Radarcape:Watchdog

The tasks described in this manual require advanced knowledge of Unix/Linux.

Hardware Watchdog Overview

Starting with the 2nd production Batch, the Radarcape is equipped with a MAX6371 hardware watchdog. The hardware watchdog shall ensure that the Radarcape recovers if the system software hangs. This is especially important if the Radarcape is operated at remote locations.

The watchdog listens on GIPO_60 of the BeagleBone board for a toggling signal. If no toggling of the port happend, the BeagleBone board is being reset via the SYS_RESET pin. Therefore, GIPO_60 must be toggled by software at least once every minute otherwise the Radarcape reboots. Toggling of GIPO_60 is usually being done by the Radarcape daemon (rcd).

Manual Hardware Watchdog Toggling

In several circumstances it becomes necessary to temporarily stop or de-install the Radarcape daemon. It becomes necessary to toggle GIPO_60 to hinder the hardware watchdog rebooting the Radarcape. This can be achived using the following commands:

echo *** Configure Watchdog retrigger pin & toggle first time
echo 07 > /sys/kernel/debug/omap_mux/gpmc_ben1
echo 60 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio60/direction
echo 1 > /sys/class/gpio/gpio60/value
echo 0 > /sys/class/gpio/gpio60/value

A single line retrigger command looks like:

while :; do echo 1 > /sys/class/gpio/gpio60/value; echo 0 > /sys/class/gpio/gpio60/value; echo 'Hit CTRL+C'; sleep 30; done