Tone Generation using LPC2148....

AIM: Tone generation with Different delay.

THEORY:

Tone generation using digital I/O is simply creating a square wave of appropriate frequency. For this we can use the previous program of LED flashing as the base program. When we flash an LED, we use large delay for LED flashing to be visible. However, the tone frequencies are typically large. So the only modification required is to create separate delay routines with various delay values, typically in the range of 100uSec to 50mSec.
Also to create multiple tone effect, one tone should last for the required time. The tone frequency is decided by the delay used, and the tone duration is decided by the number of times the loop is executed. In the program given, we create three tones with different frequencies and durations.

PROCEDURE:

For creating project, we need to take following steps.

1) Create new project

2) Algorithm

3) Simulation of Algorithm

These three steps are involved in procedure.

1) Create new project

1.   Select a new project and give particular name to that project. e.g  Tone_gene

2.   Select chip NXP (founded by Philips) LPC2148.

3.   For assembly language don’t add startup file.

4.   Select a new editor file, write logic in that file and save it by using .c extension in embedded c language.

2) Algorithm

Algorithm consists of following steps.

Tone Generation:

1.   Select pin function

2.   Set the direction of the port

3.   Make particular pin high by using IOSET call delay.

4.   Clear pins by using IOCLR call delay.

3) Simulation of Algorithms

It consists of following steps.

1.   After writing program just build it.

2.   If there are any errors, they will be due to some mistake in typing the program. To locate the error, double click on the first error. Check for the error and remove it. Repeat this till all errors are gone.

3.   Now it’s time to debug. Click on the debug tab and debug program and observe contents of the variables in embedded c programming.

OBSERVATIONS:

1.   Observe pin P0.4 in proteus.

2.   Listen tone generated at P0.4.

  

Tone generation

In Embedded c:

#include <LPC214X.H>

void delay1(void);

void delay2(void);

int main(void)

{

int i;

delay1();

// select the pin function as GPIO

 PINSEL0 = 00;

// Set the port direction (P0.4-P0.7 port pins output)

IODIR0 = 0x000000F0;

     while(1)

    {

        for( i =0; i<500; i++)

        {

            IOCLR0 = 0x00000010;

            delay1();                      

            IOSET0 = 0x00000010;

            delay1();

        }

      for( i =0; i<500; i++)

        {

            IOCLR0 = 0x00000010;

            delay2();                      

            IOSET0 = 0x00000010;

            delay2();

        }

    for( i =0; i<100; i++)

        {

            IOCLR0 = 0x00000010;

            delay2(); delay2();                     

            IOSET0 = 0x00000010;

            delay2(); delay2();

        }

    }  

}

void delay1(void)

{

    unsigned int delay,s;

    for(s=200;s>0;s--)

    {

        for(delay = 10; delay > 0; --delay)

        {;}

    }

}

void delay2(void)

{

    unsigned int delay,s;

    for(s=400;s>0;s--)

    {

        for(delay = 10; delay > 0; --delay)

        {;}

    }

}

Proteus design:

  

1^st frequency

2^nd Frequency

3^rd Frequency