Atmega32 development board IntroductionArduino is a single-board microcontroller, intended to make the application of interactive objects or environments more accessible.[1] The hardware consists of an open-source hardware board designed around an 8-bit Atmel AVR microcontroller, or a 32-bit Atmel ARM. Pre-programmed into the on-board microcontroller chip is a boot loader that allows uploading programs into the microcontroller memory without needing a chip (device) programmer.Arduino boards can be purchased pre-assembled or as do-it-yourself kits. Hardware design information is available for those who would like to assemble an Arduino by hand. It was estimated in mid-2011 that over 300,000 official Arduinos had been commercially produced,[2] and in 2013 that 700,000 official boards were in users' hands.[3]An Arduino board consists of an Atmel 8-bit AVR microcontroller with complementary components to facilitate programming and incorporation into other circuits. An important aspect of the Arduino is the standard way that connectors are exposed, allowing the CPU board to be connected to a variety of interchangeable add-on modules known as shields. Some shields communicate with the Arduino board directly over various pins, but many shields are individually addressable via an IC serial bus, allowing many shields to be stacked and used in parallel. Official Arduinos have used the mega AVR series of chips, specifically the ATmega8, ATmega168, ATmega328, ATmega1280, and ATmega2560. A handful of other processors have been used by Arduino compatibles. Most boards include a 5volt linear regulator and a 16MHz crystal oscillator (or ceramic resonator in some variants), although some designs such as the LilyPad run at 8MHz and dispense with the onboard voltage regulator due to specific form-factor restrictions. An Arduino's microcontroller is also pre-programmed with a boot loader that simplifies uploading of programs to the on-chip flash memory, compared with other devices that typically need an external programmer. This makes using an Arduino more straightforward by allowing the use of an ordinary computer as the programmer.At a conceptual level, when using the Arduino software stack, all boards are programmed over an RS-232 serial connection, but the way this is implemented varies by hardware version. Serial Arduino boards contain a level shifter circuit to convert between RS-232-level and TTL-level signals. Current Arduino boards are programmed via USB, implemented using USB-to-serial adapter chips such as the FTDI FT232. Some variants, such as the Arduino Mini and the unofficial Boarduino, use a detachable USB-to-serial adapter board or cable, Bluetooth or other methods. (When used with traditional microcontroller tools instead of the Arduino IDE, standard AVR ISP programming is used.)The Arduino board exposes most of the microcontroller's I/O pins for use by other circuits. The Diecimila, Duemilanove, and current Uno provide 14 digital I/O pins, six of which can produce pulse-width modulated signals, and six analog inputs. These pins are on the top of the board, via female 0.10-inch (2.5mm) headers. Several plug-in application shields are also commercially available.The Arduino Nano, and Arduino-compatible Bare Bones Board and Boarduino boards may provide male header pins on the underside of the board to be plugged into solderless breadboards.There are many Arduino-compatible and Arduino-derived boards. Some are functionally equivalent to an Arduino and may be used interchangeably. Many are the basic Arduino with the addition of commonplace output drivers, often for use in school-level education to simplify the construction of buggies and small robots. Others are electrically equivalent but change the form factor, sometimes permitting the continued use of Shields, sometimes not. Some variants use completely different processors, with varying levels of compatibility.

DevelopmentThe core Arduino developer team is composed of Massimo Banzi, David Cuartielles, Tom Igoe, Gianluca Martino, David Mellis and Nicholas Zambetti. Massimo Banzi was interviewed on the March 21st, 2009 episode (Episode 61) of FLOSS Weekly on the TWiT.tv network, in which he discussed the history and goals of the Arduino project.[19] He also gave a talk at TEDGlobal 2012 Conference, where he outlined various uses of Arduino boards around the world. Arduino is open source hardware: the Arduino hardware reference designs are distributed under a Creative Commons Attribution Share-Alike 2.5 license and are available on the Arduino Web site. Layout and production files for some versions of the Arduino hardware are also available. The source code for the IDE is available and released under the GNU General Public License, version 2. Although the hardware and software designs are freely available under copyleft licenses, the developers have requested that the name "Arduino" be exclusive to the official product and not be used for derivative works without permission. The official policy document on the use of the Arduino name emphasizes that the project is open to incorporating work by others into the official product. Several Arduino-compatible products commercially released have avoided the "Arduino" name by using "-duino" name variants.

Pin Description of Microcontroller ATMEGA32:

vcc :- Digital Supply Voltage.

GND :- Ground.Port A (PA7..PA0) :- Port A serves as the analog inputs to the A/D Converter. Port A also serves as an 8-bit bi-directional I/O port, if the A/D Converter is not used. Port pins Port A also serves as an 8-bit bi-directional I/O port, if the A/D Converter is not used. Port pins metrical drive characteristics with both high sink and source capability. When pins PA0 to PA7 are used as inputs and are externally pulled low, they will source current if the internal pull-up.Port B (PB7..PB0) :- Port B is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port B output buffers have symmetrical drive characteristics with both high sink and source capability.Port C (PC7..PC0) :- Port C is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The C output buffers have symmetrical drive characteristics with both high sink and source capability.Port D (PD7..PD0) :- Port D is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The D output buffers have symmetrical drive characteristics with both high sink and source capability.RESET :- Reset Input. A low level on this pin for longer than the minimum pulse length will generate a reset, even if the clock is not running. The minimum pulse length is given in Shorter pulses are not guaranteed to generate a reset.XTAL1 :- Input to the inverting Oscillator amplifier and input to the internal clock operating circuit.XTAL2 :- Output from the inverting Oscillator amplifier.AV CC : AVCC is the supply voltage pin for Port A and the A/D Converter.AREF :- AREF is the analog reference pin for the A/D Converter.POWER SUPPLY: The ATmega32 is specified at a power supply voltage of 4.5V to 5.5V, 16MHz maximum frequency. The ATmega32L is specified at a power supply voltage of 2.7V to 5.5V, and a clock frequency of 8MHz. There is no derating of the frequency based on power supply voltage.Difference between ATmega32 and ATmega16:ATmega32 is very much similar to ATmega16 microcontroller with certain differences which are discussed below. ATmega32 is an 8-bit high performance microcontroller of Atmels MegaAVRfamily. Atmega32 is based on enhanced RISC (Reduced Instruction Set Computing) architecture with 131 powerful instructions. Most of the instructions execute in one machine cycle. Atmega32 can work on a maximum frequency of 16MHz.The differences between ATmega32 and ATmega16 can be summarized as follows:1. ATmega32 has 32 KB programmable flash memory, static RAM of 2 KB and EEPROM of 1 KB. The endurance cycle of flash memory and EEPROM is 10,000 and 100,000, respectively.ATmega32ATmega16

RAM2 KB1 KB

Flash32 KB16 KB

EEPROM1 KB512 bytes

2. The Bootloader area, the NRWW section starts at word 0x3800 in ATmega32 while in ATmega16 it starts at 0x1C00.3. ATmega32 has a different interrupt table, the table given below shows the difference. More details can be obtained from the respective datasheets.

Vector #ATmega32ATmega16

1ResetReset

2INT0INT0

3INT1INT1

4INT2Timer2 COMP

5Timer2 COMPTimer2 OVF

6Timer2 OVFTimer1 CAPT

7Timer1 CAPTTimer1 COMPA

8Timer1 COMPATimer1 COMPB

9Timer1 COMPBTimer1 OVF

10Timer1 OVFTimer0 OVF

11Timer0 COMPSPI, STC

12Timer0 OVFUSART, RXC

13SPI, STCUSART, UDRE

14USART, RXCUSART, TXC

15USART, UDREADC

16USART, TXCEE_RDY

17ADCANA_COMP

18EE_RDYTWI

19ANA_COMPINT2

20TWITimer0 COMP

21SPM_RDYSPM_RDY

4. In MCUCR register, the SM2 and SE bits are swapped, i.e., the SM2 bit is bit7 and SE bit is bit6 in MCUCR register in ATmega32.

CIRCUIT DIAGRAM:

PCB LAYOUT:

Fig.An actual size pcb,single side PCB for the ATmega32 development board

Components used:1.AVR:TheAVRis amodified Harvard architecture8-bitRISCsingle chipmicrocontrollerwhich was developed byAtmelin 1996. The AVR was one of the first microcontroller families to use on-chipflash memoryfor program storage, as opposed toone-time programmable ROM,EPROM, orEEPROMused by other microcontrollers at the time.The AVR is a modifiedHarvard architecturemachine where program and data are stored in separate physical memory systems that appear in different address spaces, but having the ability to read data items from program memory using special instructions.AVRs have been used in various automotive applications such as security, safety, powertrain and entertainment systems. Atmel has recently launched a new publication "Atmel Automotive Compilation" to help developers with automotive applications. Some current usages are in BMW, Daimler-Chrysler and TRW.Features:AVRs offer a wide range of features: Multifunction, bi-directional general-purpose I/O ports with configurable, built-inpull-up resistors Multiple internal oscillators, including RC oscillator without external parts Internal, self-programmable instructionflash memoryup to 256kB (384kB on XMega) In-system programmableusing serial/parallel low-voltage proprietary interfaces orJTAG Optional boot code section with independent lock bits for protection On-chip debugging (OCD) support through JTAG ordebugWIREon most devices The JTAG signals (TMS, TDI, TDO, and TCK) are multiplexed onGPIOs. These pins can be configured to function as JTAG or GPIO depending on the setting of a fuse bit, which can be programmed via ISP or HVSP. By default, AVRs with JTAG come with the JTAG interface enabled. debugWIREuses the /RESET pin as a bi-directional communication channel to access on-chip debug circuitry. It is present on devices with lower pin counts, as it only requires one pin. Internal dataEEPROMup to 4kB InternalSRAMup to 16kB (32kB on XMega) External 64kB little endian data space on certain models, including the Mega8515 and Mega162. The external data space is overlaid with the internal data space, such that the full 64kB address space does not appear on the external bus and accesses to e.g. address 010016will access internal RAM, not the external bus. In certain members of the XMega series, the external data space has been enhanced to support both SRAM and SDRAM. As well, the data addressing modes have been expanded to allow up to 16MB of data memory to be directly addressed. AVRs generally do not support executing code from external memory. SomeASSPsusing the AVR core do support external program memory. 8-bit and 16-bit timers PWMoutput (some devices have an enhanced PWM peripheral which includes a dead-time generator) Input capturethat record a time stamp triggered by a signal edge Analog comparator 10 or 12-bitA/D converters, with multiplex of up to 16 channels 12-bitD/A converters A variety of serial interfaces, including ICcompatible Two-Wire Interface (TWI) Synchronous/asynchronous serial peripherals (UART/USART) (used withRS-232,RS-485, and more) Serial Peripheral Interface Bus(SPI) Universal Serial Interface (USI) for two or three-wire synchronous data transfer Brownoutdetection Watchdog timer(WDT) Multiple power-saving sleep modes Lighting and motor control (PWM-specific) controller models CANcontroller support USBcontroller support Proper full-speed (12 Mbit/s) hardware & Hub controller with embedded AVR. Also freely available low-speed (1.5 Mbit/s) (HID)bitbangingsoftware emulations Ethernetcontroller support LCDcontroller support Low-voltage devices operating down to 1.8V (to 0.7V for parts with built-in DCDC upconverter) picoPower devices DMAcontrollers and "event system" peripheral communication2.Max232the MAX232 IC is used to convert the TTL/CMOS logic levels to RS232 logic levels during serial communication of microcontrollers with PC. The controller operates at TTL logic level (0-5V) whereas the serial communication in PC works on RS232 standards (-25 V to + 25V). This makes it difficult to establish a direct link between them to communicate with each other. The intermediate link is provided through MAX232. It is a dual driver/receiver that includes a capacitive voltage generator to supply RS232 voltage levels from a single 5V supply. Each receiver converts RS232 inputs to 5V TTL/CMOS levels. These receivers (R1 & R2) can accept 30V inputs. The drivers (T1 & T2), also called transmitters, convert the TTL/CMOS input level into RS232 level.The transmitters take input from controllers serial transmission pin and send the output to RS232s receiver. The receivers, on the other hand, take input from transmission pin of RS232 serial port and give serial output to microcontrollers receiver pin. MAX232 needs four external capacitors whose value ranges from 1F to 22F.

MicrocontrollerMAX232RS232

TxT1/2 InT1/2 OutRx

RxR1/2 OutR1/2 InTx

Pin Diagram:

Pin NoFunctionName

1Capacitor connection pinsCapacitor 1 +

2Capacitor 3 +

3Capacitor 1 -

4Capacitor 2 +

5Capacitor 2 -

6Capacitor 4 -

7Output pin; outputs the serially transmitted data at RS232 logic level; connected to receiver pin of PC serial portT2 Out

8Input pin; receives serially transmitted data at RS 232 logic level; connected to transmitter pin of PC serial portR2 In

9Output pin; outputs the serially transmitted data at TTL logic level; connected to receiver pin of controller.R2 Out

10Input pins; receive the serial data at TTL logic level; connected to serial transmitter pin of controller. T2 In

11T1 In

12Output pin; outputs the serially transmitted data at TTL logic level; connected to receiver pin of controller.R1 Out

13Input pin; receives serially transmitted data at RS 232 logic level; connected to transmitter pin of PC serial portR1 In

14Output pin; outputs the serially transmitted data at RS232 logic level; connected to receiver pin of PC serial portT1 Out

15Ground (0V)Ground

16Supply voltage; 5V (4.5V 5.5V)Vcc

3.AT24C02:It is an electrically erasable and programmable ROM. It has a 2Kbits of memory size arranged in 32 pages of 8 byte each. There are 256 (32 x 8) words each of one byte. The data is transferred and received serially through serial data (SDA) pin. The SCL is clock input and is used to synchronize EEPROM with microcontroller for various operations. When data is to be read or write, first a start condition is created followed by device address, byte address and the data itself. Finally a stop condition is provided. The start condition occurs when SDA and SCL get high to low simultaneously. The stop condition is when SDA remains low while SCL goes from high to low. The data is read or written between the start and stop conditions on every transition of SCL from high to low. For more details on different operations and addressing, refer interfacing 24C02 with 8051.A total of eight EEPROMs can be connected through a bus. There are three address pins in AT24C02 for selecting a particular chip. The device can be addressed serially by the software. It makes use of an internal register of the EEPROM whose 4 MSB bits are 1010, the next three are the EEPROM address bits and the LSB signifies whether data is to be read or written. This last bit is 1 for write and 0 for read operation. For example, if in an EEPROM all address bits are grounded, then for write operation a hex value 0xA1 (1010 0001) will be sent. Here 000, in last bits, addresses the EEPROM and 1 in LSB indicates a write operation. Similarly for read operation the device address to be sent is 0xA0 (1010 0000). Next, the byte or page address is sent followed by the data byte. This data byte is to be written on or read by the microcontroller.

Pin Diagram:

Pin Description:

Pin NoFunctionName

1Address input pins; Provide addresses when more than one EEPROM is interfaced to a single microcontroller;Ground when only one EEPROM is usedAD0

2AD1

3AD2

4Ground (0V)Ground

5Bi-directional pin for serial data transferSerial Data

6Provides clock signalsSerial Clock

7Ground allows normal read/write functions; Vcc enables write protectionWrite protect

8Supply voltage; 5V (up to 5.5V)Vcc

4. Resistor:A resistor is a two terminal electronic component that produces a voltage across its terminal that is proportional to the electric I though it in accordance with Ohm s law V=IRResistors are elements of electrical network and the electronic ckts and used in most electronic equipment. They made from films as well as from resistance wire. Fig5.11 resistor 6..Diode:In electronic, a diode is a type of two terminal electronic components with a non linear current voltage characteristic. A semiconductor diode the most common type today, is a crystalline piece of semiconductor material connected to two terminals. A vacuum tube diode is a vacuum tube with two electrodes a plate and a cathode. Fig5.12 diode Fig 5.13 physical description7.Crystal oscillators:Oscillator provides a constant frequency output under varying conditions. The factors which affect the frequency stability are temperature, variations in the load and changes in the power supply. For very high stability a quartz crystal is used as the frequency determining device to produce another type s of oscillator circuit known generally as Crystal oscillators. Fig5.9 crystal Oscillator 8. LCD DISPLAY 16X2A liquid crystal display (LCD) is a thin, flat panel used for electronically displaying information such as text, images, and moving pictures. Its uses include monitors for computers, televisions, instrument panels, and other devices ranging from aircraft cockpit displays, to every-day consumer devices such as video players, gaming devices, clocks, watches, calculators, and telephones.

Interfacing 162 LCD with Atmega32 Atmel AVR Microcontroller using Atmel Studio is bit complex as there is nobuiltin libraries. To solve this difficulty we developed a LCD library which includes the commonly used features. Just include our header file and enjoy. You can download the header file from the bottom of this article.162 LCD can be interfaced with a microcontroller in 8 Bit or 4 Bit mode. These differs in how data and commands are send to LCD. In 8 Bit mode character data (as 8 bit ASCII) and LCD command aresentthrough the data lines D0 to D7. That is 8 bit data is send at a time and data strobe is given through E of the LCD.But 4 Bit mode uses only 4 data lines D4 to D7. In this 8 bit data is dividedintotwo parts and aresentsequentially through the data lines. The idea of 4 bit communication is introduced to save pins of microcontroller. 4 bit communication is bit slower than 8bit but this speed difference has no significance as LCDs are slow speed devices. Thus 4 bit mode data transfer is most commonly used.Here to interface LCD with Avr, an 8 bit data bus is required. In addition we need 2 bit control bus for write only mode or 3 bit control bus for Read plus write mode. Connect pin 1 of the LCD module to ground, pin 2 to +ve supply. Connect a Pot (2 to 5 K Ohm) across the supply and ground. Connect the middle pin of the pot to pin3 of LCD module. If you want to light up the back light, connect theLED pin to ground. Connect the+LED pin of the LCD to the +ve supply using a resistor. Figure below is the two circuit diagrams!

LCD Pin description:

Pin nonamefunction

1VssGround

2Vdd+ve supply

3VeeContrast

4RSRegister select

5R/WRead/Write

6EEnable

7D0Data bit 0

8D1Data bit 1

9D2Data bit 2

10D3Data bit 3

11D4Data bit 4

12D5Data bit 5

1314D6D7Data bit 6Data bit 7

Table 5.1 LCD pin Description

9.Electrolytic Capacitor:The Electrolytic Capacitors are formed from two metallic sheets,cylindrically wrapped,that are seprated by aa thin oxide layer.The very thin layer thickness and its relative static permittivity value,relatively high,allow to get huge capacitance values even if they can suffer a potential difference of a few ten volts only.One plate must be +ve and other is ve polarity. Fig5.14 Electrolytic capacitors

10. Ceramic capacitor:These are constituted from a sandwich of conductor sheets altered with ceramic material. In these capacitors the dielectric material is ceramic agglomerate whose static permittivity value can be changed from 10 to 10,000 by dedicated compositions. The ceramic capacitors, with low relative permittivity value, have a stable capacitive value and very low losses, so they are preferred in the floating and high precision circuits.

11. Heat sink:A heat sink is a term for a component or assembly that transfers heat generated within a solid material to a fluid medium, such as air or a liquid. Examples of heat sink are the heat exchangers used in refrigeration, the air conditioning systems and also radiator in a car. Heat sink also helps to cool electronic and optoelectronic devices, such as higher power lasers and light emitting diodes (LED).A heat sink is physically designed to increase the surface area with the cooling fluid surrounding it, such as a air. The factors which affect the thermal resistance are air velocity, choice of material, fin design etc. One engineering application of heat sink is in the thermal management of electronics, often computer central processing unit (CPU) or graphic processors. For these, heat sink attachment methods and thermal interface materials also influence the eventual junction or dir temperature of the processor. Thermal grease is added to the base of the heat sink to help its thermal performance.

Fig 5.16 Heat sink12. Power supply:Power supplies are designed to convert high voltage AC mains to a suitable low voltage supply for electronic circuits and other devices. A power supply can be broken down into a series of blocks, each of which performs a particular function. For example a 5V regulated supply:

fig 5.17block diagram of regulated power supply

Each of the block has its own function as described below:Transformer steps down high voltage AC mains to low voltage AC.Rectifier converts AC to DC, but the DC output is varying. Smoothing smoothes the DC from varying greatly to a small ripple.Regulator eliminates ripple by setting DC output to a fixed voltage.

13. SIP:It is a combination of the resistance which is used at a port to connect the other components.SIP is a simple tool kit that service providers can use to build converged voice and multimedia services.

Fig

14. Voltage regulator:A voltage regulator is an electrical regulator designed to automatically maintain a constant voltage level. A voltage regulator may be simple feed forward design or may include ve feedback control loops. It may use an electromechanical mechanism, or electronic components. Depending on the design, it may be used to regulate one or more AC or DC voltages. Electronic voltage regulators are found in devices such as computer power supplies where they stabilize the DC voltages used by the processor and the other elements. In automobile alternators and central power station generators plants, voltage regulators control the output of the plant. The 7812 voltage regulators are used in the project.

15. Connectors:An electrical connector is an electro-mechanical device joining circuits as an interface using a mechanical assembly .The connection may be temporary, as for portable equipment, require a tool for assembly and removal, or serve as a permanent electrical joint between two wires. There are hundreds of types of electrical connectors. Connectors may join two lengths of flexible copper wire; connect a wire to interface to an electrical terminal.

16.TransformerMost power supplies use a step-down transformer to reduce the dangerously high mains voltage (230V in UK) to a safer low voltage. The input coil is called the primary and the output coil is called the secondary. There is no electrical connection between the two coils, instead they are linked by an alternating magnetic field created in the soft-iron core of the transformer. The two lines in the middle of the circuit symbol represent the core.Transformers waste very little power so the power out is (almost) equal to the power in. Note that as voltage is stepped down current is stepped up. The ratio of the number of turns on each coil, called the turn ratio, determines the ratio of the voltages. A step-down transformer has a large number of turns on its primary (input) coil which is connected to the high voltage mains supply, and a small number of turns on its secondary (output) coil to give a low output voltage.

Turns ratio = Vp = Np Vs Ns

And Power Out = Power In Vs Is = Vp Ip Where Vp = primary (input) voltage Np = number of turns on primary coil Ip = primary (input) current Ns = number of turns on secondary coil Is = secondary (output) current Vs = secondary (output) voltage

17.BRIDGE RECTIFIERA bridge rectifier can be made using four individual diodes, but it is also available in special packages containing the four diodes required. It is called a full-wave rectifier because it uses all AC wave (both positive and negative sections). 1.4V is used up in the bridge rectifier because each diode uses 0.7V when conducting and there are always two diodes conducting, as shown in the diagram below. Bridge rectifiers are rated by the maximum current they can pass and the maximum reverse voltage they can withstand (this must be at least three times the supply RMS voltage so the rectifier can withstand the peak voltages). In this alternate pairs of diodes conduct, changing over the connections so the alternating directions of AC are converted to the one direction of DC.

OUTPUT Full-wave Varying DC

SMOOTHINGSmoothing is performed by a large value electrolytic capacitor connected across the DC supply to act as a reservoir, supplying current to the output when the varying DC voltage from the rectifier is falling. The diagram shows the unsmoothed varying DC (dotted line) and the smoothed DC (solid line). The capacitor charges quickly near the peak of the varying DC, and then discharges as it supplies current to the output.

Note that smoothing significantly increases the average DC voltage to almost the peak value (1.4 RMS value). For example 6V RMS AC is rectified to full wave DC of about 4.6V RMS (1.4V is lost in the bridge rectifier), with smoothing this increases to almost the peak value giving 1.44.6=6.4V smooth DC. Smoothing is not perfect due to the capacitor voltage falling a little as it discharges, giving a small ripple voltage. For many circuits a ripple which is 10% of the supply voltage is satisfactory and the equation below gives the required value for the smoothing capacitor. A larger capacitor will give fewer ripples. The capacitor value must be doubled when smoothing half-wave DC. Smoothing capacitor for 10% ripple, C = 5 Io Vs f

Where

C = smoothing capacitance in farads (F)Io = output current from the supply in amps (A)Vs = supply voltage in volts (V), this is the peak value of the unsmoothed DCf = frequency of the AC supply in hertz (Hz), 50Hz

REGULATOR Voltage regulator ICs are available with fixed (typically 5, 12 and 15V) or variable output voltages. They are also rated by the maximum current they can pass. Negative voltage regulators are available, mainly for use in dual supplies. Most regulators include some automatic protection from excessive current (overload protection') and overheating (thermal protection'). Many of the fixed voltage regulator ICs has 3 leads and look like power transistors, such as the 7805 +5V 1A regulator shown on the right. They include a hole for attaching a heat sink if necessary. Working of Power SupplyTransformer

The low voltage AC output is suitable for lamps, heaters and special AC motors. It is not suitable for electronic circuits unless they include a rectifier and a smoothing capacitor.

Transformer + Rectifier

The varying DC output is suitable for lamps, heaters and standard motors. It is not suitable for electronic circuits unless they include a smoothing capacitor. Transformer + Rectifier + Smoothing

The smooth DC output has a small ripple. It is suitable for most electronic circuits. Transformer + Rectifier + Smoothing + Regulator

The regulated DC output is very smooth with no ripple. It is suitable for all electronic circuits.

5.4.3 Dual-In-Line Package

Fig5.6 Dual-in-line package

AdvantagesEliminates need for dual suppliesFour internally compensated op amps in a single packageAllows directly sensing near GND and Vout also goes to GNDCompatible with all forms of logicPower drain suitable for battery operation

2) 1) Interfacing LCD with Atmega32 (in 8 bit mode)-Circuit Diagram