ARM LPC2138/48 Mini Development Board – BUZZER Interfacing

LPC 2138/48 mini development board has an on-board buzzer connected to port pin P0.21 via jumper J10. To use the buzzer, it is necessary to short the jumper. If P0.21 is to be used for any other purpose, then the jumper should be left open.

Sample code to test the on-board buzzer using switch is given below. Here, pressing the switch SW1 generates an interrupt and toggles the status of buzzer.

Schematic

Note: To use buzzer, don’t forget to short jumper J10. Leaving it open frees P0.21 and can be used for any other desired purpose.

Sample Code

/**************************************************************************************
                                      HEADER FILES
***************************************************************************************/
#include<lpc21xx.h>

/**************************************************************************************
                                INTERRUPT SERVICE ROUTINE
***************************************************************************************/
void Ext_Interrupt(void)__irq 
{
 EXTINT      = 0X02;                               /* Clear interrupt flag            */
 IO0PIN      = (IO0PIN ^ 0X00200000) & 0x00200000; /* Toggle P0.21 on every interrupt */ 
 VICVectAddr = 0x00000000;                         /* Acknowledge Interrupt           */
}

/**************************************************************************************
* Function    : Init_Ext                                                                  *
*                                                                                         *
* Description : Function for initialising interrupt                                       *
*                                                                                         *
* Parameters  : None                                                                      *
***************************************************************************************/
void Init_Ext(void)
{
 PINSEL0     |= 0X20000000;                        /* Enable EXT1                     */
 EXTMODE      = 0X02;                              /* Edge sensitive                  */
 EXTPOLAR     = 0X02;                              /* Rising edge                     */
 VICVectAddr0 =(unsigned int)Ext_Interrupt;        /* Set Interrupt Vector in 0       */
 VICVectCntl0 = 0x0000002F;                        /* Use it for EXT1 Interrupt       */
 VICIntEnable = 0x00008000;                        /* Enable EXT1 INTERRUPT           */
}

/**************************************************************************************
                                     MAIN FUNCTION
***************************************************************************************/
int main(void) 
{
 IO0DIR = 0X00200000;                              /* P0.21 configured as output      */
 Init_Ext();
 while(1);
}

/**********************************  END OF PROGRAM  **********************************/

/**************************************************************************************

HEADER FILES

***************************************************************************************/

#include<lpc21xx.h>

/**************************************************************************************

INTERRUPT SERVICE ROUTINE

***************************************************************************************/

void Ext_Interrupt(void)__irq

{

EXTINT = 0X02; /* Clear interrupt flag */

IO0PIN = (IO0PIN ^ 0X00200000) & 0x00200000; /* Toggle P0.21 on every interrupt */

VICVectAddr = 0x00000000; /* Acknowledge Interrupt */

}

/**************************************************************************************

* Function : Init_Ext *

* *

* Description : Function for initialising interrupt *

* *

* Parameters : None *

***************************************************************************************/

void Init_Ext(void)

{

PINSEL0 |= 0X20000000; /* Enable EXT1 */

EXTMODE = 0X02; /* Edge sensitive */

EXTPOLAR = 0X02; /* Rising edge */

VICVectAddr0 =(unsigned int)Ext_Interrupt; /* Set Interrupt Vector in 0 */

VICVectCntl0 = 0x0000002F; /* Use it for EXT1 Interrupt */

VICIntEnable = 0x00008000; /* Enable EXT1 INTERRUPT */

}

/**************************************************************************************

MAIN FUNCTION

***************************************************************************************/

int main(void)

{

IO0DIR = 0X00200000; /* P0.21 configured as output */

Init_Ext();

while(1);

}

/********************************** END OF PROGRAM **********************************/

Topics related to ARM LPC2138/48 Mini Development Board

Resources

Softwares
- Keil uVision4 IDE
- Flash Utility Tool
Datasheets
- LPC 2148
- LPC 2138
- MCP 9700
- LM 7805
- LD 1117
- MAX 232

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