detect_person.py

#!/usr/bin/python
import time
import subprocess
import signal
import logging

from range_sensor import RangeSensor

from graceful_kill import GracefulKiller

logging.basicConfig(format='%(asctime)s: %(message)s',datefmt='%m/%d/%Y %I:%M:%S %p', filename='/var/log/detect_person.log', filemode='w', level=logging.INFO)

r = RangeSensor()

gk = GracefulKiller()


def turn_tv_on():
  subprocess.call(['/home/pi/tv_on.sh'])

def turn_tv_off():
  subprocess.call(['/home/pi/tv_off.sh'])


STATE_OFF=0
STATE_ON=1

thresh = 50	#cm
t_start =0 
t_on=314 #time to stay on, in seconds
if __name__=="__main__":
  logging.info("Starting up...")
  distance=r.read()
  old_distance=distance
  state = STATE_OFF
  while True:
    if gk.killed():
      logging.info("Now shutting down, received signal")
      break
    old_distance = distance
    distance= r.read()
    if state==STATE_OFF:
      if ((old_distance - distance) > thresh):	#only when someone moves closer
        state=STATE_ON
        turn_tv_on()
        t_start = int(time.time())
        logging.info("MIRROR ON")
        logging.info("DISTANCE: %f  OLD DISTANCE: %f"%(distance,old_distance))
    elif state==STATE_ON:
      if ((t_start + t_on) < time.time()):
        logging.info("MIRROR OFF")
        state=STATE_OFF
        turn_tv_off()
  turn_tv_off() 
        
    
    

detect_person.service

[Unit]
Description=Service to turn on tv when someone is in front of it

[Service]
Type=simple
ExecStart=/home/pi/detect_person.py
RemainAfterExit=yes

[Install]
WantedBy=multi-user.target

graceful_kill.py

import signal
import time

class GracefulKiller:
  kill_now=False
  def __init__(self):
    signal.signal(signal.SIGINT, self.exit_gracefully)
    signal.signal(signal.SIGTERM, self.exit_gracefully)

  def exit_gracefully(self,signum,frame):
    self.kill_now=True

  def killed(self):
    return self.kill_now

range_sensor.py

#!/usr/bin/python
import RPi.GPIO as GPIO
import time

TRIG = 23 
ECHO = 18

class RangeSensor:

  def read(self):
    GPIO.setmode(GPIO.BCM)
    GPIO.setup(TRIG,GPIO.OUT)
    GPIO.setup(ECHO,GPIO.IN)
    
    GPIO.output(TRIG, False)
    time.sleep(2)
    
    GPIO.output(TRIG, True)
    time.sleep(0.00001)
    GPIO.output(TRIG, False)
    
    while GPIO.input(ECHO)==0:
      pulse_start = time.time()
    
    while GPIO.input(ECHO)==1:
      pulse_end = time.time()
    
    pulse_duration = pulse_end - pulse_start
    
    distance = pulse_duration * 17150
    
    distance = round(distance, 2)
    GPIO.cleanup()
    return distance
    

tv.service

[Unit]
Description=Control power to tv

[Service]
Type=oneshot
ExecStart=/home/pi/tv_on.sh
ExecStop=/home/pi/tv_off.sh
RemainAfterExit=yes

[Install]
WantedBy=single-user.target

tv_off.sh

#!/bin/bash


#if tv is on, turn it off

POWER_ON=$(/home/pi/tv_read_power_state.sh)

if [ "$POWER_ON" = "1" ]; then
  /home/pi/tv_toggle_power.sh
fi

tv_on.sh

#!/bin/bash


#if tv is off, turn it on

POWER_ON=$(/home/pi/tv_read_power_state.sh)

if [ "$POWER_ON" = "0" ]; then
  /home/pi/tv_toggle_power.sh
fi

tv_read_power_state.sh

#!/bin/bash


gpio -g mode 15 in
gpio -g read 15

tv_toggle_power.sh

#!/bin/bash


gpio -g mode 14 out
gpio -g write 14 1
sleep 0.25
gpio -g write 14 0