TV Watching Safety Distance
Enforcer
Dr. Abdelhafid Bouhraoua
Mr. Kamel Chenaoua
Outline
• Aim of the Project
• Principle of Operation
• The Components
• Implementation
• Issues
• Competition
• Perspective
Aim of the Project
To provide a way that prevent
children from watching TV from a
close distance to safeguard their
eyes health
Principle of Operation
From
ANT
To TV
Distance
Monitoring
Device
How Does it Work
From
ANT
To TV
• Distance Measuring Device
Continuously Monitors Distance
to closest Object (Body) in
Range
• If Object Detected: Turn Off
Antenna Input
Distance
Monitoring
Device
Components
• Distance measuring sensors
• Electrically controlled On/Off switch
• Microcontroller with communication
means to interface the sensors
Distance Sensors
- infrared From Sharp Electronics:
Many ranges and two interface types:
• Digital
– Parallel or Serial Interface
• Analog
Distance Sensors
- infrared • Maximum range is 130 cm for the
sensor with the analog interface
• Inaccurate measurements above 80 cm.
• Fragile devices not meant for industrial
quality.
• Digital sensors did not respond to
datasheet specifications and could not
be used
• Analog sensors were properly
interfaced
Distance Sensors
- Ultrasound From Devantech:
Acquired one device from a family of
three:
• SRF-08 Range Finder:
– Standard two wire I2C
Interface
– Senses Objects up to 6 meters
– 15 mA current max
Distance Sensors
- Summary • Ultrasound SRF-08 sensor was used in the
prototype
– Advantages
• Robust, reliable product
• Large range
– Disatvantages
• Price (around $40)
• Marketing ultrasound in pet environments
• Infrared Sensors
– Advantages:
• Price ($5 to $15)
– Disatvantages
• Fixed distance measuring (On/Off)
• Unreliable
On/Off Switch
Either a:
• Relay
• Transistor (MOSFET)
Used a Relay for simplicity of interfacing
Microcontroller
Rabbit Semiconductor Ltd.:
Offers a wide range of
Microcontroller cores:
Acquired the RCM 3700
Microcontroller
RCM 3700 features
• 512K SRAM
• 512K Flash
• Ethernet for Networked Applications
including web-enabled embedded apps.
• Many standard interfaces:
– USART, SPI, I2C, SCI, Parallel Ports
• Many Timers for clock generation and
PWM
• Provided Development Environment
• Standard ANSI-C language programming
environment
• Many libraries spanning as wide as:
– PWM, SPI, USART, GPS, Timer Control,
TCP/IP, etc …
Implementation
A PCB board was designed and fabricated .
PCB Schematic below:
D1
7805
C1
C2
C3
Ra
bbi
t
Int
erf
ace
R1
+5V
GND
SCL
SDA
RC
LC
Ant
enn
a
Inp
ut
LED1
R2
+5V
GND
SCL
SDA
Relay 1
T
1
Ant
enn
a
Out
put
SR
F0
8
Int
erf
ace
Problems and Issues
• Space problem
• Test and Lab Equipment Shortage
• Dong Jr. was a Great help. No Technician
support after he left
• Component acquisition problem
• Reimbursement turnaround time
• Student lack of interest
• Lack of publicity for the program
– Suggestion: Creation of web page for the
innovation projects
Competition
Taiwanese Company has designed a
similar product and is shipping it (link
below). Chinese Patent Pending
http://tech.monstersandcritics.com/news/
article_1075388.php/Taiwan_firm_invents
_gadget_to_stop_kids_from_sitting_too_cl
ose_to_TV
Proves that we are on the RIGHT TRACK
Perspective
• Cost reduce the product further
– Replace Rabbit core by PIC microcontroller
or similar cost microcontroller
• Add keypad and display for
programming sensor cut-off distance
• Using a High-Frequency MOSFET as
switch.
• Competition proposed price is $450
• Our Cost can be reduced to around $70