Engineer from Télécom Paris
Ph.D Thesis from UPMC

Network & Security IT - Le RSI
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Motorized Camera controlled by the telephone

For some years, I lodge different pets at home (Cat, Chinchilla, Hamsters).


Each time I tried to phone one of them, I was unable to understand what he said : I tried but never succeeded in teaching any human language to them. So, I created this motorized Camera controlled by the telephone, in order to supervise them when I'm at my office.


The system is made of 3 parts:

  • 1- a private PBX based on Asterisk: this Linux PC is connected to the PSTN. When it receives a phone call, it converts DTMF signals to commands sent into an asynchronous V.24 interface (RS-232-C),
  • 2- an electronic box based on a micro-controller that receives commands from a V.24 interface and is able to drive a motor (stepper),
  • 3- an USB camera attached to the stepper, broadcasting to the Internet.

The command part of the box is based on a microcontroller (Microchip PIC16F876) connected to my personal PBX (PC running Asterisk) through a serial port (thanks to the well-known MAX232N, a +5V-powered RS-232 driver). The power part is made of a quadruple half-H driver (L293D from Texas Instruments) driven by 4 inverters packaged in a SN7416.
Here are the schematics:

command part

power part

camera part

stepper part

SN476 + L293D both from Texas Instruments


What about the software parts ?

- The assembler code for the PIC is available here.
- In your PBX dial plan (Asterisk configuration file extensions.conf), you need to add the left and right actions (in this example, press 7 and 8 to let the camera rotate left and right):
; stepper
exten => 7,1,System(/bin/stepper-left-digium.sh)
exten => 7,n,Goto(s,begin)
exten => 8,1,System(/bin/stepper-right-digium.sh)
exten => 8,n,Goto(s,begin)

- These shell scripts call /bin/stepper (see stepper.c).

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External Links:

ImageMy Former Web Site
Since 04/26/01, I maintain a web site named www.fenyo.net. Since I made many updates recently, click here to access the original content, where old informations are kept. The photo is also from 2001 :-)

ImageAgnes' Web Site
Agnes, my wife, maintains a web server where you will find plenty of original resources : free software from her own production, probability courses, exams' corrections, photos of her trips in the US... Do not hesitate to visit her site, she will be glad to see her access.log growing !

ImageCanardou's Web Site
Canardou has always been for me a friend that really matters, helping me in every situation. According to informations currently available, Canardou could be affected by the H5N1 virus. So, for a few weeks, Public Health Bird Regulations have made me forbid Canardou to walk away from our appartement. Feel free to take news about him from his personal home page.

Private Links:

ImageMail for nuts
Authorized users at domain fenyo.net can read/send mails by means of this cute Squirrel (a friend of Canardou ?).