 C is general-purpose structured programming language or high level language.  It was developed by Dennis Ritchie in 1970s at Bell laboratories.  C supports a large no. of operators and a large no. of library function.  C is most popular language used for system programming,such as development of compilers, interpreters, assemblers, operating system like UNIX.

A typical C program has 3 sections: #include //Header file section #include void main( ) { int a,b; //Type declaration section //Instruction section }

#include main() { printf(“Hello World”); }

 A library function is a self-contained program that carries out some specific as well as defined tasks.  The function prototype or the reference is defined in the header files section so we have to include them in the beginning of program.  Example: #include, #define

 The statements used to change the control flow in a program are called the control statements or control structures in C.  Control statements: Logical if structure If-else structure Nested if-else Unconditional goto statement Switch structures

 The logical if structure checks a given logical condition and transfers the control accordingly. Syntax: If(condition) { Statement; } Example: if(x==3) { Y=2*x; }

#include int main() { int a=1; If(a==1) { printf(“true logic”); } If(a==0) { printf(“false logic”); } return 0; }

 The if-else structure is more useful than logical if structure. Syntax: if(expression) { S1;} else { S2; } Example: if(i==0) { s=s+1;} else { s=s-1;}

#include int main() { int a=1; If(a==1) { printf(“true logic”); } else { printf(“false logic”); } return 0; }

 C provides three loop structures to perform looping operations or iterations, in which a set of statements can be repeatedly executed as long as condition is satisfied. Loops are: while Do while For

 It is similar to the while-loop structure except that the condition is checked at the end of the loop. Syntax: do {S1; } while(condition); Example: do { i=i+1; } while(i <2);

#include int main() {int i=0; do{ printf(“value of i=%d”,i); i++; }while(i<10); return 0; }

In while-loop structure condition is checked at the starting of the loop. Syntax: while(condition) { s1; } Example: while(i>0) { j=j+1; }

#include int main() {int i=0; while (i<10){ printf(“value of i=%d”,i); i++; } return 0; }

 The expr1 is the statement assigning an initial value to a variable,expr2 is a logical expression and expr3 is a statement that is used to alter the value was assigned in the initial expression. Syntax: For(expr1;expr2;expr3) { statements; } Example: For(i=1;i<=5;i++) { j=j+1; }

#include int main() { int i; for(i=0;i<10;i++) { printf(“value of i=%d”,i); } return 0; }

 0;  1;  Binary to Decimal Conversion  Decimal to Binary Conversion

 0-9,  A,  B,  C,  D,  E,  F  Conversion  Decimal to Hexa decimal and vice versa  Binary to Hexa Decimal and vice versa

 0-7  Conversion

 ~ One’s Complement (unary operator)  >> Right Shift  << Left Shift  & Bitwise AND  | Bitwise OR  ^ Bitwise XOR (Exclusive OR)  Bitwise Compound Assignment Operators(eg. >=,|=,&=, and ^=)

#include int main() { unsigned char ch=32; unsigned char dh; dh=~ch; printf(“~ch=%d\n”,dh); printf(“~ch=%x\n”,dh); printf(“~ch=%X\n”,dh); return 0; }

Ch= ; Ch>>1 gives output ; Ch>>2 gives output ;

#include void showbits(unsigned char); int main() { unsigned char num=225,i,k; printf(“\n Decimal %d is same as hexa %x”,num,num); for(i=0;i<=5;i++) {k=num>>i; printf(“\n %d right shift %d gives %x”,num,I,k); //showbits(k);} return 0;}

 Same as right shift operator  <<

 Bitwise OR operator (|)  Bitwise AND operator (&)  Bitwise XOR operator(^)

 void showbits(unsigned char n)  { unsigned char i,k,andmask;  for(i=7;i>=0;i--)  { andmask=1<<i;  k=n & andmask;  If(k==0)  printf(“0”);  else printf(“1”);  }

ROBOT:  Robot is a machine that gathers information about its environment(senses) and uses that information to follow instructions to do work. MICROCONTROLLERS:  Microcontrollers is a single chip computer containing a processor core, memory and programmable input/output peripherals.

 DDRX: defines whether the port will act as i/p port or o/p port. 1 use for output 0 use for input Example: DDRA = 0b ; (binary) DDRA = 0xFF; (hexa decimal) DDRA = 1; (decimal) DDRA = 010; (octal)

 DDRX.Y: Define individual pin (pin Y of port X) acts as the i/p pin or the o/p pin Example: DDRA.3=1; pin 3 of port A is o/p port.

 PORTX: Use to assign value to PORTX. Example: PORTA=27 decimal value 27 is assigned to the portA.

 PORTX.Y: Use to assign value to individual pins(y) of any port (X). Example: PORTA.0=1 assign value 1 to the pin0 of the port A.

 PINX: Read 8-bit integer value from the port X. Example: X=PINA; Read the 8-bit integer value from the portA. 0<X<255  PINX.Y : Read 1-bit value (individual pin value) from PORTX. Example: X= PINA.2; ( value may be 0 or 1)

 PORTA is different from port A: PORTAPORTA PORTAPORTA DDRADDRA DDRADDRA PINAPINA PINAPINA uC External world Port A

P ROGRAMS : A program to o/p 33 (hex) on Port D. #include void main( ) { DDRD=0xFF; PORTD=0x33; }

P ROGRAMS : A program read pins 2 and 7 of Port A. #include void main( ) { unsigned int x,y; DDRA=0b ; x=PINA.2; y=PINA.7; }

+ - + VE GND Longer leg is +ve Terminal

PortAPortA PORTA=0b ; PORTA=0x02; Or For glowing LED PORTA.0=0 (GND) PORTA.1=1 (+V)

void main() { DDRB=0XFF; while(1) { PORTB=0XFF; delay_ms(100); PORTB=0X00; delay_ms(100); }