[peterson]

The alarm seems to work very well. Still some minor parts I am unsure about, but it definitely works. Below is a shell function that will wait for a given amount of time. Last night I set my weather screensaver script to run in 30 minute intervals, and it did.

According to the log I created and the accompanying dmesg output, the device woke up every 30 minutes, downloaded the latest weather report, and then went back to sleep 90 seconds after that.

# the RTC to use
RTC=0

OUTPUTFILE=/tmp/alarmlogger

# sets an RTC alarm
# arguments: $1 - time in seconds from now

wait_for () {
        TS=`date +%s` 
        TS=$(($TS + $1))
        echo "Setting alarm to $TS ($1 seconds in the future)" >>$OUTPUTFILE

        echo 0 > /sys/class/rtc/rtc$RTC/wakealarm
        echo $TS > /sys/class/rtc/rtc$RTC/wakealarm

        if test $TS -ne `cat /sys/class/rtc/rtc$RTC/wakealarm`; then
                echo "Failure setting alarm on rtc$RTC, wanted $TS, got `cat /sys/class/rtc/rtc$RTC/wakealarm`" >>$OUTPUTFILE
        else
                echo "Success on rtc$RTC" >>$OUTPUTFILE

                # wait for the alarm to end
                while test 1 -eq 1; do
                        if test 0 -eq $((`cat /sys/class/rtc/rtc$RTC/wakealarm`)); then
                                break;
                        elif test `date +%s` -gt $((`cat /sys/class/rtc/rtc$RTC/wakealarm`)); then
                                break;
                        else
                                sleep 1
                        fi
                done
        fi

        # not sure whether this is required
        lipc-set-prop com.lab126.powerd -i deferSuspend 1
}