zondag 17 augustus 2014

Pi-files: Frontdoor light switch based on local sunset/sunrise

I have a couple of front door LED lights which I would like to switch on automatically during the evening/night. The two conventional methods that are commonly available had their disadvantages:

A timer switch is the easiest and cheapest solution, but doesn't take into account day light savings. Besides that, in Einhoven, the Netherlands where I live in december the sun sets around 16:30 while in June it doesn't get dark before 22:00. A simple timer doesn't take that into account either.

Since you only want the lights on when it gets dark, instead of time you can also use a light sensor to distinguish day and night. You have these front door lights that have this built in. The problem that I had with these devices is that they start bouncing ('flickering') around sunset/sunrise. They constantly turn on/off which causes damage to the LED lights I was using. This cost me already several expensive led lights.

Since I already have a Raspberry Pi installed in the hall way (used for the doorbell alert) I might as well hook up the front door lights. You can find on the Internet all sorts of timetables for the sunset/sunrise, so my Rpi should be able to use that same information as well. A small search on the world wide web led me to a Python package called PyEphem. This package can be used to do astronomical calculations and can tell you for example where a certain object (e.g. the sun) is with respect to the observer (which is me standing in my front yard). Very conveniently it also can calculate for you the upcoming sunset and sunrise. Isn't that exactly what I need?!?

The LED lights are powered with a 12V AC-DC transformer. I put together a small electronics board to be able to use the GPIO's 3V3 of the Rpi to switch the 12V LEDs. I used a IRL3103 N-FET. This is not really a deliberate choice but like most of my transistor/FET choices based on what I have lying around in the lab. Be aware that the N-FET needs to be able to switch with a Gate-Source voltage of 3V3. For example an IRF540 (which I used for a motion detector for a 12V ledbar) doesn't switch with this voltage (Here I solved it by using a smaller BS170 N-FET and use that to switch a IRF 9540 P-FET). I added a manual switch to override the automatic switch in case I just want to turn on the lights. Parallel to the front door LEDs is a test led with a resistor onboard to be able to test the functionality without having to connect the actual front door lights.

I use GPIO pins 18 and 22 to switch the two LED's. You can switch LED's with only one output, but I thought it is a nice additional feature to switch them separately to be able to also create a spooky program for Halloween or something like that.
After including the PyEmphem package I have to indicated where the observer is located. I used itouchmap which can translate an address to a latitude and longitude coordinates. Being an observer in Eindhoven means you are located at [51.5, 5.5]. The PyEphem package calculated the next sunrise and sunset and returns these values. I do this every minute and compare the two; if the next sunset if further away in time than the next sunrise, it means it is night. The other way around means daytime. The LED lamps are switched based on the day/night status.

The code can be found here (link):

maandag 4 augustus 2014

Pi-files: Doorbell alert with pushmessage and mail with webcam footage

Actually the first 'project' I ever did with a Raspberry Pi was sending a push message to my Iphone. It was 2012, I was lying sick in bed and found a new app on my Iphone called Pushover (what else to do when you're sick?). With Pushover you can send and receive custom made push messages. On the website I found a simple Python script to send messages. I knew the Rpi was able to run Python code, so here my Rpi adventures started. Within 30 minutes I was able to receive 'hello world' on my phone (needless to say I wasn't lying in bed anymore). Seeing 'hello world' on your screen is like the software equivalent of the blinking led, THE coolest feature ever!

I decided to hook up this push message feature with my doorbell. The idea is that every time somebody rings the doorbell, I get a push message that there is somebody at the door. The wires of the doorbell were already connected to a wireless transmitter and I wanted to keep that functionality. I used a relay to combine the transmitter with a switch on the GPIO header of the Raspberry Pi.

The led and 330R resistor can be installed in the actual doorbell, so the person can find the doorbell and is triggered when the button is pressed in case he/she doesn't actual hear the bell (the led turns off when the doorbell is pressed). The 100u capacitor and flyback diode are to limit voltage peaks when using the relay. The 'test' switch is available close to the GPIO header to test the (software) functionality of the doorbell alert. The relay and test switch are connected to pin11 (GPIO0) of the Rpi.

The Python code looks as follows. First the necessary libraries are included and the GPIO header is configured:

#import libs
import RPi.GPIO as GPIO
import httplib, urllib
import time
from time import sleep, localtime, strftime

#display no warnings (on command line)
#set GPIO: use RPi board pin numbers
GPIO.setmode(GPIO.BOARD)  #alternative is GPIO.BCM (Broadcom names)
#set pin 11 as input
GPIO.setup(11, GPIO.IN)  #Input: doorbell (relay)

A seperate function is written for the push message. This is mainly copied from the Pushover FAQ section ('How do I send Pushover notifications in Python?'). The token ('push_token') and user ID ('push_user') you get when you sign in on the website. There you can also select the devices on which you want to receive the push messages.

#set up push message (pushover)
def push(text):

   push_token = 'xxx'
   push_user   = 'yyy'

   conn = httplib.HTTPSConnection("api.pushover.net:443")
   conn.request("POST", "/1/messages.json",
                urllib.urlencode({"token": push_token,
                                        "user": push_user,
                                        "message": text,}), 
             {"Content-type": "application/x-www-form-urlencoded" })

The main loop checks for the GPIO input regularly. I added a tiny bit of delay (sleep) to relieve the CPU. When the doorbell is pressed, it takes the current date and time and adds that to the push message.

while 1:

    sleep(0.1) #relieves CPU load big time!
    #if doorbell is pressed...
    if GPIO.input(11):

          #determine date/time and add to message
          timestr_date = strftime("%a %d %b %Y", localtime())  
          timestr_time = strftime("%H:%M:%S", localtime())      

          mess = "Doorbell pressed on {}, {}.".format(timestr_date,timestr_time)
          print "\n"
          print mess


When this all worked it was time to extend the doorbell alert feature. Not only I want to know that there is someone at the door, I also would like to know who was at the door, especially when I am not at home. I added a Logitech C270 webcam to the setup to capture snapshots and a short movie.

A Python mail script is supposed to send it all to my mailbox. The mail functionality I didn't invent myself, I just relied on the beautiful internet community. On Kutuma's Ramblings I found almost exactly what I needed. The only difference is that I wanted to sent multiple attachments. For that I changed the mail function a little bit:

def mail(to, subject, text, attachments=[]):

   gmail_user = 'XXX@gmail.com'
   gmail_pwd  = 'YYY'

   #add attachments to a list
   assert type(attachments)==list

   msg = MIMEMultipart()

   msg['From']    = gmail_user
   msg['To']      = to
   msg['Subject'] = subject


   for attach in attachments:
     part = MIMEBase('application', 'octet-stream')
     part.set_payload(open(attach, 'rb').read())
           'attachment; filename="%s"' % os.path.basename(attach))

   mailServer = smtplib.SMTP("smtp.gmail.com", 587)
   mailServer.login(gmail_user, gmail_pwd)
   mailServer.sendmail(gmail_user, to, msg.as_string())

You can now add the attachments as an comma separated array:


As you can see I added three snapshots and one movie as attachments. They all come from the Motion package which is a linux package to capture motion on a webcam. To be honest, I actually don't use the motion feature of that package, but I tried several other solutions (like FFMpeg or something) and came across a bunch of issues with compiling, frame rates etc. The Motion package served my purpose the best. 

NB. The Raspberry Pi that I am using is a model A, which is not capable of using the official Rpi camera module with its cool movie and snapshot features.

To install the Motion package, run the following command:
pi@raspberrypi ~ $  sudo apt-get install motion libv4l-0 uvccapture

I added some additional modules to the import section of the Python script described above and added the code below to the main loop. Starting the webcam is done right after the doorbell is pressed. After capturing the snapshots and sending the push message, the program waits 60 seconds until the webcam is stopped. After this the mail is send with the snapshots and movie.

import subprocess
import shutil #high-level file operations

    #if doorbell is pressed...
    if GPIO.input(11):

          #start webcam (motion package)
          print "\n"
          print "Start webcam (Motion)"
          #subprocess.call("sudo /etc/init.d/motion start", shell=True)
          subprocess.call("sudo motion", shell=True)

          #copy (save) most recent snapshot of webcam
          print "\n"
          for k in range(3):
               sour_path = '/home/pi/rpi/webcam/motion/snapshot.jpg'
               dest_file    = '/home/pi/rpi/webcam/motion/screen%d.jpg' %k
               shutil.copy2(sour_path, dest_file)
               print 'Snapshot captured:  %s' %(dest_file)

          ****** Sending push message (see above) ******

          print "wait 60 seconds"
          #stop webcam
          print "Stop webcam"
          subprocess.call("sudo /etc/init.d/motion stop", shell=True) 

          #send mail via Gmail


The motion package has a pretty big configuration file where you can configure all sorts of things. Most of the items speak for their own. The file can be edited with nano:

pi@raspberrypi ~ $  sudo nano /etc/motion/motion.conf

For the doorbell alert let me highlight the most important sections:

# File to store the process ID, also called pid file. (default: not defined)
process_id_file /var/run/motion/motion.pid 

The folder /var/run/motion needs to be present. In my latest Raspbian (Debian Wheezy) OS I encountered a bug (as far as I can tell) that this folder is gone every time I boot up the Rpi. For that reason I added a check and create the folder if necessary:

import os

folder   = "/var/run/motion"

if not os.path.exists(folder):
  print "Folder does not exist. Create folder " + folder

# Image width/height (pixels). Valid range: Camera dependent, default: 352/288
width 1280
height 720
Bigger images won't hurt!

# Maximum number of frames to be captured per second.
# Valid range: 2-100. Default: 100 (almost no limit).
framerate 2

I only use two frames per second to keep the movie size as small as possible.

# Always save images even if there was no motion (default: off)
output_all on

I don't use the motion detection features so I want all images to be saved

# Use ffmpeg to encode a timelapse movie
# Default value 0 = off - else save frame every Nth second
ffmpeg_timelapse 0.5

# Make automated snapshot every N seconds (default: 0 = disabled)
snapshot_interval 1

Save snapshots every second

# Target base directory for pictures and films
# Recommended to use absolute path. (Default: current working directory)
target_dir /home/pi/rpi/webcam/motion

Location where all files are stored

# File path for snapshots (jpeg or ppm) relative to target_dir
snapshot_filename snapshot

All snapshots are given the same name (no timestamp) to save storage space.

# File path for motion triggered ffmpeg films (mpeg) relative to target_dir
movie_filename movie

Each movie is given the same name (no timestamp) to save storage space.

That's it for now! I am already thinking of new features like face recognition, direct videostream, and a call back option to actually talk to the person at the door wherever I am. The sky is the limit! Unfortunately my spare time as well :)

Below a picture of my custom storage box which is located in the meter cupboard (again, is that really the correct translation for the dutch word 'meterkast'?). It houses a Raspberry Pi model A, an interface board (on the right) with the well famous heartbeat led. On the left two boards for the doorbell and one for the front door light which I will explain in another post soon.