Radarcape:Watchdog

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

Hardware Watchdog Retriggering

Starting with the 2nd production batch of the Radarcape, there is an external hardware watchdog foreseen. Due to the nature of the device, running 24/7 at various environmental conditions and remote locations, this extra safety is pretty useful. A MAX6371 device is beeing used for this, which needs to be retriggered once every minute on GPIO1_18. The first retrigger activity shall happen in the cape.sh shell skript as below, afterwards toggling GPIO1_18 should be done in the Linux application SW.

It is expected that this retriggering is done in the Linux application software, but for testing it might be useful having a small command line retrigger:

Linux 3.2 Versions

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