Arduino Watchdog Timer

The watchdog timer will automatically cut power if the watchdog app running on the PC fails to send keepalives. This protects against the monitoring PC failing for some reason. Without the PC present to monitor the mount position the watchdog will automatically cut power to the mount to prevent it tracking past safe limits.

Parts List

ItemSourceApprox. CostNotes
Arduino Uno$5.50
4-Channel Relay Module DC 5V For Arduinoebay$6.00
9VDC power supply for Arduinoebay$6.00
on-off toggle switchebay$5.00
Arduino jumper wires M-F
Wires and connectors for mount power cableI used Anderson Powerpole connectors and 18 AWG wire.
EnclosureI used a PVC electrical junction box


The Arduino program is here.

Make sure to use the NO (Normally Open) terminal of the relay so that the mount does not receive power until the watchdog is activated.

After connecting everything together and testing it, secure the Arduino and the Relay module in an enclosure. I used an ordinary PVC electrical junction box from the local home improvement store. The toggle switch is available in case there is ever a need to bypass the watchdog timer.

Andy Galasso 5/2015