diff --git a/README.txt b/README.txt
index dbc882b..8176f0b 100644
--- a/README.txt
+++ b/README.txt
@@ -70,6 +70,10 @@ sudo sed -i 's/#\(watchdog-device\)/\1/
 
 sudo service watchdog start
 
+Note: projectionscreen.sh is a standalone program called remotely by pidor
+because pidor knows the IP adress of the projector but doorbuzz has the RF remote connected.
+The remote command works with ssh, so install pidor's root pub key into
+~pi/.ssh/authorized_keys
 todo
 ====
 create a config file
diff --git a/projectionscreen.sh b/projectionscreen.sh
new file mode 100755
index 0000000..9f7c3bc
--- /dev/null
+++ b/projectionscreen.sh
@@ -0,0 +1,31 @@
+STOPBUTTON=8
+UPBUTTON=7
+DOWNBUTTON=23
+gpio -g mode $STOPBUTTON out
+gpio -g mode $UPBUTTON out
+gpio -g mode $DOWNBUTTON out
+function rollstop() {
+gpio -g write $STOPBUTTON 1
+sleep 0.2
+gpio -g write $STOPBUTTON 0
+}
+function rollup() {
+gpio -g write $UPBUTTON 1
+sleep 0.2
+gpio -g write $UPBUTTON 0
+}
+function rolldown() {
+gpio -g write $DOWNBUTTON 1
+sleep 0.2
+gpio -g write $DOWNBUTTON 0
+}
+
+logger "$0 action $1"
+case "$1" in
+  up) rollup
+      ;;
+  down) rolldown
+      ;;
+  stop) rollstop
+      ;;
+esac