off. no. 46, 1st floor, kadamba complex gamma-i, greater...
TRANSCRIPT
HBeonLabs
Off. No. 46, 1st Floor, Kadamba Complex Gamma-I, Greater Noida (India) - 201308
Contact us:
+91-120-4298000 +91-9212314779
www. hbeonlabs.com
CHAPTER 1 INTRODUCTION & COMPONENTS
INTRODUCTION
“ Automatic College Bell (AT89S52 & DS1307)”.
This Project takes over the task of Ringing of the Bell in Colleges. It replaces the Manual Switching of the Bell in the College. It has an Inbuilt Real Time Clock (DS1307) which track over the Real Time. When this time Equals to the Bell Ringing time, then the Relay for the Bell is switched On. The Bell Ringing time can be Edited at any Time, so that it can be used at Normal Class Timings as well as Exam Times. The Real Time Clock is displayed on LCD display. The Microcontroller AT89S52 is used to control all the Functions, it get the time through the keypad and store it in its Memory. And when the Real time and Bell time get equal then the Bell is switched on for a predetermined time.
This is very wonderful project to control the working of College Bell. These bell are equipped with the CPU which control the bell.
1. 8051 Microcontroller
2. DS1307
3. LCD .
4.Relay
In this project we try to give the same prototype as Manual Switching Bell with the help of programmed micro-controller . We are using ATMEL microcontroller 8051 to control all the function as CPU. Microcontroller controls the ringing of bell
WHAT IS EMBEDDED TECHNOLOGY
Embedded technology is software or hardware that is hidden embedded
in a large device or system. It typically refers to a fixed function device,
as compared with a PC, which runs general purpose application.
Embedded technology is nothing new. It all around us and has been for
years. An early example of embedded technology is the engine control
unit in a car, which measures what setting to give the engine. Your
coffee maker has embedded technology in the form of a
microcontroller, which is what tells it to make the coffee at 6 a.m. the
vending machine has it too. Overall, billions of devices woven into
everyday life use embedded technology. In the past embedded
technology existed in standalone device vending machines and copiers
that did their jobs with little regard for what went on around them,. But
as technology has learned to connect device to the internet and to each
other, embedded technology potential has grown. Suddenly it is and
what actions those connections let them perform. Cell phone companies
figured that out a long time ago, which is why cell phones are cheap and
the service, plans are expensive. It is not the phone itself that matters,
but the connectivity to a vast network of other phones, other people
and the internet. Until you download software that lets you find a local
restaurant or mange your finances. Let say you make freezers the big,
expensive kind that grocery stores buy. You sell ne and you are done
with that customer. When it brakes the customer calls a service person,
who probably comes from somewhere other than your company. But let
us say that freezer knows that it is about to go on the fritz. Let say three
refrigerator alerts the customer before it breaks. Better yet, let us say
the freezer alerts the manufacturer and you are able to send a service
person to do preventative work and save a lot of haagen- dazs from
melting. Embedded technology allows all of that to happen. You, the
freezer company have
transformed yourself from a product company to product and services
company. The possibilities go beyond that programming device to
communicate with businesses can eliminate the need for costly call
centers. Copy machines that can order their own replacement cartridges
will save businesses time and money. Remember, the fact the
technology is embedded is not what important, and neither is the
device.
APPLICATIONS
Telecom
• Mobile phone systems (handsets and base stations), modems,
routers
• Automotive application
• Braking system, Traction control, Airbag release system,
Management units, and Steer-by-wire systems.
Domestic application
• Dishwasher, television, washing machines, microwave ovens,
Video recorders, Security system, Garage door controllers,
Calculators, Digital watches, VCRs, Digital cameras, Remote
Controls, Treadmills
Robotic
• Fire fighting robot, Automatic floor cleaner, robotic arm
Aerospace application
• Flight control system, Engine controllers, Autopilots, Passenger
entertainment system
Medical equipment
• Anesthesia monitoring system, ECG monitors, Pacemakers, Drug
delivery systems, MRI scanners
Defense system
• Radar systems, Fighter aircraft flight control system, Radio system,
Missile guidance systems
Office automation
• Laser printers, Fax machines, Pagers, Cash registers, Gas pumps,
Credit /Debit card readers, Thermostats, Grain analyzers.
COMPONENTS
LIST OF COMPONENTS USED
AUTOMATIC COLLEGE BELL
Name Capacity Quantity Codes
Regulators 7805 1 U1
7812 1 U3
Capacitor 1000µf 1 C1
Capacitor 10µf 1 C2
Ceramic
Capacitor
22pf 2 C3,C4
Diode 4 D1,D2,D3,D4
Push Button 5 SW1,SW2,SW3,SW4,SW7
40 Pin Base 1 U2
8 Pin Base 1 U4
8051 (AT89S52) 1 U2
RTC DS1307 1 U4
Oscillator 11.0592mhz 1 XTL1
Oscillator 32.768khz 1 XTL2
LCD 16*2 1 LCD
LED 3 D5,D6,D7
Resistance 220Ω 6 R4,R1,R6,R7,R5,R8
Resistance 1k 1 R3
Resistance 10k 4 R2,R9,R11,R10
Battery 3V 1 BT1
Transistors BC547 3 Q1,Q2,Q3
BUZZER 1 BUZ
3V cell holder
base
BT1
2 pin SCREW
connector
1 J1
COMPONENT DESCRIPTION
MICRO-CONTROLLER 8051 DESCRIPTION
The IC 8051 is a low-power; high-performance CMOS 8-bit
microcomputer with 4K bytes of Flash programmable and erasable read
only memory (PEROM). The device is manufactured using Atmel’s high-
density nonvolatile memory technology and is compatible with the
industry-standard MCS-51 instruction set and pin out. The on-chip Flash
allows the program memory to be reprogrammed in-system or by a
conventional nonvolatile memory programmer. By combining a versatile
8-bit CPU with Flash on a monolithic chip, the Atmel IC 8051 is a
powerful microcomputer which provides a highly-flexible and cost-
effective solution to many embedded control applications. The IC 8051
provides the following standard features: 4K bytes of Flash, 128 bytes of
RAM, 32 I/O lines, two 16-bit timer/counters, a five vector two-level
interrupt architecture, full duplex serial port, on-chip oscillator and clock
circuitry. In addition, the IC 8051 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.
Transformer 12-0-12 1
Printed PCB 1
Relays 2 RL1,RL2
2pin connectors male 2 J5,J6
16pin connector male 1 LCD
Pin Description of the 8051
1234567891011121314151617181920
4039383736353433323130292827262524232221
P1.0P1.1P1.2P1.3P1.4P1.5P1.6P1.7RST
(RXD)P3.0(TXD)P3.1
(T0)P3.4(T1)P3.5
XTAL2XTAL1
GND
(INT0)P3.2(INT1)P3.3
(RD)P3.7(WR)P3.6
VccP0.0(AD0)P0.1(AD1)P0.2(AD2)P0.3(AD3)P0.4(AD4)P0.5(AD5)P0.6(AD6)P0.7(AD7)EA/VPPALE/PROGPSENP2.7(A15)P2.6(A14)P2.5(A13)P2.4(A12)P2.3(A11)P2.2(A10)P2.1(A9)P2.0(A8)
8051(8031)
Figure No. 1.1: Pin Diagram of 8051
PROCESSOR
A processor is an electronic device capable of manipulating data in a way
specified by a sequence of instructions.
INSTRUCTIONS
Instructions in a computer are binary numbers just like data. Different
numbers, when read and executed by a processor, cause different things
to happen. The instructions are also called opcodes or machine codes.
Different bit patterns activate or deactivate different parts of the
processing core. Every processor has its own instruction set varying in
number, bit pattern and functionality.
PROGRAM
The sequence of instructions is what constitutes a program. The
sequence of instructions may be altered to suit the application.
ASSEMBLY LANGUAGE
Writing and understanding such programs in binary or hexadecimal
form is very difficult ,so each instructions is given a symbolic notation in
English language called as mnemonics. A program written in mnemonics
Form is called an assembly language program. But it must be converted
into machine language for execution by processor.
ASSEMBLER
An assembly language program should be converted to machine
language for execution by processor. Special software called ASSEMBLER
converts a program written in mnemonics to its equivalent machine
opcodes.
HIGH LEVEL LANGUAGE
A high level language like C may be used to write programs for
processors. Software called compiler converts this high level language
program down to machine code. Ease of programming and portability.
PIN DESCRIPTION
VCC (Pin 40)
Provides voltage to the chip . +5V
GND (Pin 20)
Ground
XTAL1 (Pin 19) and XTAL2 (Pin 18)
Crystal Oscillator connected to pins 18, 19.Two capacitors of 30pF value.
Time for one machine cycle:11.0592/12=1.085 µ secs
RST (Pin 9)
RESET pin
1.Active high. On applying a high pulse to this pin, microcontroller will
reset and terminate all activities.
2.INPUT pin
3.Minimum 2 machine cycles required to make RESET
4.Value of registers after RESET
External Access: EA 31
•Connected to VCC for on chip ROM
•Connected to Ground for external ROM containing the code Input Pin
Program Store Enable: PSEN 29
•Output Pin
•In case of external ROM with code it is connected to the OE pin of the
ROM
Address Latch Enable: ALE 30
• Output Pin. Active high
•In case of external ROM ,ALE is used to de multiplex (PORT 0) the
address and data bus by connecting to the G pin of 74LS373 chip
I/O Port Pins and their Functions:
•Four ports P0,P1,P2,P3 with 8 pins each, making a total of 32
input/output pins
•On RESET all ports are configured as output. They need to be
programmed to make them function as inputs
PORT 0
•Pins 32-39
•Can be used as both Input or Output
•External pull up resistors of 10K need to be connected
•Dual role: 8051 multiplexes address and data through port 0 to save
pins .AD0-AD7
•ALE is used to de multiplex data and address bus
PORT 1
•Pins 1 through 8
•Both input or output
•No dual function
•Internal pull up registers
•On RESET configured as output
PORT 2
•Pins 21 through 28
•No external pull up resistor required
•Both input or output
•Dual Function: Along with Port 0 used to provide the 16-Bit address for
external memory. It provides higher address A8-A16
PORT 3
•Pins 10 through 17
•No external pull up resistors required
PROCESSOR ARCHITECTURE
Block Diagram
CPU
On-chip RAM
On-chip ROM for program code
4 I/O Ports
Timer 0
Serial PortOSC
Interrupt Control
External interrupts
Timer 1
Timer/Counter
Bus Control
TxD RxDP0 P1 P2 P3
Address/Data
Counter Inputs
Figure No. 1.3: Block Diagram of Microcontroller
ALU
The Arithmetic Logic Unit (ALU) performs the internal arithmetic
manipulation of data line processor. The instructions read and executed
by the processor decide the operations performed by the ALU and also
control the flow of data between registers and ALU. Operations
performed by the
ALU are Addition , Subtraction , Not , AND , NAND , OR , NOR , XOR ,
Shift Left/Right , Rotate Left/right , Compare etc. Some ALU supports
Multiplication and Division. Operands are generally transferred from
two registers or from one register and memory location to ALU data
inputs. The result of the operation is the placed back into a given
destination register or memory location from ALU output.
REGISTERS
Registers are the internal storage for the processor. The number of
registers varies significantly between processor architectures.
•WORKING REGISTERS
Temporary storage during ALU Operations and data transfers.
•INDEX REGISTERS
Points to memory addresses.
•STATUS REGISTERS
Stores the current status of various flags denoting conditions resulting
from various operations.
•CONTROL REGISTERS
Contains configuration bits that affect processor operation and the
operating modes of various internal subsystems.
Memory Organization
Program Memory
Data Memory
The right half of the internal and external data memory spaces available on Atmel’s Flash microcontrollers. Hardware configuration for accessing up to 2K bytes of external RAM. In this case, the CPU executes from internal Flash. Port 0 serves as a multiplexed address/data bus to the RAM, and 3 lines of Port 2 are used to page the RAM. The CPU generates RD and WR signals as needed during external RAM accesses. You can assign up to 64K bytes of external data memory. External data memory addresses can be either 1 or 2 bytes wide. One-byte addresses are often used in conjunction with one or more other I/O lines to page the RAM. Two-byte addresses can also be used, in which case the high address byte is emitted at Port 2.
Internal data memory addresses are always 1 byte wide, which implies an address space of only 256 bytes. However, the addressing modes for internal RAM can in fact accommodate 384 bytes. Direct addresses higher than 7FH access one memory space, and indirect addresses higher than 7FH access a different memory space. Thus, the Upper 128 and SFR space occupying the same block of addresses, 80H through FFH, although they are physically separate entities. The lowest 32 bytes are grouped into 4 banks of 8 registers. Program instructions call out these registers as R0 through R7. Two bits in the Program Status Word (PSW) select which register bank is in use. This architecture allows more efficient use of code space, since register instructions are shorter than instructions that use direct addressing.
Programming Status Word:
The Instruction Set
All members of the Atmel microcontroller family execute the same instruction set. This instruction set is optimized for 8- bit control applications and it provides a variety of fast addressing modes for accessing the internal RAM to facilitate byte operations on small data structures. The instruction set provides extensive support for 1-bit variables as a separate data type, allowing direct bit manipulation in control and logic systems that require Boolean processing. The following overview of the instruction set gives a brief description of how certain instructions can be used.
Program Status Word
The Program Status Word (PSW) contains status bits that reflect the current state of the CPU. The PSW, shown in Figure 11, resides in SFR space. The PSW contains the Carry bit, the Auxiliary Carry (for BCD operations), the tworegister bank select bits, the Overflow flag, a Parity bit, and two user-definable status flags. The Carry bit, in addition to serving as a Carry bit in arithmetic operations, also serves as the “Accumulator” for a number of Boolean operations.
The bits RS0 and RS1 select one of the four register banks shown in Figure 8. A number of instructions refer to these RAM locations as R0 through R7. The status of the RS0 and RS1 bits at execution time determines which of the four banks is selected. The Parity bit reflects the number of 1s in the Accumulator: P=1 if the Accumulator contains an odd number of 1s, and P=0 if the Accumulator contains an even number of 1s.
Thus, the number of 1s in the Accumulator plus P is always even. Two bits in the PSW are uncommitted and can be used as general purpose status flags.
Addressing Modes
The addressing modes in the Flash microcontroller instruction set are as follows.
Direct Addressing
In direct addressing, the operand is specified by an 8-bit address field in the instruction. Only internal data RAM and SFRs can be directly addressed.
Indirect Addressing
In indirect addressing, the instruction specifies a register that contains the address of the operand. Both internal and external RAM can be indirectly addressed. The address register for 8-bit addresses can be either the Stack Pointer or R0 or R1 of the selected register bank. The address register for 16-bit addresses can be only the 16-bit data pointer register, DPTR.
Register Instructions
The register banks, which contain registers R0 through R7, can be accessed by instructions whose opcodes carry a 3- bit register specification. Instructions that access the registers this way make efficient use of code, since this mode eliminates an address byte. When the instruction is executed, one of the eight registers in the selected bank is accessed. One of four banks is selected at execution time by the two bank select bits in the PSW.
Register-Specific Instructions
Some instructions are specific to a certain register. For example, some instructions always operate on the Accumulator, so no address byte is needed to point to it. In these cases, the opcode itself points to the correct register. Instructions that refer to the Accumulator as A assemble as Accumulator-specific opcodes.
Indexed Addressing
Program memory can only be accessed via indexed addressing. This addressing mode is intended for reading look-up tables in program memory. A 16-bit base register (either DPTR or the Program Counter) points to the base of the table, and the Accumulator is set up with the table entry number. The address of the table entry in program memory is
formed by adding the Accumulator data to the base pointer. Another type of indexed addressing is used in the “case jump” instruction. In this case the dest ination address of a jump instruction is computed as the sum of the base pointer and the Accumulator data.
•SRAM
Volatile, fast, low capacity, expensive, requires lesser external support circuitry.
•DRAM
Volatile, relatively slow, highest capacity needs continuous refreshing. Hence
require external circuitry.
•OTP ROM
One time programmable, used for shipping in final products.
•EPROM
Erasable programmable, UV Erasing, Used for system development and
debugging.
•EEPROM
Electrically erasable and programmable, can be erased programmed in- circuit,
Used for storing system parameters.
•FLASH
Electrically programmable & erasable, large capacity, organized as sectors.
BUSES
A bus is a physical group of signal lines that have a related function. Buses allow
for the transfer of electrical signals between different parts of the processor
Processor buses are of three types:
•Data bus
•Address bus
•Control bus
CONTROLLER LOGIC
Processor brain decodes instructions and generate control signal for various sub
units. It has full control over the clock distribution unit of processor.
I/O Peripherals
The I/O devices are used by the processor to communicate with the external
world
•Parallel Ports.
•Serial Ports.
•ADC/DAC.
About Keil uVision 3
Keil Software to provide you with software development tools for 8051
based microcontrollers. With the Keil tools, you can generate
embedded applications for virtually every 8051 derivative. The
supported microcontrollers are listed in the µVision
Device Database™. The Keil Software 8051 development tools are
designed for the professional software developer, but any level of
programmer can use them to get the most out of the 8051
microcontroller architecture.
Keil software converts the C-codes into the Intel Hex code.
A view of Keil uVision 3
8051 Burner Software
51 BURNER provides you with software burning tools for 8051 based
Microcontrollers in there Flash memory. The 51 BURNER tools, you can burn
AT89SXXXX series of ATMEL microcontrollers .
DESCRIPTION OF
DESCRIPTION OF REAL –TIME CLOCKTIME CLOCK
DETAILED DESCRIPTION The DS1307 is a low-power clock/calendar with 56 bytes of batteryclock/calendar provides seconds, minutes, hours, day, date, month, and year information. The date at the end of the month is automatically adjusted foincluding corrections for leap year. The DS1307 operates as a slave device on the I2C bus. Access is obtained by implementing a START condition and providing a device identification code followed by a register address. SubSTOP condition is executed. When VCC falls below 1.25 x VBAT, the device terminates an access in progress and resets the device address counter. Inputs to the device will not be recognized at this time to prevent erroneous data from being written to the device from an outtolerance system. When VCC falls below VBAT, the device switches into a lowbackup mode. Upon power-up, the device switches from battery to VCC when VCC is greater
DETAILED DESCRIPTION
power clock/calendar with 56 bytes of batteryclock/calendar provides seconds, minutes, hours, day, date, month, and year information. The date at the end of the month is automatically adjusted for months with fewer than 31 days, including corrections for leap year. The DS1307 operates as a slave device on the I2C bus. Access is obtained by implementing a START condition and providing a device identification code followed by a register address. Subsequent registers can be accessed sequentially until a STOP condition is executed. When VCC falls below 1.25 x VBAT, the device terminates an access in progress and resets the device address counter. Inputs to the device will not be
to prevent erroneous data from being written to the device from an outtolerance system. When VCC falls below VBAT, the device switches into a low
up, the device switches from battery to VCC when VCC is greater
power clock/calendar with 56 bytes of battery-backed SRAM. The clock/calendar provides seconds, minutes, hours, day, date, month, and year information. The
r months with fewer than 31 days, including corrections for leap year. The DS1307 operates as a slave device on the I2C bus. Access is obtained by implementing a START condition and providing a device identification
sequent registers can be accessed sequentially until a STOP condition is executed. When VCC falls below 1.25 x VBAT, the device terminates an access in progress and resets the device address counter. Inputs to the device will not be
to prevent erroneous data from being written to the device from an out-of-tolerance system. When VCC falls below VBAT, the device switches into a low-current battery-
up, the device switches from battery to VCC when VCC is greater
than VBAT +0.2V and recognizes inputs when VCC is greater than 1.25 x VBAT. The block diagram in Figure 1 shows the main elements of the serial RTC.
OSCILLATOR CIRCUIT The DS1307 uses an external 32.768kHz crystal. The oscillator circuit does not require any external resistors or capacitors to operate. Table 1 specifies several crystal parameters for the external crystal. Figure 1 shows a functional schematic of the osciwith the specified characteristics, the startup time is usually less than one second. CLOCK ACCURACY The accuracy of the clock is dependent upon the accuracy of the crystal and the accuracy of the match between the capacitive load of the oscillator circuit and the capacitive load for which the crystal was trimmed. Additional error will be added by crystal frequency drift caused by temperature shifts. External circuit noise coupled into the oscillator circuit may resultclock running fast. Refer to Application Note 58: Clocks for detailed information
han VBAT +0.2V and recognizes inputs when VCC is greater than 1.25 x VBAT. The block diagram in Figure 1 shows the main elements of the serial RTC.
The DS1307 uses an external 32.768kHz crystal. The oscillator circuit does not require any external resistors or capacitors to operate. Table 1 specifies several crystal parameters for the external crystal. Figure 1 shows a functional schematic of the oscillator circuit. If using a crystal with the specified characteristics, the startup time is usually less than one second.
The accuracy of the clock is dependent upon the accuracy of the crystal and the accuracy of the pacitive load of the oscillator circuit and the capacitive load for which the
crystal was trimmed. Additional error will be added by crystal frequency drift caused by temperature shifts. External circuit noise coupled into the oscillator circuit may resultclock running fast. Refer to Application Note 58: Crystal Considerations with Dallas Real
for detailed information
han VBAT +0.2V and recognizes inputs when VCC is greater than 1.25 x VBAT. The block
The DS1307 uses an external 32.768kHz crystal. The oscillator circuit does not require any external resistors or capacitors to operate. Table 1 specifies several crystal parameters for the
llator circuit. If using a crystal with the specified characteristics, the startup time is usually less than one second.
The accuracy of the clock is dependent upon the accuracy of the crystal and the accuracy of the pacitive load of the oscillator circuit and the capacitive load for which the
crystal was trimmed. Additional error will be added by crystal frequency drift caused by temperature shifts. External circuit noise coupled into the oscillator circuit may result in the
Crystal Considerations with Dallas Real-Time
RTC AND RAM ADDRESS MAP Table 2 shows the address map for the DS1307 RTC and RAM registers. The RTC registers are located in address locations 00h to 07h. The RAM registers are located in address locations 08h to 3Fh. During a multibyte access, when the address pointer reaches 3Fh, the end of RAM space, it wraps around to location 00h, the beginning of the clock space.
CLOCK AND CALENDAR The time and calendar information is obtained by reading the appropriate register bytes. Table 2 shows the RTC registers. The time and calendar are set or initialized by writing the appropriate register bytes. The contents of the time and calendar registers are in the BCD format. The day-of-week register increments at midnight. Values that correspond to the day of week are user-defined but must be sequential (i.e., if 1 equals Sunday, then 2 equals Monday, and so on.) Illogical time and date entries result in undefined operation. Bit 7 of Register 0 is the clock halt (CH) bit. When this bit is set to 1, the oscillator is disabled. When cleared to 0, the oscillator is enabled. On first application of power to the device the time and date registers are typically reset to 01/01/00 01 00:00:00 (MM/DD/YY DOW HH:MM:SS). The CH bit in the seconds register will be set to a 1. The clock can be halted whenever the timekeeping functions are not required, which minimizes current (IBATDR). The DS1307 can be run in either 12-hour or 24-hour mode. Bit 6 of the hours register is defined as the 12-hour or 24-hour mode-select bit. When high, the 12-hour mode is selected. In the 12-hour mode, bit 5 is the AM/PM bit with logic high being PM. In the 24-hour mode, bit 5 is the second 10-hour bit (20 to 23 hours). The hours value must be re-entered whenever the 12/24-hour mode bit is changed. When reading or writing the time and date registers, secondary (user) buffers are used to prevent errors when the internal registers update. When reading the time and date registers, the user buffers are synchronized to the internal registers on any I2C START. The time information is read from these secondary registers while the clock continues to run. This eliminates the need to re-read the registers in case the internal registers update during a read. The divider chain is reset whenever the seconds register is written. Write transfers occur on the I2C acknowledge from the DS1307. Once the divider chain is reset, to avoid rollover issues, the remaining time and date registers must be written within one second.
VOLAGE REGULATOR
Voltage regulator ICs are available with fixed (typically 5, 12 and 15V) or variable
output voltages. The maximum current they can pass also rates them. Negative
voltage regulators are available, mainly for use in dual supplies. Most regulators
include some automatic protection from excessive current (over load protection)
and overheating (thermal protection). Many of fixed voltage regulator ICs has 3
leads. They include a hole for attaching a heat sink if necessary.
Figure No. 1.5: 7805 Voltage Regulator
DESCRIPTION
These voltage regulators are monolithic circuit integrated circuit designed as
fixed voltage regulators for a wide variety of applications including local, on card
regulation. These regulators employ internal current limiting, thermal shutdown,
and safe-area compensation. With adequate heat sinking they can deliver output
current in excess of 1.0 A. Although designed primarily as a fixed voltage
regulator, these devices can be used with external components to obtain
adjustable voltage and current.
FEATURES
•Output current in Excess of 1.0 A
•No external component required
•Internal thermal overload protection
•Internal short circuit current limiting
•Output transistor safe-area compensation
•Output voltage offered in 2% and 4% tolerance
•Available I n surface mount D2PAK and standard 3-lead transistor packages
•Previous commercial temperature range has been extended to a junction
temperature range of -40 degree C to +125 degree C.
LCD DISPLAY
DESCRIPTION OF LCD DISPLAY
This is the first interfacing example for the Parallel Port. We will start with
something simple. This example doesn't use the Bi-directional feature found on
newer ports, thus it should work with most, if not all Parallel Ports. It however
doesn't show the use of the Status Port as an input. These LCD Modules are very
common these days, and are quite simple to work with, as all the logic required to
run them is on board.
SCHEMATIC DIAGRAM
Figure No. 1.8: Schematic Diagram of LCD Display
CIRCUIT DESCRIPTION
Above is the quite simple schematic. The LCD panel's Enable and Register Select
is connected to the Control Port. The Control Port is an open collector / open
drain output. While most Parallel Ports have internal pull-up resistors, there is a
few which don't. Therefore by incorporating the two 10K external pull up
resistors, the circuit is more portable for a wider range of computers, some of
which may have no internal pull up resistors. We make no effort to place the
Data bus into reverse direction. Therefore we hard wire the R/W line of the LCD
panel, into write mode. This will cause no bus conflicts on the data lines. As a
result we cannot read back the LCD's internal Busy Flag which tells us if the LCD
has accepted and finished processing the last instruction. This problem is
overcome by inserting known delays into our program. The 10k Potentiometer
controls the contrast of the LCD panel. Nothing fancy here. As with all the
examples, I've left the power supply out. You can use a bench power supply set to
5v or use an onboard +5 regulator. Remember a few de-coupling capacitors,
especially if you have trouble with the circuit working properly. The 2 line x 16
character LCD modules are available from a wide range of manufacturers and
should all be compatible with the HD44780. The diagram to the right shows the
pin numbers for these devices. When viewed from the front, the left pin is pin 16
and the right pin is pin 1.
Figure No. 1.9: LCD Display
Figure 1 shows how to inte ace 7-seg display to a microcontroller. Now we create
a lookup table containing the seven segment pattern to display the corresponding
hex digits. e.g. consider we have to display '1' from the above figure we come to
know that turning ON segment B & C will show '1' on the 7-seg display so P2.1 &
P2.2 should be LOGIC 0 whereas rest of the pins should be LOGIC 1. FIGURE 2
shows the lookup table for CA display.
POWER SUPPLY
BRIDGE RECTIFIER
Bridge rectifier circuit consists of four diodes arranged in the form of a bridge as
shown in figure.
OPERATION
During the positive half cycle of the input supply, the upper end A of the
transformer secondary becomes positive with respect to its lower point B. This
makes Point1 of bridge Positive with respect to point 2. The diode D1 & D2
become forward biased & D3 & D4 become reverse biased. As a result a current
starts flowing from point1, through D1 the load & D2 to the negative end. During
negative half cycle, the point2 becomes positive with respect to point1. Diodes D1
& D2 now become reverse biased. Thus a current flow from point 2 to point1.
TRANSFORMER
Transformer is a major class of coils having two or more windings usually
wrapped around a common core made from laminated iron sheets. It has two cols
named primary and secondary. If the current flowing through primary is
fluctuating, then a current will be inducted into the secondary winding. A steady
current will not be transferred from one coil to other coil.
Transformers are of two types:
1.Step up transformer
2.Step down transformer
In the power supply we use step down transformer. We apply 220V AC on the
primary of step down transformer. This transformer step down this voltages to 6V
AC. We Give 6V AC to rectifier circuit, which convert it to 5V DC.
DIODE
The diode is a p-n junction device. Diode is the component used to control the
flow of the current in any one direction. The diode widely works in forward bias.
Diode When the current flows from the P to N direction. Then it is in forward
bias. The Zener diode is used in reverse bias function i.e. N to P direction. Visually
the identification of the diode`s terminal can be done by identifying he
silver/black line. The silver/black line is the negative terminal (cathode) and the
other terminal is the positive terminal (cathode).
APPLICATION
•Diodes: Rectification, free-wheeling, etc
•Zener diode: Voltage control, regulator etc.
•Tunnel diode: Control the current flow, snobbier circuit, etc
RESISTORS
The flow of charge through any material encounters an opposing force similar in
many respects to mechanical friction .this opposing force is called resistance of
the material .in some electric circuit resistance is deliberately introduced in form
of resistor. Resistor used fall in three categories , only two of which are color
coded which are metal film and carbon film resistor .the third category is the wire
wound type ,where value are generally printed on the vitreous paint finish of the
component. Resistors are in ohms and are represented in Greek letter omega,
looks as an upturned horseshoe. Most electronic circuit require resistors to make
them work properly and it is obliviously important to find out something about
the different types of resistors available. Resistance is measured in ohms, the
symbol for ohm is an omega ohm. 1 ohm is quite small for electronics so
resistances are often given in kohm and Mohm.
Resistors used in electronics can have resistances as low as 0.1 ohm or as high as
10 Mohm.
FUNCTION
Resistor restrict the flow of electric current, for example a resistor is placed in
series with a light-emitting diode(LED) to limit the current passing through the
LED.
TYPES OF RESISTORS
FIXED VALUE RESISTORS
It includes two types of resistors as carbon film and metal film .These two types
are explained under
1. CARBON FILM RESISTORS
During manufacture, at in film of carbon is deposited onto a small ceramic rod.
The resistive coating is spiraled away in an automatic machine until the resistance
between there two ends of the rods is as close as possible to the correct value.
Metal leads and end caps are added, the resistors is covered with an insulating
coating and finally painted with colored bands to indicate the resistor value
Figure No. 1.15: Carbon Film Resistors
Another example for a Carbon 22000 Ohms or 22 Kilo-Ohms also known as 22K
at 5% tolerance: Band 1 = Red, 1st digit Band 2 = Red, 2nd digit Band 3 = Orange,
3rd digit, multiply with zeros, in this case 3 zero's Band 4 = Gold, Tolerance, 5%
METAL FILM RESISTORS
Metal film and metal oxides resistors are made in a similar way, but can be made
more accurately to within ±2% or ±1% of their nominal vale there are some
difference in performance between these resistor types, but none which affects
their use in simple circuit.
WIRE WOUND RESISTOR
A wire wound resistor is made of metal resistance wire, and because of this, they
can be manufactured to precise values. Also, high wattage resistors can be made
by using a thick wire material. Wire wound resistors cannot be used for high
frequency circuits. Coils are used in high frequency circuit. Wire wound resistors
in a ceramic case, strengthened with special cement. They have very high power
rating, from 1 or 2 watts to dozens of watts. These resistors can become
extremely hot when used for high power application, and this must be taken into
account when designing the circuit.
TESTING
Resistors are checked with an ohm meter/millimeter. For a defective resistor the
ohm-meter shows infinite high reading.
CAPACITORS
In a way, a capacitor is a little like a battery. Although they work in completely
different ways, capacitors and batteries both store electrical energy. If you have
read How Batteries Work , then you know that a battery has two terminals. Inside
the battery, chemical reactions produce electrons on one terminal and absorb
electrons at the other terminal.
BASIC
Like a battery, a capacitor has two terminals. Inside the capacitor, the terminals
connect to two metal plates separated by a dielectric. The dielectric can be air,
paper, plastic or anything else that does not conduct electricity and keeps the
plates from touching each other. You can easily make a capacitor from two pieces
of aluminum foil and a piece of paper. It won't be a particularly good capacitor in
terms of its storage capacity, but it will work.
In an electronic circuit, a capacitor is shown like this:
Figure No. 1.17: Symbol of Capacitor
When you connect a capacitor to a battery, here’s what happens:
•The plate on the capacitor that attaches to the negative terminal of the battery
accepts electrons that the battery is producing.
•The plate on the capacitor that attaches to the positive terminal of the battery
loses electrons to the battery.
TESTING
To test the capacitors, either analog meters or specia
l digital meters with the specified function are used. The non-electrolyte capacitor
can be tested by using the digital meter.
Multi – meter mode : Continuity Positive probe : One end Negative probe :
Second end Display : `0`(beep sound occur) `OL` Result : Faulty OK
LED
LED falls within the family of P-N junction devices. The light emitting diode (LED) is
a diode that will give off visible light when it is energized. In any forward biased
P-N junction there is, with in the structure and primarily close to the junction, a
recombination of hole and electrons. This recombination requires that the energy
possessed by the unbound free electron be transferred to another state. The
process of giving off light by applying an electrical source is called
electroluminescence.
LED is a component used for indication. All the functions being carried out are
displayed by led .The LED is diode which glows when the current is being flown
through it in forward bias condition. The LEDs are available in the round shell and
also in the flat shells. The positive leg is longer than negative leg.
CHAPTER 2 LITERATURE REVIEW
PREHISTORY: 8048
In fact, it should have started with chapter -2, the invention of microprocessor.
Intel introduced a single-chip processor, the 4004, in 1971. It was a 4-bit
microprocessor, with whopping processing speed of 100 thousand operations per
second, and was meant for an electronic calculator. There is a lot of 4-bit
processing in calculators, especially if the software is based on BCD arithmetics.
Later Intel introduced the 8-bitter 8008 and it's grown-up brother - the famous
8080 (which then was perfected by an ex-Intel employee as Zilog Z80, one of the
best 8-bit microprocessors of all times). In 1976, Intel introduced its first
microcontroller, 8048. It integrated the processing core with code and data
memory and certain peripherals. The code memory was a 1kB mask ROM (defined
by the last metallisation mask during the chip processing) or EPROM (after all,
Intel invented EPROM), the data memory was 64 bytes of RAM (including the 8-
level stack and two pages of eight general purpose registers). Besides general-
purpose I/O (see below), peripherals included a timer and an external interrupt
(plus the necessary interrupt system). Although the 8048 is clearly an 8-bit
architecture, it is said to be an ancestor of the 4-bit 4004 rather than the 8080.
Also it is said to bear remarkable similarities to Fairchild F8 microprocessor.
Today, it is hard to say whether something of this is true, but one thing is sure,
the 8048 has a couple of strange features. Using four of its general purpose
input/output ports, and adding one or more 8243-type chip - and the I/O expand
into another four 4-bit ports. This expansion has not only support in the hardware
- dedicated pins on 8048 - but also in the instruction set, having dedicated
instructions for I/O operations (including AND and OR(!)) via the expander.
The 8048 already had a lot of useful features known well to 8051-users: external
code memory support; external data memory support (inherently only 256 bytes
addressed indirectly by R0 and R1 as there is no 16 bit pointer register such as the
DPTR in 8051 - the 8051 inherited this 8-bit external data access);
quasibidirectional I/O ports. Maximum clock is 11MHz, but an instruction cycle
takes 15 oscillator clocks. The "A" version (advanced) introduced powerdown
mode There were multiple variations of the 8048 around, mostly with different
numbering, but generally denoted as the MCS-48 family. 8048 itself denoted a
mask-ROM part, 8748 an EPROM part - windowed (CERDIP - erasable) for
development, and unwindowed (PDIP) OTP. The romless part was a bit
surprisingly marked 8035 (probably most of the parts sold as romless were parts
with unusable ROM, due to error in the "programmed" firmware). There was a
low-cost version with reduced pin count and omitted some of the features as
8021, and versions with more ROM and RAM as 8049 (2kB ROM/128B RAM) and
8050 (4kB ROM/256B RAM); with ROMless versions as 8039 and 8040; and 8049
had also an EPROM version 8749 (the funny thing is, that 8749 came in 1981, one
year after 8051/8751). 8048's were second sourced by a number of
manufacturers, including NEC, Toshiba, and were cloned also behind the then iron
curtain in Czechoslovakia (Tesla MHB8048/8035) and USSR. Application specific
versions of 8048 were also built quite early, with adding of various peripherals,
such as 8-bit ADC in 8022 and a parallel-bus slave interface in 8041/8042. The
MCS-48 family was used in a quite wide range of applications. One of the first
applications of 8048 was in a gaming console (Magnavox Odyssey2), but there
were also more "serious" applications, for example in one of the first car engine
"computerized" control units. But the biggest hit came when IBM decided to use
8048 in its original PC keyboard. Although in the AT keyboard IBM used the
(presumably cheaper) 6805, it used 8042 as a co-processor on the mainboard,
communicating with the keyboard. The 8042 is still present in almost each and
every PC even today, but don't search for a chip with "8042" on it - it is integrated
in the chipset. It may come as a surprise to somebody, but thanks to this fact the
8048 with its derivatives is most probably the most widespread microcontroller at
all.
As in the 70s there were no pdf-s and no world-wide web, datasheets and other
documentation is hardly available over the internet. I believe Intel will give out a
copy if one really wants it (there is a "literature request" form at their "museum"
pages). However, there seems to be a couple of enthusiastic people, one of the
maintaining a wonderful document called “Grokking the MCS-48 System” at
http://home.mnet-online.de/al/mcs-48/mcs-48.pdf .
8051: THE CLASSICS
In 1980, Intel introduced the successor to 8048, the 8051. Intel made sure that
the transition from the already successful model will be as smooth as possible.
Architecturally, the 8051 is an extension to 8048. Almost every feature and
resource of 8048 is present in 8051 in same or superior form. 4kB ROM and 128B
RAM on chip. Pin compatibility was not maintained, but it was not a real issue.
Software compatibility is not binarywise but source-wise, but that is also
acceptable. The preliminary datasheet read: "Enhanced MCS-48 Architecture".
The extensions included code and data memory extended to 64kB with
appropriate support in instruction set and registers (DPTR), relative conditional
and unconditional jumps (conditionals and DJNZ were constrained within a 256-
byte page in 8048), four register banks instead of two, "unlimited" stack (8048
had stack limited to 16 bytes), multiple and divide instructions. As for peripherals,
second timer was added and both were extended to 16 bits with multiple modes
(including 8-bit autoreload mode), and an UART (which was a luxury that many
lower-end microcontrollers didn't have even a couple of years ago). The raw clock
frequency did not increase considerably, being 12MHz, but an instruction cycle is
12 clocks now. Similarly to 8048, also the 8051 had variants, but there was no
cut-down "low-cost" version (presumably because of the cost of ROM/RAM and
the DIP40 package went low enough). The romless version was 8031 and the
EPROM version was 8751. The "extended" version - 8052 (with 8032 and 8752)
came 3 years later and featured besides 8kB ROM and 256B RAM also an extra
16-bit timer. An unusual chip was the 8052AH-BASIC, which according to Intel was
"software-onsilicon version of the 8052 microcontroller with a BASIC interpreter
on-chip in 8K ROM". The whole family was eventually called MCS-51 and was
manufactured in NMOS, since 1986 in CMOS. Intel provided all the needed initial
tools and support with the 8051 - assembler, application notes, example
software, in-circuit emulator. Some of the appnotes and software still can be
found on Intel's webpages and are of excellent quality. The basic datasheet set -
dubbed in the community as "the bible" - is still THE reference source of
information on 8051 and its derivatives, even today. So, Intel did its job,
providing everything needed to make 8051 successful, and the rest is history.
THE BIRDS ARE OUT OF
THE NEST
Similar to 8048, also the 8051 has been licensed to various manufacturers
worldwide. Some of the early adopters include Philips, Signetics, MHS (Matra) and
Siemens. Most of these companies don't exist any more, some have been taken
over, others have been renamed; but most of them still manufacture some
derivative of 8051. The licensees started to make fully compatible models.
Naturally, they took over also the datasheets, for example the "bible" is better
used in the Philips version, which is a verbatim copy of the Intel version, except
that it is a true searchable pdf, while the Intel is a scanned copy of paper
document, unsearchable. More than that, the manufacturers took over the
annoying practice of Intel to include in datasheets only the specific differences to
the "bible", very confusing for the newbies (but there are opinions on this, some
of the users consider this arrangement better than having huge datasheets
containing all the “common” details). The manufacturers published their own
appnotes, which all together form a huge knowledge base and code library, but...
due to competition it is scattered across the manufacturers' sites, an another
confusing fact for the newbies. Later, the manufacturers rolled out their own
derivatives and variants with varying marking - there is no real standard in it
(although there are some idiosyncrasies present in the marking of most
manufacturers). All types of modifications described in the following chapters
were applied; but the compatibility to the original 8051 was usually maintained.
This, together with the availability of second-, third-,...,35th-,...-source of 8051 is
the true source of its immortality.
EMBEDDED IN EMBEDDED
Intel and the licensees soon realized that 8051 is a nice core that can be
embedded in various ASIC chips to perform setup and control tasks. Typically, the
resources of the ASIC are mapped as external data memory, as if the ASIC would
be connected to a conventional 8051 chip. This approach allows to use an
unmodified core, which speeds up the chip development and decreases the
chance for error; also the ASIC could be breadboard-prototyped in this form
easily. As an example, Intel produced 80C51SL, a descendant of 8042. Philips has
a line of 8051-based teletext controllers. In a particular USB webcamera, the chip
interfacing the CCD and USB was controlled by an embedded 8051. There are
probably much more examples around, but most of them never get public. In
spite of this, the 8051 in this form is produced probably in much higher volumes
than as general-purpose microcontrollers.
EXTRAS
Besides application-specific, also general purpose derivatives have been
introduced by Intel and the licensees, with enhanced features and increased code
and data memories. In contrast with the ASICs mentioned above, these chips tend
to implement the extra features in the core itself, acces allows faster code as SFRs
are accessed by all the instructions using direct addressing (mov, logic), and some
of them by the bit-manipulation instructions, too. One of the first such derivative
by Intel was the 80C51FA, which introduced the programmable counter array
(PCA) (and was a 8052 otherwise). It was intended for automotive applications
(brake control). Soon, FB and FC continued, with more and more code memory.
80C51RA/RB/RC followed, with added "internal external" data memory. These
were the basis for the today's 89C51RD2 "sub-family", produced by Philips, Atmel
(as ex-Temic), SST and Winbond.
FAT BOYS: 16-BIT EXTENSIONS
When the 8051 was accepted widely enough, some of the applications started to
grow and soon required more power than the 8051 even with enhancements
could provide. There were 16-bit microcontrollers around (e.g. Intel had it's
80C196 line), but it seemed a good idea to provide a more natural migration path
by creating a 16-bit version of 8051. Intel addressed the problem by introducing
80C251. It went all the way to achieve compatibility - it was able to run 8051
binary code (being able to switch to native 16-bit 251-mode) and had a package
pin-compatible with 8051. It was not a big success, most probably for bad market
timing (although it is second sourced by Temic/Atmel). Philips on the other hand
employed source-compatibility for its XA family, which seems to be adequate for
most of the applications, where legacy code has to be maintained or parallel
development with 8051 is needed; and poses little constraint on the chip design
itself. All in all, the 16-bit versions of 8051 gained far less popularity than the
8051 and are less widespread.
FLASH FOR THE MASSES
In the 90s, Atmel introduced a derivative of 8051 with Flash code memory,
enabling fast erasure and reprogramming. It enabled to use the production-grade
chip in development, and enabled the chips used in the product to be
reprogrammed when upgrade or a bugfix was needed, cutting down costs. It
brought down the 8051 to the masses - the small "garage" companies and
hobbyists. Besides that, Atmel introduced also 89C2051 with decreased pin count
(and price).This was a smart move, the chip proved to be extremely popular in
many small applications. Today, virtually all manufacturers produce 8051
derivatives with Flash, most of them able to be programmed via some few-pin
serial interface (called in-situ programming (ISP), SPI-style or UART-style) and the
higher-end versions also able to reprogram themselves (in-application
programming, IAP). MaskROM and EPROM - windowed or OTP - seems to become
extinct, at least in the mainstream applications.
NEED FOR SPEED
The need for higher processing power, addressed unsuccessfully by the 16-bit
versions, has been solved by introducing the high speed derivatives of 8051. The
original 12-clock instruction cycle scheme is obviously inefficient and also the
technology progressed enough to achieve higher clock rates than the original
12MHz. The first derivative addressing this in a radical way is the now legendary
Dallas DS80C320. It featured a 4-clocker core with incompatible timing, and could
be clocked as high as 33MHz. Unfortunately, it was produced as ROMless only.
The following step was taken by Cygnal, where a single-clock core has been
developed. In the top-range models, the clocking is as high as 100MHz, being the
fastest 8051s around.
Today, there are many 8051 derivatives with sped-up cores available. They can be
divided into two groups: the 6-clockers (e.g. the 8xC51RD2) and 2-clockers
(Philips LPC9xx) have the same number of instruction cycle per instruction as the
original; while the 4-clockers and singleclockers are incompatible in this way,
requiring recalculation of timing loops if used.
WHERE IS IT GOING?
The 8051 is a sound mcu core with rich history. However, it seems that it is
already over its peak, although it might take quite a lot of time until it will be
completely replaced by most modern microcontrollers. So we now have
superfast 8051 derivatives with loads of internal FLASH and RAM. ISP and IAP
seems to be the standard these days. There are the 8051s built around advanced
analog circuits, mainly high resolution ADC. There are derivatives suitable for
extreme applications – high temperature, radiation hardened. There are softcores
around, tuned up, and even open source. There is a wealth of knowledge and
experience, however, it is scattered around and the newbies tend to get the
easier path - competing 8-bit microcontrollers usually do have a single-stop
information resource site, so this knowledge and experience seems to die out as
the "old boys" retire gradually. The price difference between the high-end 8-
bitters and the much more powerful low-end 32-bit RISCs (such as the ARMs)
seems to decrease rapidly and will change eventually, as the 32-bitters are
becoming the standard in all but the least demanding applications.So there is
perhaps still a need for the 8051s, but this need is decreasing and 8051s life cycle
is slowly approaching its end.
CHAPTER 3
P.C.B. DESIGNING & WORKING
P.C.B. DESIGNING
P.C.B. LAYOUT
The entire circuit can be easily assembled on a general purpose P.C.B. board
respectively. Layout of desired diagram and preparation is first and most
important operation in any printed circuit board manufacturing process. First of
all layout of component side is to be made in accordance with available
components dimensions. The following points are to be observed while forming
the layout of P.C.B.
1.Between two components, sufficient space should be maintained.
2.High voltage/max dissipated components should be mounted at sufficient
distance from semiconductor and electrolytic capacitors.
3.The most important points are that the components layout is making proper
compromise with copper side circuit layout. Printed circuit board (P.C.B.s) is used
to avoid most of all the disadvantages of conventional breadboard. These also
avoid the use of thin wires for connecting the components; they are small in size
and efficient in performance.
PREPARING CIRCUIT LAYOUT
First of all the actual size circuit layout is to be drawn on the copper side of the
copper clad board. Then enamel paint is applied on the tracks of connection with
the help of a shade brush. We have to apply the paints surrounding the point at
which the connection is to be made. It avoids the disconnection between the leg
of the component and circuit track. After completion of painting work, it is
allowed to dry.
DRILLING
After completion of painting work, holes 1/23inch(1mm) diameter are drilled at
desired points where we have to fix the components.
ETCHING
The removal of excess of copper on the plate apart from the printed circuit is
known as etching. From this process the copper clad board wit printed circuit is
placed in the solution of FeCl with 3-4 drops of HCL in it and is kept so for about
10 to 15 minutes and is taken out when all the excess copper is removed from the
P.C.B. After etching, the P.C.B. is kept in clean water for about half an hour in
order to get P.C.B. away from acidic, field, which may cause poor performance of
the circuit. After the P.C.B. has been thoroughly washed, paint is removed by soft
piece of cloth dipped I thinner or turbine. Then P.C.B. is checked as per the layout,
now the P.C.B. is ready for use.
SOLDERING
Soldering is the process of joining two metallic conductor the joint where two
metal conductors are to be join or fused is heated with a device called soldering
iron and then as allow of tin and lead called solder is applied which melts and
converse the joint. The solder cools and solidifies quickly to ensure is good and
durable connection between the jointed metal converting the joint solder also
present oxidation.
SOLDERING AND DESOLDERING TECHIQUES:
These are basically two soldering techniques.
•Manual soldering with iron.
•Mass soldering.
SOLDERING WITH IRON
The surface to be soldered must be cleaned & fluxed. The soldering iron switched
on and bellowed to attain
soldering temperature. The solder in form of wire is allied hear the component
to be soldered and heated with iron. The surface to be soldered is filled, iron is
removed and joint is cold without disturbing.
SOLDER JOINT ARE SUPPOSED TO
1.Provide permanent low resistance path.
2.Make a robust mechanical link between P.C.B. and leads of components.
3.Allow heat flow between component, joining elements and P.C.B.
4.Retain adequate strength with temperature variation. The following precaution
should be taken while soldering:
1.Use always an iron plated copper core tip for soldering iron.
2.Slightly for the tip with a cut file when it is cold.
3.Use a wet sponge to wipe out dirt from the tip before soldering instead of
asking the iron.
4.Tighten the tip screw if necessary before iron is connected to power supply.
5.Clean component lead and copper pad before soldering.
6.Apply solder between component leads, P.C.B. pattern and tip of soldering iron.
7.Iron should be kept in contact with the joint for 2-3 seconds only instead of
keeping for very long or very small time.
8.Use optimum quantity of solder
WORKING
This project uses a stepper motor to control the position of solar energy
collectors, using Intel 8051 .
PROBLEM FACED
•First problem that was in making the circuit of SOLAR TRACER that, it
is difficult to match time with rotation of stepper motor & LCD.
•Second problem is faced due to redundancy in handling the rotation
of STEPPER MOTOR
•We have to take extra care while soldering 2 line LCD
•During soldering, many of the connection become short cktd. So we
desolder the connection and did soldering again.
•A leg of the crystal oscillator was broken during mounting. So it has to
be replaced.
•LED`s get damaged when we switched ON the supply so we replace it
by the new one.
TROUBLESHOOT
•Care should be taken while soldering. There should be no shorting of
joints.
•Proper power supply should maintain.
•Project should be handled with care since IC are delicate
•Component change and check again circuit
