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HBeonLabs
Off. No. 46, 1st Floor, Kadamba Complex
Gamma-I, Greater Noida (India) - 201308
Contact us:
+91-120-4298000
+91-9212314779
info@hbeonlabs.comtraining@hbeonlabs.com
www. hbeonlabs.com
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REMOTE CONTROLLED DIGITAL CLOCK
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INTRODUCTION
This Project is made up with AT89C51 and the RTC DS1307. It
has a large seven segment display. The standard remote control
is used to change the Time.
Procedure to enter the Time
1-Press power button on the remote to enter new time
2-Press the Numerical buttons to enter the time
3-Press the Menu button to store the new time
This system has a battery backup, so that the Clock will runduring power failure.
Digital clocks typically use the 50 or 60 hertz oscillation of AC
power or a 32,768 hertz crystal oscillator as in a quartz clock tokeep time. Most digital clocks display the hour of the day in 24
hour format; in the United States and a few other countries, a
more commonly used hour sequence is 12 hour format (with
some indication of AM or PM). Some clocks can display either
time mode according to the owner's preference. Emulations of
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analog-style faces often use an LCD screen, and these are also
sometimes described as "digital".
Some people find difficulty in setting the time in some designs
of digital clocks. Therefore in electronic devices where the clock
is not a critical function, often they are not set at all, displaying
the default after powered on, 00:00 or 12:00.
Since they run on electricity, digital clocks must be reset every
time the power is cut off. This is a particular problem with alarm
clocks that have no "battery" backup, because even a very brief
power outage during the night usually results in the clock failing
to trigger the alarm in the morning.
To reduce the problem, many devices designed to operate on
household electricity incorporate a battery backup to maintain
the time during power outages and during times of disconnection
from the power supply. More recently, some devices incorporate
a method for automatically setting the time, such as using abroadcast radio time signal from an atomic clock, getting the
time from an existing satellite television or computer connection,
or by being set at the factory and then maintaining the time from
then on with a quartz movement powered by an internal
rechargeable battery.
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BRIEF INTRODUCTION TO 8051
MICROCONTROLLER:
When we have to learn about a new computer we have to
familiarize about the machine capability we are using, and we
can do it by studying the internal hardware design (devices
architecture), and also to know about the size, number and the
size of the registers.
A microcontroller is a single chip that contains the
processor (the CPU), non-volatile memory for the program
(ROM or flash), volatile memory for input and output (RAM), a
clock and an I/O control unit. Also called a "computer on a
chip," billions of microcontroller units (MCUs) are embedded
each year in a myriad of products from toys to appliances to
automobiles. For example, a single vehicle can use 70 or more
microcontrollers. The following picture describes a general block
diagram of microcontroller.
AT89S52: The AT89S52 is a low-power, high-performance
CMOS 8-bit microcontroller with 8K bytes of in-system
programmable Flash memory. The device is manufactured using
Atmels high-density nonvolatile memory technology and is
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compatible with the industry-standard 80C51 instruction set and
pin out. The on-chip Flash allows the program memory to be
reprogrammed in-system or by a conventional nonvolatilememory programmer. By combining a versatile 8-bit CPU with
in-system programmable Flash on a monolithic chip, the Atmel
AT89S52 is a powerful microcontroller, which provides a highly
flexible and cost-effective solution to many, embedded control
applications. The AT89S52 provides the following standard
features: 8K bytes of Flash, 256 bytes of RAM, 32 I/O lines,
Watchdog timer, two data pointers, three 16-bit timer/counters, a
six-vector two-level interrupt architecture, a full duplex serial
port, on-chip oscillator, and clock circuitry. In addition, the
AT89S52 is designed with static logic for operation down to zero
frequency and supports two software selectable power saving
modes. The Idle Mode stops the CPU while allowing the RAM,
timer/counters, serial port, and interrupt system to continue
functioning. The Power-down mode saves the RAM con-tents
but freezes the oscillator, disabling all other chip functions until
the next interrupt.
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The pin diagram o
unique to microcon
The following a
microcontroller.
1.Internal ROM and2.I/O ports with prog
3.Timers and counter
4.Serial data commun
the 8051 shows all of the i
rollers:
e some of the capabili
AM
ammable pins
ication
put/output pins
ties of 8051
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The 8051 architecture consists of these specific features:
16 bit PC &data pointer (DPTR)
8 bit program status word (PSW)
8 bit stack pointer (SP)
Internal ROM 4k
Internal RAM of 128 bytes.
4 register banks, each containing 8 registers
80 bits of general purpose data memory
32 input/output pins arranged as four 8 bit ports: P0-P3
Two 16 bit timer/counters: T0-T1
Two external and three internal interrupt sources Oscillator andclock circuits.
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RC-5 PROTOCOL
A common used standard protocol for infrared data
communication is the RC5 code, originally developed by Philips.
This code has an instruction set of 2048 different instructions
and is divided into 32 address for different devices the remote
belongs to like TV,VCR etc. with each address having 64
instructions each for different buttons on the remote. Every kind
of equipment uses his own address, and every button has its own
unique code. So this makes it possible to change the volume of
the TV without change the volume of the stereo.
The transmitted code is a data word which consists
of 14 bits and is defined as:
2 start bits for the automatic gain control in the
infrared receiver.
1 toggle bit (change every time when a new button is pressed on
the ir transmitter).
5 address bits for the system address
6 instruction bits for the pressed key
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We used a single remote to control all the devices so
everything except the toggle bit and the and the command
bits are same. We studied the codes for a particular TV
remote
to be used with our devices.
The next challenge was to get something which would detect
these codes so that Atmega 16 microcontroller would read
these codes. The solution is TSOP 1738.
TSOP 1738:-
The TSOP 17XX series are miniaturized receivers for
infrared remote control systems. PIN diode and preamplifier
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are assembled on lead frame, the epoxy package is designed
as IR filter. The demodulated output signal can directly be
decoded by a microprocessor. TSOP 17XX is the standard
IR remote control receiver series, supporting all major
transmission codes. Here XX refers to the frequency of the
infrared carrier signal on which the code is modulated,
which is 38 KHz in our case. It has three pins .GND and
Vcc are connected
to the power supply with VCC as 5V and Vout which
becomes 0V, or GND when the demodulated bit received is
high i.e. 5V and vice versa.
CODING:-
After we have the code transmitted from the remote on
the press of a button to the microcontroller through the
infrared receiver, we wrote a code using CVAVR, a C
compiler that would make a corresponding port of a
microcontroller high when the incoming code matches
the corresponding button code. We read the incoming
code bit by bit by reading the Vout pin of the sensor to a
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port of the microcontroller. To ensure each bit is read
properly, we used a delay of 889 ms, which is the time
period of the demodulated signal which we receive from
the remote and stored it a character array .As we cannot
store a bit directly in an array due to data type miss-match,
we stored 1 in the array whenever the bit was high and vice
versa. Then we compared the part of the code stored which
changes from button to button i.e. the command bit to
distinguish between different button presses and when a
particular code matches, we make corresponding port high,
i.e. give an output of 5V from that port which depends on
the supply voltage we provide to the microcontroller i.e. if
the supply would have been 6V; the high would
correspond to the port giving 6V. The ON OFF condition
of a device. I.e. the device turns on when we press a button
one time and turns off when we press again is fulfilled by
taking care of the toggle bit. We now needed a device
which would turn a equipment on when it receives a
particular voltage from the microcontroller.
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BLOCK DIAGRAM
CIRCUIT DIAGRAM
8051
MICROCONT
ROLLER
POWER
SUPPLY
IR
REMOTE
TSOP
RTC IC
DS 1307
LCD
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COMPONENT LIST
IREMOTE CONTROLLED DIGITAL CLOCK
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HARDWARE DESCRIPTION:
1.POWER SUPPLY:
Name Capacity Quantity
Regulator 78! "
Regulator 78"# "
Capacitor "$% "
Capacitor "$% "
Ceramic Capacitor ##p% #
Dio&e '
(u)* +utton !
' (in +a)e "
8!" ,AT8-.!#/ "
O)cillator ""0!-#m*1 "
LED 8
Re)i)tance ##2 3
Re)i)tance "4 "
Re)i)tance "4 "
T5.O( "
T6 REMOTE "
RTC D."37 "
+TTON CELL 3 6OLT "
RTC CR.TAL "
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Power supplyis a reference to a source of electrical power. A device
or system that supplies electrical or other types of energy to an output
load or group of loads is called a power supply unit or PSU. The
term is most commonly applied to electrical energy supplies, less
often to mechanical ones, and rarely to others. Here in our application
we need a 5v DC power supply for all electronics involved in the
project. This requires step down transformer, rectifier, voltage
regulator, and filter circuit for generation of 5v DC power. Here a
brief description of all the components are given as follows:
TRANSFORMER:
transformer is a device that transfers electrical energy from one
circuit to another through inductively coupled conductors the
transformer's coils or "windings". Except for air-core transformers, the
conductors are commonly wound around a single iron-rich core, or
around separate but magnetically-coupled cores. A varying current in
the first or "primary" winding creates a varying magnetic field in the
core (or cores) of the transformer. This varying magnetic field induces
a varying electromotive force (EMF) or "voltage" in the "secondary"
winding. This effect is called mutual induction.
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If a load is connected to the secondary circuit, electric charge will
flow in the secondary winding of the transformer and transfer energy
from the primary circuit to the load connected in the secondary circuit.
The secondary induced voltage VS, of an ideal transformer, is scaled
from the primary VP by a factor equal to the ratio of the number of
turns of wire in their respective windings:
By appropriate selection of the numbers of turns, a transformer thus
allows an alternating voltage to be stepped up by making NSmore
than NP or stepped down, by making it
BASIC PARTS OF A TRANSFORMER
In its most basic form a transformer consists of:
A primary coil or winding.
A secondary coil or winding.
A core that supports the coils or windings.
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Refer to the transformer circuit in figure as you read the following
explanation: The primary winding is connected to a 60-hertz ac
voltage source. The magnetic field (flux) builds up (expands) and
collapses (contracts) about the primary winding. The expanding and
contracting magnetic field around the primary winding cuts the
secondary winding and induces an alternating voltage into the
winding. This voltage causes alternating current to flow through the
load. The voltage may be stepped up or down depending on the design
of the primary and secondary windings.
THE COMPONENTS OF A TRANSFORMER
Two coils of wire (called windings) are wound on some type of core
material. In some cases the coils of wire are wound on a cylindrical or
rectangular cardboard form. In effect, the core material is air and the
transformer is called an AIR-CORE TRANSFORMER. Transformers
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According to the con
established by Benjami
today, current is assum
the positive to the ne
conductor nearly alway
In the vast majority of
current flow is irrelev
conventional model is r
In the diagrams below,
the diamond is positive
negative, current flows
along the red (positive
supply terminal via the
When the input connect
connected to the rightc
ventional model of current
Franklin and still followed b
d to flow through electrical
ative pole. In actuality, fre
flow from the negative to t
applications, however, the a
ant. Therefore, in the discu
tained.
when the input connected to
and the input connected to t
from the upper supply ter
path to the output, and retu
lue(negative) path.
ed to the leftcorner is negati
orner is positive, current flow
flow originally
most engineers
conductors from
e electrons in a
e positivepole.
tualdirection of
sion below the
he leftcorner of
e rightcorner is
inal to the right
rns to the lower
ve, and the input
s from the lower
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supply terminal to the
returns to the uppersu
In each case, the upper
output negative. Since t
circuit not only produc
provide what is someti
is, it permits normal
batteries have been ins
from a DC power so
equipment from potenti
Prior to availability of
was always constructed
a single four-termina
connected in the bridge
right along the red path to
ply terminal via the bluepath
right output remains positiv
is is true whether the input i
s a DC output from an AC i
es called "reverse polarity
unctioning of DC-powered
talled backwards, or when t
urce have been reversed,
l damage caused by reverse p
integrated electronics, such
from discrete components. S
l component containing t
configuration became a stan
the output, and
.
and lower right
AC or DC, this
nput, it can also
rotection". That
quipment when
he leads (wires)
nd protects the
olarity.
bridge rectifier
ince about 1950,
e four diodes
ard commercial
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component and is no
ratings.
OUTPUT SMOOTHI
For many applications,
full-wave bridge serves
addition of a capacito
supplies an output of
"pulsating" magnitude (
The function of this csmoothing capacitor) i
rectified AC output
explanation of 'smoot
impedance path to the
voltage across, and A
technical terms, any d
available with various vol
G
especially with single phas
to convert an AC input into
may be desired because t
fixed polarity but continuo
ee diagram above).
pacitor, known as a reservto lessen the variation in
voltage waveform from t
ing' is that the capacitor
C component of the output,
current through, the resisti
op in the output voltage an
age and current
AC where the
DC output, the
he bridge alone
usly varying or
ir capacitor (oror 'smooth') the
e bridge. One
provides a low
reducing the AC
ve load. In less
d current of the
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bridge tends to be canceled by loss of charge in the capacitor. This
charge flows out as additional current through the load. Thus the
change of load current and voltage is reduced relative to what would
occur without the capacitor. Increases of voltage correspondingly
store excess charge in the capacitor, thus moderating the change in
output voltage / current.
The simplified circuit shown has a well-deserved reputation for being
dangerous, because, in some applications, the capacitor can retain a
lethal charge after the AC power source is removed. If supplying a
dangerous voltage, a practical circuit should include a reliable way to
safely discharge the capacitor. If the normal load cannot be guaranteed
to perform this function, perhaps because it can be disconnected, the
circuit should include a bleeder resistor connected as close as practical
across the capacitor. This resistor should consume a current large
enough to discharge the capacitor in a reasonable time, but small
enough to minimize unnecessary power waste.
Because a bleeder sets a minimum current drain, the regulation of the
circuit, defined as percentage voltage change from minimum to
maximum load, is improved. However in many cases the
improvement is of insignificant magnitude.
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of a bridge, the bridge diodes must be sized to withstand the current
surge that occurs when the power is turned on at the peak of the AC
voltage and the capacitor is fully discharged. Sometimes a small series
resistor is included before the capacitor to limit this current, though in
most applications the power supply transformer's resistance is already
sufficient.
Output can also be smoothed using a choke and second capacitor. The
choke tends to keep the current (rather than the voltage) more
constant. Due to the relatively high cost of an effective choke
compared to a resistor and capacitor this is not employed in modern
equipment.
Some early console radios created the speaker's constant field with the
current from the high voltage ("B +") power supply, which was then
routed to the consuming circuits, (permanent magnets were then too
weak for good performance) to create the speaker's constant magnetic
field. The speaker field coil thus performed 2 jobs in one: it acted as a
choke, filtering the power supply, and it produced the magnetic field
to operate the speaker.
REGULATOR IC (78XX)
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It is a three pin IC used as a voltage regulator. It converts unregulated
DC current into regulated DC current.
Normally we get fixed output by connecting the voltage regulator at
the output of the filtered DC (see in above diagram). It can also be
used in circuits to get a low DC voltage from a high DC voltage (for
example we use 7805 to get 5V from 12V). There are two types of
voltage regulators 1. fixed voltage regulators (78xx, 79xx) 2. variable
voltage regulators(LM317) In fixed voltage regulators there is another
classification 1. +ve voltage regulators 2. -ve voltage regulators
POSITIVE VOLTAGE REGULATORS This include 78xx voltage
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regulators. The most commonly used ones are 7805 and 7812. 7805
gives fixed 5V DC voltage if input voltage is in (7.5V, 20V).
The Capacitor Filter
The simple capacitor filter is the most basic type of power supply
filter. The application of the simple capacitor filter is very limited. It is
sometimes used on extremely high-voltage, low-current power
supplies for cathode-ray and similar electron tubes, which require very
little load current from the supply. The capacitor filter is also used
where the power-supply ripple frequency is not critical; this frequency
can be relatively high. The capacitor (C1) shown in figure 4-15 is a
simple filter connected across the output of the rectifier in parallel
with the load.
Full-wave rectifier with a capacitor filter.
When this filter is used, the RC charge time of the filter capacitor (C1)
must be short and the RC discharge time must be long to eliminate
ripple action. In other words, the capacitor must charge up fast,
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preferably with no discharge at all. Better filtering also results when
the input frequency is high; therefore, the full-wave rectifier output is
easier to filter than that of the half-wave rectifier because of its higher
frequency.
For you to have a better understanding of the effect that filtering has
on Eavg, a comparison of a rectifier circuit with a filter and one without
a filter is illustrated in views A and B of figure 4-16. The output
waveforms in figure 4-16 represent the unfiltered and filtered outputs
of the half-wave rectifier circuit. Current pulses flow through the load
resistance (RL) each time a diode conducts. The dashed line indicates
the average value of output voltage. For the half-wave rectifier, Eavgis
less than half (or approximately 0.318) of the peak output voltage.
This value is still much less than that of the applied voltage. With no
capacitor connected across the output of the rectifier circuit, the
waveform in view A has a large pulsating component (ripple)
compared with the average or dc component. When a capacitor is
connected across the output (view B), the average value of output
voltage (Eavg) is increased due to the filtering action of capacitor C1.
UNFILTERED
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The rate of charge for the capacitor is limited only by the resistance of
the conducting diode, which is relatively low. Therefore, the RC
charge time of the circuit is relatively short. As a result, when the
pulsating voltage is first applied to the circuit, the capacitor charges
rapidly and almost reaches the peak value of the rectified voltage
within the first few cycles. The capacitor attempts to charge to the
peak value of the rectified voltage anytime a diode is conducting, and
tends to retain its charge when the rectifier output falls to zero. (The
capacitor cannot discharge immediately.) The capacitor slowly
discharges through the load resistance (RL) during the time the
rectifier is non-conducting.
The rate of discharge of the capacitor is determined by the value of
capacitance and the value of the load resistance. If the capacitance and
load-resistance values are large, the RC discharge time for the circuit
is relatively long.
A comparison of the waveforms shown in figure 4-16 (view A and
view B) illustrates that the addition of C1 to the circuit results in an
increase in the average of the output voltage (Eavg) and a reduction in
the amplitude of the ripple component (Er) which is normally present
across the load resistance.
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Now, let's consider a complete cycle of operation using a half-wave
rectifier, a capacitive filter (C1), and a load resistor (RL). As shown in
view A of figure 4-17, the capacitive filter (C1) is assumed to be large
enough to ensure a small reactance to the pulsating rectified current.
The resistance of RLis assumed to be much greater than the reactance
of C1 at the input frequency. When the circuit is energized, the diode
conducts on the positive half cycle and current flows through the
circuit, allowing C1 to charge. C1 will charge to approximately the
peak value of the input voltage. (The charge is less than the peak value
because of the voltage drop across the diode (D1)). In view A of the
figure, the charge on C1 is indicated by the heavy solid line on the
waveform. As illustrated in view B, the diode cannot conduct on the
negative half cycle because the anode of D1 is negative with respect to
the cathode. During this interval, C1 discharges through the load
resistor (RL). The discharge of C1 produces the downward slope as
indicated by the solid line on the waveform in view B. In contrast to
the abrupt fall of the applied ac voltage from peak value to zero, the
voltage across C1 (and thus across RL) during the discharge period
gradually decreases until the time of the next half cycle of rectifier
operation. Keep in mind that for good filtering, the filter capacitor
should charge up as fast as possible and discharge as little as possible.
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the anode of the diode exceeds the voltage on the charge remaining on
C1. The charge on C1 is the cathode potential of the diode. When the
potential on the anode exceeds the potential on the cathode (the charge
on C1), the diode again conducts, and C1 begins to charge to
approximately the peak value of the applied voltage.
After the capacitor has charged to its peak value, the diode will cut off
and the capacitor will start to discharge. Since the fall of the ac input
voltage on the anode is considerably more rapid than the decrease on
the capacitor voltage, the cathode quickly become more positive than
the anode, and the diode ceases to conduct.
Operation of the simple capacitor filter using a full-wave rectifier is
basically the same as that discussed for the half-wave rectifier.
Referring to figure 4-18, you should notice that because one of the
diodes is always conducting on. either alternation, the filter capacitor
charges and discharges during each half cycle. (Note that each diode
conducts only for that portion of time when the peak secondary
voltage is greater than the charge across the capacitor.)
Figure 4-18. - Full-wave rectifier (with capacitor filter).
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Another thing to keep in mind is that the ripple component (Er) of the
output voltage is an ac voltage and the average output voltage (Eavg) is
the dc component of the output. Since the filter capacitor offers a
relatively low impedance to ac, the majority of the ac component
flows through the filter capacitor. The ac component is therefore
bypassed (shunted) around the load resistance, and the entire dc
component (or Eavg) flows through the load resistance. This statement
can be clarified by using the formula for XC in a half-wave and full-
wave rectifier. First, you must establish some values for the circuit.
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As you can see from the
rectifier, you reduce the
calculations, by doubling the
impedance of the capacitor b
frequency of the
one-half. This
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allows the ac componen
a result, a full-wave rec
a half-wave rectifier. R
capacitor with respect t
action. Since
the largest possible cap
Remember, also, that th
If load resistance is m
average value of outpu
time constant is a direc
therefore, the rate of ca
the current through the
rapid the discharge of t
of output voltage. For
seldom used with recti
load current. Using the
full-wave or bridge rec
increased ripple freque
filter capacitor.
t to pass through the capacito
ifier output is much easier to
member, the smaller the XCo
the load resistance, the bette
citor will provide the best filt
load resistance is an import
de small, the load current i
t voltage (Eavg) decreases. T
t function of the value of th
acitor voltage discharge is a
load. The greater the load c
he capacitor, and the lower t
this reason, the simple ca
ier circuits that must supply
simple capacitive filter in co
tifier provides improved filte
cy decreases the capacitive
more easily. As
ilter than that of
the filter
the filtering
ring.
nt consideration.
creases, and the
e RC discharge
load resistance;
irect function of
urrent, the more
e average value
acitive filter is
relatively large
njunction with a
ring because the
reactance of the
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CIRCUIT DIAGRAM OF POWER SUPPLY
T-SOP 17 SERIES:
DESCRIPTION
The TSOP17.. series are miniaturized receivers for infrared remote control
systems. PIN diode and preamplifier are assembled on lead frame, the epoxy
package is designed as IR filter. The demodulated output signal can directly be
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decoded by a microprocessor. TSOP17.. is the standard IR remote control
receiver series, supporting all major transmission codes.
FEATURES
Photo detector and preamplifier in one package
Internal filter for PCM frequency Improved shielding against electrical field disturbance
TTL and CMOS compatibility
Output active low
Low power consumption
High immunity against ambient light
Continuous data transmission possible (up to 2400 bps)
Suitable burst length .10 cycles/burst
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Display Section:
LIQUID CRYSTL DIS!LY
T*e li9ui& 5 cry)tal &i)play ,LCD/ con)i)t o% a li9ui& cry)tal material
,normally organic %or LCD:)/ t*at ;ill %lo; li4e a li9ui&
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n&er &ar4 con&ition)> it ;oul& a re%lector can
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T*e a ;*ic* are limite& to num t*ere t*e
LED mu)t
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T*e LCD u)e& *ere *a)
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T*ere are t;o ?ery important regi)ter) in)i&e t*e LCD0 T*e R. pin i)
u)e& %or t*eir )election a) %ollo;) 0I% R. > t*en in)truction
comman& co&e regi)ter i) )electe& > allo;ing t*e u)er to )en& t*e
comman& )uc* a) clear &i)play> cur)or at *ome> etc0 I% R. " t*e &ata
regi)ter i) )electe&> allo;ing t*e u)er to )en& &ata to
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D0 ) D*:
T*e 8 D D7> are u)e& to )en& in%ormation to t*e
LCD or rea& t*e content) o% t*e LCD) internal regi)ter)0
To &i)play letter) an& num ;e )en& A.CII co&e) %or t*e letter) A5
> a51> an& 5- to t*e)e pin) ;*ile ma4ing R. "0
T*ere are al)o in)truction comman& co&e) t*at can
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!IN DESCRI!TION +OR LCD
!i
n
Sy,
-ol
I&O Desc.iption
" 6)) 55 Groun&
# 6cc 55 H!6 po;er )upply
3 6EE 55 (o;er )upply to control contra)t
' R. I R. %or comman& regi)ter> R." %or
&ata regi)ter
! RJ I RJH %or ;rite> RJH" %or rea&
E IJO Ena
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! .*i%t &i)play le%t
7 .*i%t &i)play le%t
8 Di)play o%%> cur)or o%%
A Di)play o%%> cur)or on
C Di)play on> cur)or o%%
E Di)play on
F Di)play on> cur)or
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'ORIN%:
T*e inter%ace u)e&
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eight bit transfer. The "Enable" Clock is used to initiate the data
transfer within the LCD.
Sending parallel data as either four or eight bits are the two primary
modes of operation. While there are secondary considerations and
modes, deciding how to send the data to the LCD is most critical
decision to be made for an LCD interface application.
Eight bit mode is best used when speed is required in an application
and at least ten I/O pins are available. Four bit mode requires a
minimum of six bits. To wire a microcontroller to an LCD in four bit
mode, just the top four bits (DB4-7) are written to.
The "RS" bit is used to select whether data or an instruction is being
transferred between the microcontroller and the LCD. If the Bit is set,
then the byte at the current LCD "Cursor" Position can be read or
written. When the Bit is reset, either an instruction is being sent to the
LCD or the execution status of the last instruction is read back
(whether or not it has completed).
Rea&ing Data
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groun&e& RJ pin ;*ic* mean) ;e are not retrie?ing any &ata %rom
LCD0
The LCD can be thought of as a "Teletype" display because in normal
operation, after a character has been sent to the LCD, the internal
"Cursor" is moved one character to the right. The "Clear Display" and
"Return Cursor and LCD to Home Position" instructions are used to
reset the Cursor's position to the top right character on the display.
To move the Cursor, the "Move Cursor to Display" instruction is used.
For this instruction, bit 7 of the instruction byte is set with the
remaining seven bits used as the address of the character on the LCD
the cursor is to move to. These seven bits provide 128 addresses,
which matches the maximum number of LCD character addresses
available.
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Eight programmable characters are available and use codes 0x000 to
0x007. They are programmed by pointing the LCD's "Cursor" to the
Character Generator RAM
The last aspect of the LCD to discuss is how to specify a contrast
voltage to the Display. I typically use a potentiometer wired as a
voltage divider. This will provide an easily variable voltage between
Ground and Vcc, which will be used to specify the contrast (or
"darkness") of the characters on the LCD screen. You may find that
different LCDs work differently with lower voltages providing darker
characters in some and higher voltages do the same thing in others
CIRCUIT DIAGRAM OF LCD INTERFACING
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Optional in&u)trial temperature range 5'C to H8!C
Available in 8-pin DIP or SOIC Underwriters Laboratory (UL)
recognized
PIN DESCRIPTION
6CC 5 (rimary (o;er .upply
P"> P# 5 3#07841 Cry)tal Connection
6+AT 5 H36 +attery Input
GND 5 Groun&
.DA 5 .erial Data
.CL 5 .erial Cloc4
.QJOT 5 .9uare a?eJOutput Dri?er
DESCRIPTION
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T*e D."37 .erial Real5Time Cloc4 i) a lo;5po;er>
%ull
&ay> &ate> mont*> an& year in%ormation0 T*e en& o% t*e mont* &ate i)
automatically a&Bu)te& %or mont*) ;it* %e;er t*an 3" &ay)> inclu&ing
correction) %or leap year0 T*e cloc4 operate) in eit*er t*e #'5*our or
"#5*our %ormat ;it* AMJ(M in&icator0 T*e D."37 *a) a
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VISION
The Vision IDE is, for most developers, the easiest way to
create embedded system programs. This chapter describes
commonly used Vision features and explains how to use them.
General Remarks and Concepts
Before we start to describe how to use Vision, some general
remarks, common to many screens1 and to the behavior of the
development tool, are presented. In our continuous effort todeliver best-in-class development tools, supporting you in your
daily work, Vision has been built to resemble the look-and-feel
of widespread applications. This approach decreases your
learning curve, such that
you may start to work with Vision right away.
Based on the concept of windows:
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Vision windows can be re-arranged, tiled, and attached to
other screen areas or windows respectively It is possible to drag
and drop windows, objects, and variables
A Context Menu, invoked through the right mouse button, is
provided for most objects. You can use keyboard shortcuts and
define your own shortcuts. You can use the abundant features of
a modern editor. Menu items and Toolbar buttons are greyed out
when not available in the Current context.
Graphical symbols are used to resemble options, to mark
unsaved changes, or reveal objects not included into the project.
Status Bars display context-driven information.You can
associate Vision to third-party tools
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The Project Windows area is that part of the screen in which,
by default, the Project Window, Functions Window, Books
Window, and Registers Window are displayed.
Within the Editor Windows area, you are able to change the
source code, view performance and analysis information, and
check the disassembly code.
The Output Windows area provides information related to
debugging, memory, symbols, call stack, local variables,
commands, browse information, and find in files results.
If, for any reason, you do not see a particular window and have
tried displaying/hiding it several times, please invoke the default
layout of Vision through the Window Reset Current
Layout Menu.
Positioning Windows
The Vision windows may be placed onto any area of the
screen, even outside of the Vision frame, or to another physical
screen.
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Click and hold the Title Bar1 of a window with the left mouse
button
Drag the window to the preferred area, or onto the preferred
control, and release the mouse button
Please note, source code files cannot be moved outside of the
Editor Windows2.\ Invoke the Context Menu of the windows
Title Bar to change the docking attribute of a window object. Insome cases, you must perform this action before you can drag
and drop the window.
Vision displays docking helper controls3, emphasizing the area
where the window will be attached. The new docking area is
represented by the section highlighted in blue. Snap the window
to the Multiple Document Interface (MDI) or to a Windows area
by moving the mouse over the preferred control.
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eil so7ta.e con9e.ts te C;co$es into te Intel e co$e
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