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Android-Powered, Automated Cat Feeder

This is my Android-powered, automated cat feeder:

The attached HTC Magic is running SL4A and provides scheduled and on demand feeding as well as an MJPEG webcam feed. Feeding is triggered via Bluetooth. The Arduino is hooked up to a SparkFun BlueSMiRF and a simple relay circuit I made on perfboard for powering the motor on and off.

The brackets and food chute were designed in SketchUp and printed on my MakerBot. You can find all the SKPs, STLs, schematic, and parts list on Thingiverse.

Here's the 50 odd lines of Python code running on the phone via SL4A that make the magic happen:
import android # See
import gsd  # See
import socket
import threading
import time

def feed(droid):
  droid.bluetoothConnect('00001101-0000-1000-8000-00805F9B34FB', '00:06:66:04:b2:07')

class Server(gsd.App):
  def __init__(self, droid, webcam_url):
    self._droid = droid
    self._webcam_url = webcam_url

  def GET_(self, response):
  <title>Cat Feeder</title>
  <img src="%s">
  <br><a href="/feed">Feed!</a>
  </html>""" % self._webcam_url)

  def GET_feed(self, response):

def timer(droid):
  feedings = [4, 10, 20]
  last_feeding = None
  while True:
    hour = time.localtime().tm_hour
    if hour in feedings and hour != last_feeding:
      last_feeding = hour

def GetIpAddress():
  s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) 
  s.connect(('', 0))
  return s.getsockname()[0]

def main():
  droid = android.Android()
  webcam_url = 'http://%s:%d/' % tuple(droid.webcamStart(5, 80).result)
  server = Server(droid, webcam_url)
  port = 8080
  base_url = 'http://%s:%d/' % (GetIpAddress(), port)
  threading.Thread(target=server.Serve, args=('', port)).start()
  threading.Thread(target=timer, args=(droid,)).start()
  droid.notify('Cat Feeder', 'Running on: %s' % base_url)
if __name__ == '__main__':
And here's the Arduino code:
int relayPin = 13;
int portionSize = 10000;

void setup() {
  pinMode(relayPin, OUTPUT);

void loop() {
  if (Serial.available() > 0) {;
    digitalWrite(relayPin, HIGH);
    digitalWrite(relayPin, LOW);
This project was inspired by the Internet-Enabled Cat Feeder - Mark 2.


  1. Cool! How do you run Python on Android? I was not aware that this is possible. A simple port of Jython? Can you provide some links?

  2. Thanks! The phone is running SL4A which enables running Python scripts. I updated the post to be more explicit about that.

  3. I bought one of these feeders for the exact same purpose! Unfortunately, I only have it mounted to the wall and don't have it automated yet. Could you provide some details on the motor and how you connected it to the feed mechanism? Thanks.

    BTW - as part of my other projects, I'm developing a 6LoWPAN module that I was planning on using for my motor controller. Basically I would have an IPv6 controlled cat feeder.

  4. The motor mount and bracket were printed on my MakerBot. Check out the Thingiverse page for the SketchUp files and circuit schematic. Your motor controller sounds cool :)

  5. Specifically, could you share what motor you got and were you got it from? I'm curious as to what type of gear motor is strong enough to operate the mechanism. I know in my trials of gear motors for a mini blind controller, I realized that a fair amount of torque is required to operate the blinds.

  6. The parts list is also available on the Thingiverse page.

  7. Oops, I missed the parts list over there. Sorry for bugging you about that.

  8. This is so cool! Is Next Step that real-time comm PC<->android by WebSocket of HTML5?

  9. Hi,

    This is cool. I have a question. In ASE, bluetooth is for API level 5. HTC Magic (Android 1.5) is only API level 3. How did you overcome that?



  10. Oh..that's why. It's beyond my capability. u did great job (i mean your contribution on ASE)!

  11. Hi Damon-

    Can you provide some details on what cereal dispenser you used? Did you build your own or did you use the same Zevro dispenser?


  12. Check out the Thingiverse page for the parts list, SketchUp files, and circuit schematic.

  13. Great job, Damon! How are you doing the droid.webcamStart(...) thing? It doesn't seem to be a part of the SL4A API. I see you referring to but that is too cryptic to me (can you show a context how are you using it?). Trying not to get my hands too dirty (looks like may be inevitable though) so love the idea of Python on the phone...

    Appreciate your help!

  14. It's done using an unreleased SL4A API. You can try it today with the unofficial release.

  15. Hi Damon,
    I'd like to specify my bluetooth SL4A baudrate, how can I do?

  16. Hi Liostra,

    There is no baudrate for Bluetooth connections. Maybe you could elaborate a bit more on your problem? Also, try the SL4A user group:

  17. Hi, I saw the GSD module in your code and decided to look it up. I found no documentation whatsoever. I'm guessing you made it for your own personal use but can you point me to somewhere I can find some basic introduction/examples of using it.

  18. <<<<>>>>>>

    Ok, I found an example program (ShoutOuts) which looks really cool. I like the way that directories go to functions. But I'm getting a no data received page in chrome and errors in the console, namely:

    Traceback (most recent call last):
    File "C:\pythonstuff\", line 70, in do_GET
    get(self, **cgi.parse_qs(qs))
    TypeError: GET_() got multiple values for keyword argument 'shout

  19. @mgthefourth

    I've pushed some fixes. I suggest pulling the latest shouts example and gsd module from the project site.

  20. Beautiful, works like a charm.

    Consider me officially subscribed to your blog.

    Don't stop making amazing stuff!

  21. Hi Damon,

    Great work!!! Just have one quick query, would this be possible by creating a serial connection from the micro-usb port on the Android device to the Arduino? I'm just curious to see if the use of bluetooth could be circumvented.


  22. @Martin

    Take a look at the ADK and the IOIO.


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