Picture Frame - a RPiPF on the schedule

The previous builds were smaller but smarter. They actually turned off when nobody was around to see. The RPiPF (RapsberyPi Picture Frame) is not there yet.

A small step forward: turn off when nobody's around to watch and turn on when there may be - on the schedule. Turn on at 7am, turn off 11pm.

To control the TV from RPI - CEC

Consumer Electronics Control (CEC) is a control channel over the HDMI cable.

Install cec-utils

sudo apt-get install cec-utils

Turn the TV off:

echo "standby 0" | cec-client -s -d 1 

Turn the TV on

echo "on 0" | cec-client -s -d 1


Don't mind the CLI plumbing - these command are like magic: '-s' means execute single command while '-d 1' limits the damage to you eyes by cutting down the logging spewed back at ya. Note that the echo just pipes the actual command to the cec-client - an interactive program by birth.

Flying on a Magic Script

The ph.sh script that was previously used to just start feh. Now it does the scheduling.

The script loops and:

• checks the time
• decides if the slide show should or should not be running
• depending on that decision either 
• kills feh and turns off the TV or 
• starts feh and turns on the TV
• sleeps for 1 minute and repeats

logger "PF started"
PATH=$HOME/bin:$PATH
while true; do
  now=`date +%H%M`
  fehpid=`pidof feh`
  if [ $now -gt 700 ] && [ $now -lt 2300 ]; then
    if [ -z $fehpid ]; then
      logger "PF now=$now fehpid=$fehpid ON"
      tvon
      gofeh &
    fi
  else
    if [ ! -z $fehpid ]; then
      logger "PF now=$now fehpid=$fehpid OFF"
      skill feh
      tvoff
    fi
  fi
  sleep 1m 
done

Taking it apart

• The lines with 'logger ...' just put entries in /var/log/user.log so I know what was happening.
• The line "PATH=" just adds /home/pi/bin (user's pi bin directory) to the path. Normally this should be done the .profile.
• Then we loop forever...
• The line 'now=... ' captures current time into the 'now' variable. The time is formatted as hhmm (in 24 hour format) for easier comparing later.
• The 'fehpid=...'  captures the process ID of feh, the slide show process. If it is not running, the fehpid is empty string.
• Then in the first 'if' the script compares the $now to fit between 700 and 2300, military style.
• And finally, the nested 'ifs' decide to turn on the show or to stop it. The '-z' checks for empty, while the '! -z' checks for not empty.
• The small command scripts:  tvon, tvoff, gofeh got created in ~/bin (and chmod +x them so they can be executed).
• The gofeh is run in the background (with '&') so the script can continue monitoring the time after starting the slide show.

References

CEC on Pi