Книга: Advanced PIC Microcontroller Projects in C

3.3 Programming Examples

3.3 Programming Examples

In this section, some simple programming examples are given to familiarize the reader with programming in C.

Write a program to set all eight port pins of PORTB to logic 1.

PORTB is configured as an output port, and then all port pins are set to logic 1 by sending hexadecimal number 0xFF:

void main() {
 TRISB = 0;    // Configure PORTB as output
 PORTB = 0xFF; // Set all port pins to logic a
}

Write a program to set the odd-numbered PORTB pins (bits 1, 3, 5, and 7) to logic 1.

Odd-numbered port pins can be set to logic 1 by sending the bit pattern 10101010 to the port. This bit pattern is the hexadecimal number 0xAA and the required program is:

void main() {
 TRISB = 0;    // Configure PORTB as output
 PORTB = 0xAA; // Turn on odd numbered port pins
}

Write a program to continuously count up in binary and send this data to PORTB. Thus PORTB requires the binary data:

00000000
00000001
00000010
00000011
........
........
11111110
11111111
00000000
........

A for loop can be used to create an endless loop, and inside this loop the value of a variable can be incremented and then sent to PORTB:

void main() {
 unsigned char Cnt = 0;
 for(;;) // Endless loop
 {
  PORTB = Cnt; // Send Cnt to PORTB
  Cnt++;       // Increment Cnt
 }
}

Write a program to set all bits of PORTB to logic 1 and then to logic 0, and to repeat this process ten times.

A for statement can be used to create a loop to repeat the required operation ten times:

void main() {
 unsigned char j;
 for(j = 0; j < 10; j++) // Repeat 10 times
 {
  PORTB = 0xFF; // Set PORTB pins to 1
  PORTB = 0;    // Clear PORTB pins
 }
}

The radius and height of a cylinder are 2.5cm and 10cm respectively. Write a program to calculate the volume of this cylinder.

The required program is:

void main() {
 float Radius = 2.5, Height = 10;
 float Volume;
 Volume = PI * Radius * Radius * Height;
}

Write a program to find the largest element of an integer array having ten elements.

At the beginning, variable m is set to the first element of the array. A loop is then formed and the largest element of the array is found:

void main() {
 unsigned char j;
 int m, A[10];
 m = A[0]; // First element of array
 for(j = 1; j < 10; j++) {
  if(A[j] > m) m = A[j];
 }
}

Write a program using a while statement to clear all ten elements of an integer array M.

As shown in the program that follows, NUM is defined as 10 and variable j is used as the loop counter:

#define NUM 10
void main() {
 int M[NUM];
 unsigned char j = 0;
 while (j < NUM) {
  M[j] = 0;
  j++;
 }
}

Write a program to convert the temperature from °C to °F starting from 0°C, in steps of 1°C up to and including 100°C, and store the results in an array called F.

Given the temperature in °C, the equivalent in °F is calculated using the formula:

F = (C – 32.0)/1.8

A for loop is used to calculate the temperature in °F and store in array F:

void main() {
 float F[100];
 unsigned char C;
 for(C = 0; C <= 100; C++) {
  F[C] = (C – 32.0) / 1.8;
 }
}

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