Presentation to 5th sem students of Amity School of Electronics. Vinay and Rashmi made this presnetation.

1. Electronics - Embedded - Entreprenurship

2. Agenda
About me
About Embedded & Electronics
About You
Why I am here
Inviting you to work with us

3. Me - Professional
Vinay Chaddha. Electronics Hobbyist.
Author. Innovator. Passionate about
learning and sharing.
Filed 3 patents, Shared five successful
commercial projects. Many copy rights.
Developed over 200 comemrcially
successful projects.

4. CONSTRUCTION CONSTRUCTION Remote-controlled centre values of treble, balance and
bass. Volume will be set at 50 per cent
of the maximum value and the relay
Audio Processor Using
will be off. Loudness and mute will also
remain in the off mode. A remote hand-
set can be used to change the settings
as desired.
Caller-ID Unit Using
transmit the telephone number of call-
Microcontroller
Audio controller. TDA7315 is a
ing party just before the first ring while single-chip I2C bus-compatible audio
in systems used in USA and China, the controller which is used to control all
data relating to the calling number is functions of the audio amplifier. Stereo
Micro-controller
sent between first and the second rings. audio input from the preamplifier is fed
The number of calling party in India is OO to the IC input. A microcontroller can
SAG
transmitted by MTNL/DoT exchanges VINAY CHADDHA G.S.
in DTMF codes. PARTS LIST
ILLO
N Two documents containing stan- Semiconductors:
M
. DH
A.P.S dards and specifications issued by DoT’s IC1 - TDA7315 digitally controlled
VINAY CHADDHA ost hi-fi audio CD systems and 3. audio processor
Telecommunications Engineering Cen-
nowadays are available with IC2 - MC68HC705KJ1CP Motorola
tre (TEC) in the form of ‘Generic re-
T
remote control. However, no microcontroller (GVC-AMP-
he facility of knowing your tended to the normal telephone users quirements’ and ‘Interface require-
such circuit is available for adding to
Description 257)
caller’s telephone number before also in Delhi, Mumbai and some other ments’ for ‘Subscriber service unit for Memory. 24C02 is an I2C bus compat-
IC3 - 24C02 I2C serial EEPROM
the AF power amplifiers made as hobby IC4 - 7805 fixed regulator +5V
answering the call, which has cities of India through MTNL and DoT calling line identification presentation ible 2k-bit EEPROM, organised as 256
projects. The design of such an add-on IC5 - 7809 fixed regulator +9V
been available to cellular phone users since 1st January. (SSU for CLIP)’ are available from TEC, x 8 bits. It can retain data for a period
circuit along with remote control is pre- IC6 - µPD6121 infrared remote
only in India so far, has now been ex- MTNL/DoT telephone exchanges Khursheed Lal Bhawan, Janpath, of more than ten years, including the control
sented here. It can be used by hobby-
T1,T2,T3 - BC547 npn transistor
ists as an attachment to their audio current settings of volume, treble, bal- T4 - 2SC2001 npn transistor
power amplifiers. ance, bass, as well as the on/off status D0-D7 - Red LED
This design is based on audio con- of the main amplifier unit or the relay D8, D10-D11 - 1N4007 rectifier diode
troller TDA7315 from SGS-THOMSON status. The various audio parameters D9 - 8.2V,0.5W zener
can be stored in just six bytes. D12 - IR LED
and Motorola microcontroller
MC68HC705KJ1. The microcontroller, Mains power failure is quite com- Resistors (all 1/4W, ± 5% metal/carbon film,
unless stated otherwise)
after programming with the specific mon in India. This does not allow the
R1,R2,R15,R16- 10-kilo-ohm
software code for the current applica- last settings of volume, tone and bal- R3,R4,R14 - 1-kilo-ohm
tion, has been renamed GVC-AUD- ance to remain intact. To overcome this R0,R5-R9,
257. Other construction projects by the microcontroller unit (MCU) must R12,R13 - 330-ohm
the author using the same series of store all audio settings of the user in R10,R11 - 5.6-kilo-ohm
memory (EEPROM). The memory en- R17 - 2-ohm, 0.5W
microcontrollers, which can be referred R18,R19 - 200-kilo-ohm
to for additional details, have been pub- sures that even after a power trip, the
Capacitors:
lished in EFY in Jun. ’97 (Set-Top Con- MCU will read the latest saved settings
C1 - 10µF, 16V electrolytic
verter) and Apr. ’99 (Caller ID). In ad- from the EEPROM. C2-C4,C7,
dition to audio controller and Using two lines, SCL (serial clock) C19,C20 - 0.1µF ceramic disc
microcontroller the circuit comprises and SDA (serial data), the microcon- C15,C16,C9,
the following standard parts that are troller can read and write six bytes for C10,C11,C13 - 0.1µF polyester
C5,C6 - 33pF ceramic disc
used in any normal system: all the audio parameters. For more de- C8 - 22µF, 25V electrolytic
1. Power supply tails on I2C bus and memory interfac- C12,C14 - 2.7nF polyster
2. LED indicator panel to indicate ing, please refer to Caller ID construc- C17,C18 - 2.2µF, 16V electrolytic
status/keys pressed tion project in Apr. ’99 issue of EFY. C21,C22 - 220pF ceramic disc
At power ‘on,’ the last-saved audio C23 - 10µF, 50V electrolytic
3. Relay to switch on/off the supply
to the power amplifier or the main unit settings are read by the MCU. In case Miscellaneous:
memory IC cannot be read by the RL1 - 12V, 150 ohm, SPST relay
The following parts are used in re- OEN Pt. No. 57DP-12-1C6
mote systems for VCR, TV, etc: microcontroller, volume LED will blink XTAL - 4MHz quartz crystal
1. Memory (24C02). three times to indicate the problem. The Y - 455kHz, ceramic resonator
2. Remote handset with 12 keys possible reasons could be either a bad - Battery 1.5V, pencil cell
3. IR receiver for remote operation memory IC, or a discontinuity/shorting - IR sensor module
- Remote control handset,
Functionality of these parts is ex- of its tracks, or improper insertion of complete with keyboard
plained below with reference to Figs 1 the IC in its socket. - Connectors for audio input-
The author is the proprietor of GVC Systems, Under the circumstances, the unit output and power supply
will still work, but it will not remem- - 12V DC, 250mA battery
Noida. He can be approached through e-mail
eliminator
at gvc@vsnl.com ber the last settings and will select the
52 ELECTRONICS FOR YOU SEPTEMBER '99
Fig. 1: Complete circuit diagram of caller-ID unit
CC O NTS T RTU O N I O N
ONS RUC I CT
44 ELECTRONICS FOR YOU APRIL '99
MICROCONTROLLER-BASED
CMYK
CONSTRUCTION MAR
IL KU
ACCESS CONTROL SYSTEM
SUN
BEVERAGE VENDING
VINAY CHADDHA* the password data for over ten years. PARTS LIST
MACHINE CONTROLLER The user can modify the password as
S
EO
SANI TH Semiconductors:
ecurity is a prime concern in our day- well as relay-activation time duration for IC1(U1) - MC68HC705KJ1
to-day life. Everyone wants to be as door entry. This version of software microcontroller
much secure as possible. An access- enables use of the unit even without the IC2 (U2) - ST24C02 I2C EEPROM
control system forms a vital link in a secu- I2C EEPROM. (However, without EEPROM, IC3 (MN1) - MN1280 reset stabiliser
VINAY CHADDHA rants and even in companies. Press a allow compact size, higher reliability, rity chain. The microprocessor-based digi- the password and relay-activation time IC4 (Reg1) - 7805 +5V regulator
switch and the machine delivers a hot lower cost and multiple functionalities. T1, T2 - BC547 npn transistor
B
tal lock presented here is an access- duration will be reset to default values
everage vending machines are cup of your favourite drink. This tea/coffee/soup vending ma- (Q1, Q2)
control system that allows only authorised on interruption of the power supply.) D1, D2 - 1N4007 rectifier diode
commonplace at railway sta- This looks quite a simple operation chine controller uses Freescale’s latest persons to access a restricted area. LED1 - Red LED
tions, airports, fast-food restau- but has a very complex logic behind MC908JL16 microcontroller chip. The
it: It involves use of controller is programmable and user-
Hardware details Resistors (all ¼-watt, ± 5% carbon, unless
twelve precision timers friendly. You can set the quantity of
System overview Fig. 2 shows the access control circuit. Its
stated otherwise):
R1-R6 - 10-kilo-ohm
and four counters apart the beverages through a button switch The block diagram of the access-control main components are a microcontroller, R7-R9 - 1-kilo-ohm
from physical devices like provided on the front panel of the con- system is shown in Fig. 1. The system I2C memory, power supply, keypad, relay,
Capacitors:
display, solenoid and mo- troller as per your requirements. Thus, comprises a small electronic unit with a and buzzer.
C1, C2 - 33pF ceramic disk
tor to deliver water and cups of any size can be filled at any numeric keypad, which is fixed outside the M ic r ocon t r olle r . The 16-pin
C3, C4,
premixed tea/coffee/soup time. entry door to control a solenoid-operated MC68HC705KJ1 microcontroller from C6, C7 - 0.1µF ceramic disk
powder in exact quantity lock. When an authorised person enters a Motorola has the following features: C5 - 10µF, 10V electrolytic
for better taste and in ex- The hardware predetermined number (password) via the • Eleven bidirectional input/output Miscellaneous:
act sequence. Fig. 1 shows the block diagram of the keypad, the relay operates for a limited time (I/O) pins
Xtal (Y1) - 4MHz quartz crystal
to unlatch the solenoid-operated lock so the • 1240 bytes of OTPROM program PZ1 (BZ1) - Ceramic piezo buzzer
This has become pos- vending machine controller. It com-
door can be pushed/pulled open. At the end memory Con1 - Power-supply connector
sible because of the use of prises the following sections: power
The prototype of beverage vending machine controller of preset delay, the relay de-energises and • 64 bytes of user RAM Con2 - 2-pin male/female Berg
developed by the author microcontrollers, which supply, microcontroller, relays, relay connectors
the door gets locked again. If the entered • 15-stage multiple-function timer
driver, alphanumeric Out of eleven I/O pins, seven lines - 7-pin male/female Berg
password is correct the unit gives three
display, keyboard and small beeps, and if the entered password is have been used for the keyboard, one for connectors
memory. The power SW1-SW12 - Tactile keyboard switch
wrong it gives a longer beep of one second. the buzzer, one for relay operation, and RL1 (RLY1) - 1C/O, 12V, 250-ohm
supply circuit is shown The system uses a compact circuitry two (SCL and SDA, i.e. serial clock and miniature relay
in Fig. 2. built around Motorola’s MC68HC705KJ1 serial data lines) for communication with
The control unit microcontroller and a non-volatile I2C I2C EEPROM.
uses low-cost, readily EEPROM (ST24C02) capable of retaining I2C memory. A two-wire serial EEPROM ible 2048-bit (2-kbit) EEPROM is organised
available components. (ST24C02) is as 256x8 bits. It can retain data for more
The temperature con- used in the than ten years. Using just two lines (SCL
trol section has not circuit to re- and SDA) of the memory, the
been included in the tain the pass- microcontroller can read and write the
design as the parts re- word and the bytes corresponding to the data required
quired are expensive relay-activa- to be stored.
and not easily avail- tion time du- (Note. For details of the microcontroller
able. However, a low- ration data. and programming of I2C EEPROM, you may
Data stored refer to the article ‘Caller ID Unit Using
cost thermostat used in
remains in the Microcontroller’ published in April ’99 is-
water heaters can be
memory even sue of EFY and the article ‘Remote-con-
Fig. 1: Block diagram of the beverage vending machine controller used in the unit.
after power trolled Audio Processor Using
Power supply. The Microcontroller’ published in Sep. ’99 is-
failure, as the
relays need 12V DC memory en- sue of EFY. For additional data on Motorola
and the microcontroller sures reading microcontrollers, refer to EFY-CDs of this
and memory need 5V of the latest year’s January and February issues. The
DC for operation. saved settings information pertaining to I2C EEPROM is
Bridge rectifier, capaci- by the available on STMicroelectronics’ Website.)
tive filter and regulator microcontroller. Power supply. The power supply unit
ICs 7812 and 7805 are This I 2 C provides a constant 5V supply to the en-
the standard parts used Fig. 1: Block diagram of the access-control system bus-compat- tire unit. This is a conventional circuit us-
in the power supply.
Microcontroller. 50 ELECTRONICS FOR YOU OCTOBER 2002
Fig. 2: Power supply circuit We need individually
WWW.EFYMAG.COM ELECTRONICS FOR YOU • OCTOBER 2006 • 77
CMYK

5. Me - Personal
Married. Stay in Noida
with Wife Geeta,
Daughter Upasana and
Pet Maggie.
Electronics is my hobby. I
have been using
electronics since the age
of 12 years. Bought
personal computer 31
years back before TV.

6. About Embedded
Today for each PC there are 49 small
tiny size micro controllers.
Every thing from Lamps, Fans, Chimneys
to Bikses, Cars, Traffic Lights, Elevators,
Battle Tanks, Missiles use them.
There is a huge demand for local/
regional products. This can not be
supplied by large companies/imports.

7. More about embedded
This needs three things
- Electronics
- Soft ware
- Creativity - Imaginations

8. How will it help you
This is part of your project. You need to
it.
Knowledge will be useful in which ever
field you work. You will be using
embedded devices.
Skills are required if you wish to join
core technical company.

9. Problems
New models of PC, Mobiles, Cars ... are
available every year.
Unfortunately, college syllabus stills
includes obsolete devices that I read 31
years back.
In a job with embedded company, your
boss may ask you to unlearn what ever
you know and then start learning
again.

10. Why I am here
To share about a project
and ask you to work with me

11. Joy-n-Freedom
We use electonics for luxury and
convenience.
Persons who are differently abled or
sick or old have limitations.
They and their familis are under stress.
We wish to work on creating
electronics projects for them and add
Joy-n-Freedom in their life

13. What we have done
Participated in t wo events
First one at National Blind School, Delhi.
Second at Viklang Kendra, Allahabad
Interacted with persons with disability,
their family members and NGOs.
There is a need and no supplies.
Imported devices are too expensive

15. Invitation
Work me with me on projects.
Work alone, as a team, in technical field,
non-technical field, just support,
feedback, share the concept, develop
website or what ever you can.........

16. Embedded Platform
Embedded devices are available from
multiple sources like Philips, Motorola,
Renesas,ST Micro, Micro chip and so ....
We can use of any of them, however
each device needs specific tools and
compilers and and some time on learning
specific details.
More than technicals it is the support
from supplier of embedded devices that

17. Our Choice
I have work on NXP (Philips), Freescale
(Motorola), Renesas(Hitachi), Microchip,
ST, Zilog, Atmel.
My choice is Freescale(Motorola) and
Atmel.
Both of them offer good developent
support. You get quick results.

18. Freescale
Freescale has some India Specific Micro
controllers.
Compilers is Code warrior 6.3
Devices are 9S08IA, 9S08IB and 9S08IC

19. ATMEL
Compiler is ARDUINO
Devices are ATMEGA168
Demo boards are available locally.

20. Projects to be made
Interfacing landline with TV
Talking clock
Universal remote for lights, fan, t v, air
con, telephone, mobile
Audio Visual Alerts for medicines
Collection of Vital Stats and updating
records. Alerts in case of serious issue

21. Contact me
name and email address by SMS to
9811074026
Send email to
vinay@joy-n-freedom.com
Visit my lab at
Amity Incubator, Amity University, Noida
Join us at
facebook.com/open.embedded

22. Thanks for your valuable time.....

23. CONSTRUCTION CONSTRUCTION
Caller-ID Unit Using
transmit the telephone number of call-
ing party just before the first ring while
in systems used in USA and China, the
data relating to the calling number is
Micro-controller
sent between first and the second rings.
The number of calling party in India is
transmitted by MTNL/DoT exchanges
in DTMF codes.
LON Two documents containing stan-
DHIL
A.P.S. dards and specifications issued by DoT’s
VINAY CHADDHA Telecommunications Engineering Cen-
tre (TEC) in the form of ‘Generic re-
T
he facility of knowing your tended to the normal telephone users quirements’ and ‘Interface require-
caller’s telephone number before also in Delhi, Mumbai and some other ments’ for ‘Subscriber service unit for
answering the call, which has cities of India through MTNL and DoT calling line identification presentation
been available to cellular phone users since 1st January. (SSU for CLIP)’ are available from TEC,
only in India so far, has now been ex- MTNL/DoT telephone exchanges Khursheed Lal Bhawan, Janpath,
Fig. 1: Complete circuit diagram of caller-ID unit
44 ELECTRONICS FOR YOU APRIL '99
CMYK

24. CONSTRUCTION
Remote-controlled centre values of treble, balance and
bass. Volume will be set at 50 per cent
of the maximum value and the relay
Audio Processor Using
will be off. Loudness and mute will also
remain in the off mode. A remote hand-
set can be used to change the settings
as desired.
Microcontroller
Audio controller. TDA7315 is a
single-chip I2C bus-compatible audio
controller which is used to control all
functions of the audio amplifier. Stereo
audio input from the preamplifier is fed
OO to the IC input. A microcontroller can
SAG
VINAY CHADDHA G.S.
PARTS LIST
Semiconductors:
M
IC1 - TDA7315 digitally controlled
ost hi-fi audio CD systems and 3. audio processor
nowadays are available with IC2 - MC68HC705KJ1CP Motorola
remote control. However, no microcontroller (GVC-AMP-
such circuit is available for adding to
Description 257)
IC3 - 24C02 I2C serial EEPROM
the AF power amplifiers made as hobby Memory. 24C02 is an I2C bus compat- IC4 - 7805 fixed regulator +5V
projects. The design of such an add-on ible 2k-bit EEPROM, organised as 256 IC5 - 7809 fixed regulator +9V
circuit along with remote control is pre- x 8 bits. It can retain data for a period IC6 - µPD6121 infrared remote
sented here. It can be used by hobby- of more than ten years, including the control
T1,T2,T3 - BC547 npn transistor
ists as an attachment to their audio current settings of volume, treble, bal- T4 - 2SC2001 npn transistor
power amplifiers. ance, bass, as well as the on/off status D0-D7 - Red LED
This design is based on audio con- of the main amplifier unit or the relay D8, D10-D11 - 1N4007 rectifier diode
troller TDA7315 from SGS-THOMSON status. The various audio parameters D9 - 8.2V,0.5W zener
can be stored in just six bytes. D12 - IR LED
and Motorola microcontroller
MC68HC705KJ1. The microcontroller, Mains power failure is quite com- Resistors (all 1/4W, ± 5% metal/carbon film,
unless stated otherwise)
after programming with the specific mon in India. This does not allow the
R1,R2,R15,R16- 10-kilo-ohm
software code for the current applica- last settings of volume, tone and bal- R3,R4,R14 - 1-kilo-ohm
tion, has been renamed GVC-AUD- ance to remain intact. To overcome this R0,R5-R9,
257. Other construction projects by the microcontroller unit (MCU) must R12,R13 - 330-ohm
the author using the same series of store all audio settings of the user in R10,R11 - 5.6-kilo-ohm
memory (EEPROM). The memory en- R17 - 2-ohm, 0.5W
microcontrollers, which can be referred R18,R19 - 200-kilo-ohm
to for additional details, have been pub- sures that even after a power trip, the
Capacitors:
lished in EFY in Jun. ’97 (Set-Top Con- MCU will read the latest saved settings
C1 - 10µF, 16V electrolytic
verter) and Apr. ’99 (Caller ID). In ad- from the EEPROM. C2-C4,C7,
dition to audio controller and Using two lines, SCL (serial clock) C19,C20 - 0.1µF ceramic disc
microcontroller the circuit comprises and SDA (serial data), the microcon- C15,C16,C9,
the following standard parts that are troller can read and write six bytes for C10,C11,C13 - 0.1µF polyester
C5,C6 - 33pF ceramic disc
used in any normal system: all the audio parameters. For more de- C8 - 22µF, 25V electrolytic
1. Power supply tails on I2C bus and memory interfac- C12,C14 - 2.7nF polyster
2. LED indicator panel to indicate ing, please refer to Caller ID construc- C17,C18 - 2.2µF, 16V electrolytic
status/keys pressed tion project in Apr. ’99 issue of EFY. C21,C22 - 220pF ceramic disc
At power ‘on,’ the last-saved audio C23 - 10µF, 50V electrolytic
3. Relay to switch on/off the supply
to the power amplifier or the main unit settings are read by the MCU. In case Miscellaneous:
memory IC cannot be read by the RL1 - 12V, 150 ohm, SPST relay
The following parts are used in re- OEN Pt. No. 57DP-12-1C6
mote systems for VCR, TV, etc: microcontroller, volume LED will blink XTAL - 4MHz quartz crystal
1. Memory (24C02). three times to indicate the problem. The Y - 455kHz, ceramic resonator
2. Remote handset with 12 keys possible reasons could be either a bad - Battery 1.5V, pencil cell
3. IR receiver for remote operation memory IC, or a discontinuity/shorting - IR sensor module
- Remote control handset,
Functionality of these parts is ex- of its tracks, or improper insertion of complete with keyboard
plained below with reference to Figs 1 the IC in its socket. - Connectors for audio input-
The author is the proprietor of GVC Systems, Under the circumstances, the unit output and power supply
will still work, but it will not remem- - 12V DC, 250mA battery
Noida. He can be approached through e-mail
eliminator
at gvc@vsnl.com ber the last settings and will select the
52 ELECTRONICS FOR YOU SEPTEMBER '99

25. CONSTRUCTION
BEVERAGE VENDING
MACHINE CONTROLLER SANI TH
EO
VINAY CHADDHA rants and even in companies. Press a allow compact size, higher reliability,
switch and the machine delivers a hot lower cost and multiple functionalities.
B
everage vending machines are cup of your favourite drink. This tea/coffee/soup vending ma-
commonplace at railway sta- This looks quite a simple operation chine controller uses Freescale’s latest
tions, airports, fast-food restau- but has a very complex logic behind MC908JL16 microcontroller chip. The
it: It involves use of controller is programmable and user-
twelve precision timers friendly. You can set the quantity of
and four counters apart the beverages through a button switch
from physical devices like provided on the front panel of the con-
display, solenoid and mo- troller as per your requirements. Thus,
tor to deliver water and cups of any size can be filled at any
premixed tea/coffee/soup time.
powder in exact quantity
for better taste and in ex- The hardware
act sequence. Fig. 1 shows the block diagram of the
This has become pos- vending machine controller. It com-
sible because of the use of prises the following sections: power
The prototype of beverage vending machine controller
developed by the author microcontrollers, which supply, microcontroller, relays, relay
driver, alphanumeric
display, keyboard and
memory. The power
supply circuit is shown
in Fig. 2.
The control unit
uses low-cost, readily
available components.
The temperature con-
trol section has not
been included in the
design as the parts re-
quired are expensive
and not easily avail-
able. However, a low-
cost thermostat used in
water heaters can be
Fig. 1: Block diagram of the beverage vending machine controller used in the unit.
Power supply. The
relays need 12V DC
and the microcontroller
and memory need 5V
DC for operation.
Bridge rectifier, capaci-
tive filter and regulator
ICs 7812 and 7805 are
the standard parts used
in the power supply.
Microcontroller.
Fig. 2: Power supply circuit We need individually
WWW.EFYMAG.COM ELECTRONICS FOR YOU • OCTOBER 2006 • 77

26. CC O NTS T RTU O N I O N
ONS RUC I CT
MICROCONTROLLER-BASED IL KU
MAR
ACCESS CONTROL SYSTEM
SUN
VINAY CHADDHA* the password data for over ten years. PARTS LIST
The user can modify the password as
S
Semiconductors:
ecurity is a prime concern in our day- well as relay-activation time duration for IC1(U1) - MC68HC705KJ1
to-day life. Everyone wants to be as door entry. This version of software microcontroller
much secure as possible. An access- enables use of the unit even without the IC2 (U2) - ST24C02 I2C EEPROM
control system forms a vital link in a secu- I2C EEPROM. (However, without EEPROM, IC3 (MN1) - MN1280 reset stabiliser
rity chain. The microprocessor-based digi- the password and relay-activation time IC4 (Reg1) - 7805 +5V regulator
tal lock presented here is an access- duration will be reset to default values T1, T2 - BC547 npn transistor
(Q1, Q2)
control system that allows only authorised on interruption of the power supply.) D1, D2 - 1N4007 rectifier diode
persons to access a restricted area. LED1 - Red LED
Hardware details Resistors (all ¼-watt, ± 5% carbon, unless
System overview Fig. 2 shows the access control circuit. Its
stated otherwise):
R1-R6 - 10-kilo-ohm
The block diagram of the access-control main components are a microcontroller, R7-R9 - 1-kilo-ohm
system is shown in Fig. 1. The system I2C memory, power supply, keypad, relay,
Capacitors:
comprises a small electronic unit with a and buzzer.
C1, C2 - 33pF ceramic disk
numeric keypad, which is fixed outside the M ic r ocon t r olle r . The 16-pin
C3, C4,
entry door to control a solenoid-operated MC68HC705KJ1 microcontroller from C6, C7 - 0.1µF ceramic disk
lock. When an authorised person enters a Motorola has the following features: C5 - 10µF, 10V electrolytic
predetermined number (password) via the • Eleven bidirectional input/output Miscellaneous:
keypad, the relay operates for a limited time (I/O) pins
Xtal (Y1) - 4MHz quartz crystal
to unlatch the solenoid-operated lock so the • 1240 bytes of OTPROM program PZ1 (BZ1) - Ceramic piezo buzzer
door can be pushed/pulled open. At the end memory Con1 - Power-supply connector
of preset delay, the relay de-energises and • 64 bytes of user RAM Con2 - 2-pin male/female Berg
the door gets locked again. If the entered • 15-stage multiple-function timer connectors
password is correct the unit gives three Out of eleven I/O pins, seven lines - 7-pin male/female Berg
connectors
small beeps, and if the entered password is have been used for the keyboard, one for
SW1-SW12 - Tactile keyboard switch
wrong it gives a longer beep of one second. the buzzer, one for relay operation, and RL1 (RLY1) - 1C/O, 12V, 250-ohm
The system uses a compact circuitry two (SCL and SDA, i.e. serial clock and miniature relay
built around Motorola’s MC68HC705KJ1 serial data lines) for communication with
microcontroller and a non-volatile I2C I2C EEPROM.
EEPROM (ST24C02) capable of retaining I2C memory. A two-wire serial EEPROM ible 2048-bit (2-kbit) EEPROM is organised
(ST24C02) is as 256x8 bits. It can retain data for more
used in the than ten years. Using just two lines (SCL
circuit to re- and SDA) of the memory, the
tain the pass- microcontroller can read and write the
word and the bytes corresponding to the data required
relay-activa- to be stored.
tion time du- (Note. For details of the microcontroller
ration data. and programming of I2C EEPROM, you may
Data stored refer to the article ‘Caller ID Unit Using
remains in the Microcontroller’ published in April ’99 is-
memory even sue of EFY and the article ‘Remote-con-
after power trolled Audio Processor Using
failure, as the Microcontroller’ published in Sep. ’99 is-
memory en- sue of EFY. For additional data on Motorola
sures reading microcontrollers, refer to EFY-CDs of this
of the latest year’s January and February issues. The
saved settings information pertaining to I2C EEPROM is
by the available on STMicroelectronics’ Website.)
microcontroller. Power supply. The power supply unit
This I 2 C provides a constant 5V supply to the en-
Fig. 1: Block diagram of the access-control system bus-compat- tire unit. This is a conventional circuit us-
50 ELECTRONICS FOR YOU OCTOBER 2002