1) PIC microcontrollers

PIC 16F73 features

Pin diagram of PIC16F73

Pin description of PIC16F73

Core Architecture

2) Programming of PIC

Compiler Used-mikroC

Features

Projects

Functionality

3) Programming and Interfacing

Advantages of C over Assembly language programming

Project no. 1- LED interfacing and its blinking(port pro-

gramming)

Project no. 2- seven segment interfacing and display

Project no. 3- Interfacing and control of stepper motor with

PIC 16F73

Project no. 4-LCD interfacing and display with PIC 16F73

Project no. 5-Builtin ADC of PIC16F73(Temperature Mon-

itoring)

Project no. 6-To study switching action of PIC pins.

Project no. 7-Interfacing of keyboard matrix

Project no. 8-Serial communication [b/w PC & Microcon-

troller]

PIC

MICROCONTROLLER

PIC 16 SERIES-PIC16F73

PIC is a family of Harvard architecture microcontrollers made by Microchip

Technology, derived from the PIC1640 originally developed by General Instrument's

Microelectronics Division. The name PIC initially referred to "Peripheral Interface

Controller".

It is available in different configurations viz 8bit,16 bit,32 bit with instructions set as

given below :

Under 8 bit comes-PIC10 xxxx, PIC12 xxxx, PIC16 xxxx, PIC18 xxxx.(12 bit

instruction set)

Under 16 bit comes-PIC24H,DSPIC30,DSPIC33. (14 bit instruction set)

Under 32 bit comes-PIC32xxxx. (16 bit instruction set)

PICs are popular with developers and hobbyists alike due to their low cost, wide

availability, large user base, extensive collection of application notes, availability of

low cost or free development tools, and serial programming (and re-programming

with flash memory) capability.

Special Microcontroller Features:

• High performance RISC CPU.

• Only 35 single word instructions to learn.

• All single cycle instructions except for program branches which are two-cycle.

• Operating speed: DC - 20 MHz clock input DC - 200 ns instruction cycle.

• Up to 8K x 14 words of FLASH Program Memory, Up to 368 x 8 bytes of Data

Memory (RAM).

• Interrupt capability (up to 12 sources).

• Eight level deep hardware stack.

• Direct, Indirect and Relative Addressing modes.

• Processor read access to program memory.

• Power-on Reset (POR).

• Power-up Timer (PWRT) and Oscillator Start-up Timer (OST).

• Watchdog Timer (WDT) with its own on-chip RC oscillator for reliable operation.

• Programmable code protection

• Power saving SLEEP mode

• Selectable oscillator options

• In-Circuit Serial Programming (ICSP) via two pins.

Peripheral Features:

• Timer0: 8-bit timer/counter with 8-bit prescaler.

• Timer1: 16-bit timer/counter with prescaler, can be incremented during SLEEP via

external crystal/clock.

• Timer2: 8-bit timer/counter with 8-bit period register, prescaler and postscaler.

• Two Capture, Compare, PWM modules

- Capture is 16-bit, max. resolution is 12.5 ns

- Compare is 16-bit, max. resolution is 200 ns

- PWM max. resolution is 10-bit.

• 8-bit, up to 8-channel Analog-to-Digital converter.

• Synchronous Serial Port (SSP) with SPI (Master mode) and I2C(Slave).

• Universal Synchronous Asynchronous Receiver Transmitter (USART/SCI).

• Parallel Slave Port (PSP), 8-bits wide with external RD, WR and CS controls

(40/44-pin only).

• Brown-out detection circuitry for Brown-out Reset (BOR).

CMOS Technology:

• Low power, high speed CMOS FLASH technology.

• Fully static design.

• Wide operating voltage range: 2.0V to 5.5V.

• High Sink/Source Current: 25 Ma.

• Industrial temperature range.

• Low power consumption:

- < 2 mA typical @ 5V, 4 MHz

PIN DIAGRAM

PIN DESCRIPTION

MCLR-(pin 1)

PIC16F7X devices have a noise filter in the MCLR Reset path. The filter will detect

and ignore small pulses. It should be noted that a WDT Reset does not drive MCLR

pin low. The behavior of the ESD protection on the MCLR pin has been altered from

previous devices of this family. Voltages applied to the pin that exceed its

specification can result in both MCLR Resets and excessive current beyond the

device specification during the ESD event. For this reason, Microchip recommends

that the MCLR pin no longer be tied directly to VDD.

RESET

The PIC16F7X differentiates between various kinds of RESET:

Power-on Reset (POR) MCLR Reset during normal operation MCLR Reset during SLEEP WDT Reset (during normal operation) WDT Wake-up (during SLEEP) Brown-out Reset (BOR)Some registers are not affected in any RESET condion. Their status is unknown on

POR and unchanged n any other RESET. Most other registers are reset to a RESET

state” on Power-on Reset (POR), on the MCLR and WDT Reset, on MCLR Reset

during LEEP, and Brown-out Reset (BOR). They are not affected by a WDT Wake-

up, which is viewed as the resumption of normal operation. The TO and PD bits are

set or cleared differently in different RESET situations, as indicated

PORTA –(pin 2 to 7)and the TRISA Register-

PORTA is a 6-bit wide, bi-directional port. The corresponding data direction register

is TRISA. Setting a TRISA bit (= ‘1’) will make the corresponding PORTA pin an

input (i.e., put the corresponding output driver in a Hi-Impedance mode). Clearing a

TRISA bit (= ‘0’) will make the corresponding PORTA pin an output (i.e., put the

contents of the output latch on the selected pin).

Reading the PORTA register reads the status of the pins, whereas writing to it will

write to the port latch. All write operations are read-modify-write operations.

Therefore, a write to a port implies that the port pins are read, the value is modified

and then written to the port data latch.

GND –(pin 8)

Provide Ground to it.

OSC1/CLKIN-(pin 9)

Oscillator crystal input/external clock source input

OSC2/CLKOUT-(pin 10)

Oscillator crystal output. Connects to crystal or resonator in CrystalOscillator mode. In RC mode, the OSC2 pin outputs CLKOUTwhich has 1/4 the frequency of OSC1, and denotes the instructioncycle rate.

OSCILLATOR TYPES

The PIC16F7X can be operated in four different oscillator modes:

LP Low Power Crystal XT Crystal/Resonator HS High Speed Crystal/Resonator RC Resistor/Capacitor

PORTC and the TRISC Register(pin 11 to 18)

PORTC is an 8-bit wide, bi-directional port. The corresponding data direction

register is TRISC. Setting a TRISC bit (= ‘1’) will make the corresponding PORTC

pin an input (i.e., put the corresponding output driver in a Hi-Impedance mode).

Clearing a TRISC bit (= ‘0’) will

make the corresponding PORTC pin an output (i.e., put the contents of the output

latch on the selected pin).

PORTC is multiplexed with several peripheral functions PORTC pins have Schmitt

Trigger input buffers. When enabling peripheral functions, care should be taken in

defining TRIS bits for each PORTC pin.

Vss(pin 19)

Ground reference for logic and I/O pins

Vdd(pin 20)

Positive supply for logic and I/O pins

PORTB and the TRISB Register(pin 21 to 28)

PORTB is an 8-bit wide, bi-directional port. The corresponding data direction

register is TRISB. Setting a TRISB bit (= ‘1’) will make the corresponding PORTB

pin an input (i.e., put the corresponding output driver in a Hi-Impedance mode).

Clearing a TRISB bit (= ‘0’) will make the corresponding PORTB pin an output

(i.e., put the contents of the output latch on the selected pin).

Each of the PORTB pins has a weak internal pull-up. A single control bit can turn on

all the pull-ups. The weak pull-up is automatically turned off when the port pin is

configured as an output. The pull-ups are disabled on a Power-on Reset.

CORE ARCHITECTURE

Figure 2.1: Showing a typical microcontroller device and its different subunits

The PIC architecture is distinctively minimalist. It is characterized by the following

features:

Separate code and data spaces (Harvard architecture)

A small number of fixed length instructions

Most instructions are single cycle execution (4 clock cycles), with single delay

cycles upon branches and skips

A single accumulator (W), the use of which (as source operand) is implied (i.e. is

not encoded in the opcode)

All RAM locations function as registers as both source and/or destination of

math and other functions.

A hardware stack for storing return addresses

A fairly small amount of addressable data space (typically 256 bytes), ex-

tended through banking

Data space mapped CPU, port, and peripheral registers

The program counter is also mapped into the data space and writable (this is

used to implement indirect jumps).

Unlike most other CPUs, there is no distinction between memory space and register

space because the RAM serves the job of both memory and registers, and the RAM

is usually just referred to as the register file or simply as the registers

PROGRAMMING OF PIC

COMPILER USED -

mikroC

Introduction to mikroC

mikroC is a powerful, feature rich development tool for PICmicros. It is designed to provide the programmer with the easiest possible solution for developing applications for embedded systems, without compromising performance or control.

mikroC IDE

PIC and C fit together well: PIC is the most popular 8-bit chip in the world, used in a wide variety of applications, and C, prized for its efficiency, is the natural choice for developing embedded systems. mikroC provides a successful match featuring highly advanced IDE, ANSI compliant compiler, broad set of hardware libraries, comprehensive documentation, and plenty of ready-to-run examples.

Features

mikroC allows you to quickly develop and deploy complex applications:

Write your C source code using the built-in Code Editor (Code and Parameter Assistants, Syntax Highlighting, Auto Correct, Code Templates, and more…)

Use the included mikroC libraries to dramatically speed up the development: data acquisition, memory, displays, conversions, communications… Practi-cally all P12, P16, and P18 chips are supported.

Monitor your program structure, variables, and functions in the Code Ex-plorer.

Generate commented, human-readable assembly, and standard HEX compati-ble with all programmers.

Inspect program flow and debug executable logic with the integrated Debug-ger.

Get detailed reports and graphs: RAM and ROM map, code statistics, assem-bly listing, calling tree, and more…

We have provided plenty of examples for you to expand, develop, and use as building bricks in your projects. Copy them entirely if you deem fit – that’s why we included them with the compiler.

Projects

mikroC organizes applications into projects, consisting of a single project file (extension .ppc) and one or more source files (extension .c). You can compile source files only if they are part of a project.

The project file carries the following information:

project name and optional description, target device, device flags (config word), device clock,

New Project

The easiest way to create project is by means of New Project Wizard, drop-down menu Project › New Project. Just fill the dialog with desired values (project name and description, location, device, clock, config word) and mikroC will create the appropriate project file . Also, an empty source file named after the project will be created by default. mikroC does not require you to have source file named same as the project, it’s just a matter of convenience.

Edit Project

Later, you can change project settings from the drop-down menu Project › Edit Project. You can rename the project, modify its description, change chip, clock, config word, etc.

Also mikroC has some pre defined functions:

Commonly used is

1). Delay_ms(time)-it provides a delay of spcified time in ms.

Its internal code is similar to code given below:

Void delay_ms()

{int I;

While (i !=0)

{

i--;

}

Also PIC has a internal TRIS register which controls the flow of insructions from the corresponding port.

PROGRAMMING AND INTERFACING

Advantages of C over Assembly language programming:

Knowledge of the processor instruction set is not required.

Details like register allocation and addressing of memory and data is managed

by the compiler.

Programs get a formal structure and can be divided into separate functions.

Programming and program test time is drastically reduced, this increases effi-

ciency.

Keywords and operational functions can be used that come closer to how hu-

mans think.

The supplied and supported C libraries contain many standard routines such as

numeric conversions.

Reusable code: Existing program parts can be more easily included into new

programs, because of the comfortable modular program construction tech-

niques.

The C language based on the ANSI standard is very portable. Existing programs

can be quickly adapted to other processors as needed.

PROJECT NO-1

LED INTERFACING AND ITS BLINKING(PORT

PROGRAMMING)

the interfacing of LED is shown in the figure above.it is given Vcc through resistors

of 330E.

also a darlington pair IC is also used i.e.ULN 2803 which shift the dc level of volage

coming from port of pic microcontroller.

Now to glow the desired LED ,proper hexadecimal code for its binary is

programmed in pic.eg.to glow alternative LED’s the binary code will be10101010

and its corresponding hexadecimal code will be 0xAA.

So,0xAA is fed to controller with coding.

Also PIC has a internal TRIS register which controls the flow of insructions from the corresponding port i.ee PORT will behave as input(if =1) and as output(if=0).

CODING FOR BLINKING

void main()

{

PORTC = 0; // Initialize PORTC

TRISC = 0; // Configure PORTC as output

while(1)

{

PORTC = OxAA; // gives code 10101010 to PORTC

Delay_ms(1000); // one second delay

}}

Thus LED Blinking practical is done sucessfully.

PROJECT NO-2

SEVEN SEGMENT INTERFACING AND DISPLAY

A Seven segment display consists of seven LED’s arranged in pattern of digit like 8

We use a bcd to seven segment decoder which saves pin of microcontroller from

seven(one for each Led) to four.So we have to give bcd code for desired digit to be

displayed on it.

Now also we can display more then one seven segment display simultaneously.but it

will take a number of pins of controller.So we use two pins from controller to

control the display of seven segment one by one from same port such that it appears

to be displaying simultaneously.This is done by providing a very small delay such

that our eyes cant even detect the change over from one display to another.

CODING FOR DISPLAY

//seven segment display -common anode for 2 digit

void bcd(unsigned int x);

void delay(unsigned int k) ;

void main()

{

unsigned int i=0;

TRISB=0X00;

while(1)

{

i++;

bcd(i);

//delay_ms(20);

}}

void bcd(unsigned int x)

{

unsigned char z,y,a;

if(x<100)

{

for(a=0;a<100;a++)

{

y=(x/10)*6+x;

y=y>>4;

y=y|0xe0;

PORTB=y;

delay(250);

z=(x/10)*6+x;

z=z&0x0f;

z=z|0xd0;

PORTB=z;

delay(250);

}}}

void delay(unsigned int k)

{

while(k!=0)

{

k--;

}}

PROJECT NO-3

INTERFACING AND CONTROL OF STEPPER MOTOR WITH PIC 16F73

Stepper motor are those which rotates in steps.like all motors it is also based on

electromagnetic induction i.e. electric field produces a magnetic field whose

variation causes a torque which rotates the motor.

A stepper motor is a brushless, synchronous electric motor that can divide a full

rotation into a large number of steps. The motor's position can be controlled

precisely, without any feedback mechanism (see open loop control). Stepper motors

are similar to switched reluctance motors, which are very large stepping motors with

a reduced pole count, and generally are closed-loop commutated.

Fundamentals of Operation

Stepper motors operate much differently from normal DC motors, which rotate when voltage is applied to their terminals. Stepper motors, on the other hand, effectively have multiple "toothed" electromagnets (a.k.a. phases) arranged around a central gear-shaped piece of iron. The electromagnets are energized by an external control circuit, such as a microcontroller. To make the motor shaft turn, first one electromagnet is

given power, which makes the gear's teeth magnetically attracted to the electromagnet's teeth. When the gear's teeth are thus aligned to the first electromagnet, they are slightly offset from the next electromagnet. So when the next electromagnet is turned on and the first is turned off, the gear rotates slightly to align with the next one, and from there the process is repeated. Each of those slight rotations is called a "step." In that way, the motor can be turned a precise angle.

Now to run the motor we have to feed the binary code to turn on the current of that winding…

For pair 1st-00000011(binary)-0x03

For pair 2nd-00000110(binary)-0x06

For pair 3rd -000001100(binary)-0x0c

For pair 4th -00011000(binary)-0x09

CODE IS

#define l1 PORTB.F0

#define l2 PORTB.F1

#define l3 PORTB.F2

#define l4 PORTB.F3

void forward();

void backward();

void main()

{

PORTC=0XFF;

TRISB=0X00;

while(1)

{

forward();

delay_ms(2000);

backward();

delay_ms(2000);

}

}

void forward() //half stepping

{

unsigned char a;

for(a=0;a<10;a++)

{

l1=1; l2=0; l3=0; l4=0; delay_ms(100);

l1=0; l2=1; l3=0; l4=0; delay_ms(100);

l1=0; l2=0; l3=1; l4=0; delay_ms(100);

l1=0; l2=0; l3=0; l4=1;delay_ms(100);

}}

void backward()

{

unsigned char b;

for(b=0;b<10;b++)

{

l1=0; l2=0; l3=0; l4=1; delay_ms(100);

l1=0; l2=0; l3=1; l4=0; delay_ms(100);

l1=0; l2=1; l3=0; l4=0; delay_ms(100);

l1=1; l2=0; l3=0; l4=0; delay_ms(100);

}}

The above code will rotate the motor first in forward direction and then in reverse

direction.

Thus,stepper motor has been studied successfully.

PROJECT NO-4

LCD INTERFACING AND DISPLAY

LCD stands for Liquid Crystal Display.to run it via PIC 16F73,we need command

signals and vcc to drive it.now the signal that is required to display character is

produced by an IC which is already embedded on it.its name is HD44780.

PIN NO. NAME FUNCTION

1 Vss Ground

2 Vdd +ve supply

3 Vee contrast

4 RS Register select

5 R/W Read/Write

6 E Enable

7 D0 Data Bit 0

8 D1 Data Bit 1

9 D2 Data Bit 2

10 D3 Data Bit 3

11 D4 Data Bit 4

12 D5 Data Bit 5

13 D6 Data Bit 6

14 D7 Data Bit 7

Connections are shown as below

CODING

void main()

{

TRISB = 0; // PORTB is output

Lcd_Init(&PORTB); // Initialize LCD connected to PORTB

Lcd_Cmd(Lcd_CLEAR); // Clear display

Lcd_Cmd(Lcd_CURSOR_OFF); // Turn cursor off

Lcd_Out(1, 5,"HELLO"); // Print text to LCD, 1nd row, 5tH column

}

The above code will display HELLO on LCD.

The functions like Lcd_Init(),Lcd_cmd,Lcd_out are predefined functions in mikroC

which initialize,gives command and displays respectively.

Now also it is possible to scroll the characters on LCD. Its code is as follows:

Coding for scrolling

char *text = "AMAN" ;

char *text1 = "10748" ;

void main()

{

TRISB = 0; // PORTB is output

Lcd_Init(&PORTB); // Initialize LCD connected to PORTB

Lcd_Cmd(Lcd_CLEAR); // Clear display

Lcd_Cmd(Lcd_CURSOR_OFF); // Turn cursor off

Lcd_Out(1, 5,text); // Print text to LCD, 2nd row, 1st column

Lcd_Out(2, 5,text1);

while(1)

{

Lcd_Cmd(LCD_SHIFT_LEFT);

delay_ms(1000);

}

}

It will shift the character to the left with a delay of 1 sec between it.

Thus LCD display and scroll is studied successfully.

PROJECT NO-5

BUILT IN ADC OF PIC16F73(TEMPERATURE MONITORING)

PIC16F73 consists of 5 internal ADC .

AD are available in different configurations according to their bit channels.viz 8

bit(costs Rs.120),10bit(costs Rs.600),12 bit(costs Rs.1200-2000) ,14 bit(costs

Rs.2000-4000),16bit(costs Rs.4000-25000),24bit(costs >25000).

These are externally connected to microcontroller like AT89s51 which don’t have

inbuilt ADC.

Now as PIC 16xxx has got the feature of inbuilt ADC.so,there is no need to connect

externally.PIC16XXX is featured with 8 bit ADC.

So can convert an analog value to 8 bit binary or from 0 to 255 in decimal range.

The 8-bit analog-to-digital (A/D) converter module has five inputs for the PIC16F73/76 and eight for the PIC16F74/77.The A/D allows conversion of an analog input signal to a corresponding 8-bit digital number. The output of the sample and hold is the input into the converter, which generates the result via successive approximation. Theanalog reference voltage is software selectable to either the device’s positive supply voltage (VDD), or the voltage level on the RA3/AN3/VREF pin.The A/D converter has a unique feature of being able to operate while the device is in SLEEP mode. To operate in SLEEP, the A/D conversion clock must be derived from the A/D’s internal RC oscillator.The A/D module has three registers. These registersare:• A/D Result Register (ADRES)• A/D Control Register 0 (ADCON0)• A/D Control Register 1 (ADCON1)The ADCON0 register, shown in Register 11-1, controls the operation of the A/D module. The ADCON1 register, shown in Register 11-2, configures the functions of the port pins. The port pins can be configured as analog inputs (RA3 can also be a voltage reference), or as digital I/O.

ADC HARDWARE CONNECTION

From 4th pin we are gaetting Analog input.

ADCON0 REGISTER (ADDRESS 1Fh)

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 U-0 R/W-0ADCS1 ADCS0 CHS2 CHS1 CHS0 GO/DONE -------- ADONbit 7 bit 0

bit 7-6 ADCS1:ADCS0: A/D Conversion Clock Select bits00 = FOSC/201 = FOSC/810 = FOSC/3211 = FRC (clock derived from the internal A/D module RC oscillator)

bit 5-3 CHS2:CHS0: Analog Channel Select bits000 = channel 0, (RA0/AN0)001 = channel 1, (RA1/AN1)010 = channel 2, (RA2/AN2)011 = channel 3, (RA3/AN3)100 = channel 4, (RA5/AN4)101 = channel 5, (RE0/AN5)(1)110 = channel 6, (RE1/AN6)(1)111 = channel 7, (RE2/AN7)(1)bit 2 GO/DONE: A/D Conversion Status bitIf ADON = 1:1 = A/D conversion in progress (setting this bit starts the A/D conversion)0 = A/D conversion not in progress (This bit is automatically cleared by hardware whenthe A/D conversion is complete)bit 1 Unimplemented: Read as '0'bit 0 ADON: A/D On bit1 = A/D converter module is operating0 = A/D converter module is shutoff and consumes no operating current

ADCON1 REGISTER (ADDRESS 9Fh)

U-0 U-0 U-0 U-0 U-0 R/W-0 R/W-0 R/W-0— — — — — PCFG2 PCFG1 PCFG0

bit 7-3 Unimplemented: Read as '0'bit 2-0 PCFG2:PCFG0: A/D Port Configuration Control bits.

PCFG2:PCFG0 RA0 RA1 RA2 RA5 RA3 RE0(1) RE1(1) RE2(1) VREF 000 A A A A A A A A VDD 001 A A A A VREF A A A RA3 010 A A A A A D D D VDD 011 A A A A VREF D D D RA3 100 A A D D A D D D VDD 101 A A D D VREF D D D RA3 11x D D D D D D D D VDD

A = Analog inputD = Digital I/O

So,ADC will be provided analog input from different channels and correspondingly

these registers are set.

Now,coding to display voltage through temperature sensor

void ascii(unsigned int digit);

unsigned char table[]={'0','1','2','3','4','5','6','7','8','9'};

void main()

{

unsigned int e,f;

Lcd_Init(&PORTB);

Lcd_Cmd(Lcd_Clear);

Lcd_Cmd(LCD_CURSOR_OFF);

Lcd_Out(1, 1, "sensor temp=");

ADCON0 = 0x45; // Configure analog inputs and Vref

ADCON1 = 0x01;

TRISA = 0xFF; // PORTA is input

TRISB=0;

while(1)

{

e = Adc_Read(1); // first sensor

ascii(e);

delay_ms(1000) ;

f= Adc_Read(2); // second sensor

ascii(f) ;

}

}

void ascii(unsigned int digit)

{

unsigned char temp;

if(digit<100) //DECIMAL OR BINARY TO ASCII

{

temp=digit/10;

Lcd_Chr(1, 1, table[temp] );

temp=digit-temp*10;

Lcd_Chr(1, 2,table[temp] );

}}

PROJECT NO-6

TO STUDY SWITCHING ACTION OF PIC PINS.

As in AT89s51,the way of addressing pins is by p0.0,p0.1…..so on.

Similarly in PIC it is possible to address pins using

Syntax:

PORT( NAME).F(0 to 7)

Now pin can be put ON or OFF according to via resistor.

Internally,when pin is high its flip flop is sat.when external switch is closed ,it forces

no current or voltage to enter to pin and also lowers the pin from 1 to 0.

Thus when switch is pressed ,the pin becomes zero.so ,implementing this in

practical.

The swiches whose one end are connected to pins of nontroller are shown on next

page

The coding will be as follos:

#define s0 PORTC.F0

#define s1 PORTC.F1

#define s2 PORTC.F2

#define s3 PORTC.F3

#define s4 PORTC.F4

void main()

{

TRISB=0x00; \\ PORT B AS OUTPUT

TRISC=0xff; \\PORT C as input

PORTC=0xff; \\ ALL F/F’S TO SET

do

{

if(s0==0) \\1st switch is pressed

{

PORTB=0x80; \\1st LED glows

delay_ms(600);

}

if(s1==0) \\2nd switch is pressed

{

PORTB=0x40; \\2nd LED glows

delay_ms(600);

}

if(s2==0) \\3rd switch is pressed

{

PORTB=0x20; \\3rd LED glows

delay_ms(600);

}

if(s3==0) \\4th switch is pressed

{

PORTB=0x10; \\4th LED glows

delay_ms(600);

}

else

{

PORTB=0xff;

}}

while(1);

}

Thus switching action is studied.

PROJECT NO-7

INTERFACING OF KEYBOARD MATRIX

As in last practical, we use one switch per pin of controller. So, to use 8 pins for

8 switches.

While if it is desired to have more options for a pin, a matrix is formed in which row

and column are made such that each pin can control more than one switch or vice

versa.

h/w connection are

The coding for keyboard (4*4) matrix is as follows:

#define R1 PORTB.F0

#define R2 PORTB.F1

#define R3 PORTB.F2

#define R4 PORTB.F3

#define C1 PORTB.F4

#define C2 PORTB.F5

#define C3 PORTB.F6

#define C4 PORTB.F7

void main()

{

TRISB=0XFF;

TRISC=0X00;

PORTC=0X00;

PORTB=0XFF;

while(1)

{

if(R1==0 && C1==0)

{

PORTC=1;

}

if(R1==0 && C2==0)

{

PORTC=2;

}

if(R1==0 && C3==0)

{

PORTC=3;

}

if(R1==0 && C4==0)

{

PORTC=4;

}

if(R2==0 && C1==0)

{

PORTC=5;

}

if(R2==0 && C2==0)

{

PORTC=6;

}

if(R2==0 && C3==0)

{

PORTC=7;

}

if(R2==0 && C4==0)

{

PORTC=8;

}

if(R3==0 && C1==0)

{

PORTC=9;

}

if(R3==0 && C2==0)

{

PORTC=10;

}

if(R3==0 && C3==0)

{

PORTC=11;

}

if(R3==0 && C4==0)

{

PORTC=12;

}

if(R4==0 && C1==0)

{

PORTC=13;

}

if(R4==0 && C2==0)

{

PORTC=14;

}

if(R4==0 && C3==0)

{

PORTC=15;

}

if(R4==0 && C4==0)

{

PORTC=16;

}

}

}

Thus,the keyboard matrx practical is performed.

PROJECT NO-8

SERIAL COMMUNICATION(B/W PC AND MICROCONTROLLER)

To send data via single line through a bit stream is known as serial communication.

Reception is of type SIPO-Serial Input Parallel Output.

Transmission is of type PISO-Parallel Input Serial Output.

Clock used in serial communication is called BAUD RATE.

PIC has two buffers and it allows full duplex communication.to change settings we

have to re configure TXSTA register

The Universal Synchronous Asynchronous Receiver Transmitter (USART) module is one of the two serial I/O modules. (USART is also known as a Serial Communications Interface or SCI.) The USART can be configuredas a full duplex asynchronous system that can communicate with peripheral devices, such as CRT terminals and personal computers, or it can be configured as a half duplex synchronous system that can communicate with peripheral devices, such as A/D or D/A integratedcircuits, serial EEPROMs, etc.

The USART can be configured in the following modes:• Asynchronous (full duplex)• Synchronous - Master (half duplex)• Synchronous - Slave (half duplex)Bit SPEN (RCSTA<7>) and bits TRISC<7:6> have to be set in order to configure pins RC6/TX/CK and RC7/RX/DT as the Universal Synchronous Asynchronous Receiver Transmitter.

TXSTA: TRANSMIT STATUS AND CONTROL REGISTER (ADDRESS 98h

R/W-0 R/W-0 R/W-0 R/W-0 U-0 R/W-0 R-1 R/W-0CSRC TX9 TXEN SYNC — BRGH TRMT TX9D

bit 7 CSRC: Clock Source Select bit Asynchronous mode: Don’t care Synchronous mode: 1 = Master mode (Clock generated internally from BRG) 0 = Slave mode (Clock from external source)

bit 6 TX9: 9-bit Transmit Enable bit 1 = Selects 9-bit transmission 0 = Selects 8-bit transmissionbit 5 TXEN: Transmit Enable bit 1 = Transmit enabled 0 = Transmit disabledNote: SREN/CREN overrides TXEN in SYNC mode.

bit 4 SYNC: USART Mode Select bit 1 = Synchronous mode 0 = Asynchronous mode

bit 3 Unimplemented: Read as '0'

bit 2 BRGH: High Baud Rate Select bit Asynchronous mode: 1 = High speed 0 = Low speed Synchronous mode: Unused in this mode

bit 1 TRMT: Transmit Shift Register Status bit 1 = TSR empty 0 = TSR full

bit 0 TX9D: 9th bit of transmit data. Can be parity bit

now in mikroC UART terminal also work as shown as

Now coding

1).to transmit data..

void main()

{

usart_init(2400);

while(1)

{

usart_write('A');

usart_write('M');

usart_write('A');

usart_write('N');

delay_ms(600);

}

}

2).to transmit as well as read

unsigned int i;

void main()

{

usart_init(2400);

while(1)

{

if(usart_data_ready() )

{

i= usart_read();

usart_write('i');

}

usart_write('A');

usart_write('M');

usart_write('A');

usart_write('N');

delay_ms(600);

}

Thus serial communication has been studied successfully.

BIBLIOGRAPHY

Wikipedia MicroC Manuals www.talkingelectronics.com www.howstuffworks.com The Art of Electronics (Book)