IO Operations Revision as of 12:24, 17 March 2015 by Amruta (Talk | contribs) (diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)

Amruta (talk) 11:24, 17 March 2015 (IST)

---

Basics

lpc17xx header file

This is peripheral access header file for NXP LPC17xx device series. It contains all required register and peripheral definitions which one requires in order to access any peripheral.

If you take look at this header file, you will notice that all registers associated with a peripheral are clubbed together in a structure. So to access a register we need to use the respective structure

e.g. LPC_PINCON->PINSELx for PINSEL register,

     LPC_GPIO1->FIOSET for GPIO register, etc.

Code

In this code, we will demonstrate LED and Switch interfacing with the LPC1768. We will monitor the switch condition and will glow LED when switch is pressed.

#include "lpc17xx.h"   // NXP Library containing all port abd register definations
#include "stdutils.h"  // Explore Embedded library
 
#define LED		29	 //P1.29
#define SWITCH         28	 //P1.28
int main()
{
        SystemInit();
 
	LPC_PINCON->PINSEL3 = 0x00;			   // Configure Pin as GPIO
	util_BitSet(LPC_GPIO1->FIODIR,LED);	   	   // Set pin direction as output
	util_BitClear (LPC_GPIO1->FIODIR,SWITCH);	   // Set pin direction as input
 
	while(1)
	{		
		if (util_IsBitCleared (LPC_GPIO1->FIOPIN,SWITCH))	// check if switch is pressed
			util_BitSet (LPC_GPIO1->FIOSET,LED);	   // turn on LED	
		else
			util_BitSet (LPC_GPIO1->FIOCLR,LED);	// turn off LED	
	}
}
 
 
{{DISQUS}}