home Wi-Fi extender, I found that it had hung and did not respond. Now, I had at least one cause for lapses in my smart home Wi-Fi connectivity, and I needed a solution.

Several years ago, I wanted to buy a timer for the exposure station I use for photosensitive printed circuit boards. The customer comments for these devices showed that a common use was a daily power off-on cycle of routers to correct the same problem.

This tactic was used by people who need constant access to the video cameras at their remote vacation homes. While effective, this is not an elegant solution, and it would potentially result in a long outage if the router hung just after the power cycle.