118 turn off camera

README.md

@@ -367,6 +367,40 @@ When date reads correctly run
     sudo hwclock -w
     sudo hwclock -r
     sudo reboot
+## Setting up Systemd Services
+
+Dencam (Cyclops ONLY) uses a systemd service to turn on/off the PTZ 
+camera based on time of day. The camera is turned on for daytime and 
+astronomical twilight and turned off during nighttime. This script is
+is located at `dencam/utilities/camera_relay.py.`
+
+To set up this script to run as a systemd service, navigate to: 
+
+    cd /etc/systemd/system
+
+Create a new file: 
+
+    sudo nano camera_relay.service
+
+Insert the following: 
+
+    [Unit]
+    Description=Camera Relay
+
+    [Service]
+    Type=exec
+    ExecStart=/home/<User>/.virtualenvs/dencam/bin/python3 -u /home/<User>/dencam/utilities/camera_relay.py
+
+    [Install]
+    Wantedby=multi-user.target
+
+After saving the file, run:
+
+    sudo systemctl start camera_relay.service
+
+If the service needs to be stopped, run:
+
+    sudo systemctl stop camera_relay.service
 
 # Dencam Pages
 

utilities/camera_relay.py

@@ -0,0 +1,43 @@
+'''
+Use sun altitude to trigger camera relay and turn
+off camera when dark. Camera will stay on during
+daylight and astonomical twilight.
+
+To be used as a systemd service.
+'''
+
+import time
+from datetime import datetime
+from RPi import GPIO
+import ephem
+
+LAT, LON = 72.2232, 15.6267 # svalbard
+ON, OFF = 0, 1
+RELAY_PIN = 19
+SUN_ANGLE = -18 # astonomical twilight
+
+def main():
+
+    # GPIO Setup
+    GPIO.setmode(GPIO.BCM)
+    GPIO.setup(RELAY_PIN, GPIO.OUT)
+
+    # ephem setup
+    observer = ephem.Observer()
+    observer.lat = str(LAT)
+    observer.lon = str(LON)
+    sun = ephem.Sun()
+
+    while True:
+        observer.date = datetime.now()
+        sun.compute(observer)
+
+        if sun.alt > SUN_ANGLE:
+            GPIO.output(RELAY_PIN, ON)
+        else:
+            GPIO.output(RELAY_PIN, OFF)
+
+        time.sleep(60) # check every min
+
+if __name__ == '__main__':
+    main()