PPS status indication via LED for UP board

[hitimo]

One-liner that turns on green LED on UP board if clock error is below 999ns. Maybe useful for someone. (Related to https://github.com/ethz-asl/ethz_piksi_ros/wiki/Piksi-PPS-Sync)

while true; do var=$(chronyc sources -v | grep PPS0 | sed 's/.*+\/- \(.*\)ns/\1/'); var_low=0; var_high=999; if [ $var -gt $var_low -a $var -lt $var_high ]; then echo 1 > /sys/class/leds/upboard\:green\:/brightness; else echo 0 > /sys/class/leds/upboard\:green\:/brightness; fi; sleep 1; done

[rikba]

Thank you! I added it to the wiki.