This document provides C code solutions to interface four 7-segment displays on an ARM7 microcontroller and display counts from 0000 to 9999. The code defines arrays to store the digit values for the displays and uses conditions to extract the digits from the count value to display on the individual segments. Delay functions are used to control the timing of digit updates on the displays.

1. GPIO Seven Segment Display Interface
Program Statement: Interface four seven segment displays on GPIO’s of ARM7 LPC2148 and write a
C code to display count 0000 to 9999 on them with appropriate delay.
Solution:
# include<lpc214x.h>
void delay(void);
main()
{
char num[]={0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x67};
char t,j,h,i,k;
int m;
char num1[] = {0x00,0x00,0x00,0x00};
char num2[] = {0x70,0xb0,0xd0,0xe0};
int y;
IO0DIR = 0x00ffff00;
for(y=1;y<10000;y++)
{
if(y<10)
{
num1[3]=num[0];
num1[2]=num[0];
num1[1]=num[0];
num1[0]=num[y];
}
else if (y>= 10 && y <100)
{
num1[3]=num[0];
num1[2]=num[0];
num1[1]=num[y/10];
num1[0]=num[y-((y/10)*10)];
}
else if (y>= 100 && y <1000)
{
num1[3]=num[0];
num1[2]=num[y/100];
num1[1]=num[(y-((y/100)*100))/10];
num1[0]=num[y-((y/100)*100)-(((y-((y/100)*100))/10)*10)];
}
else
{
num1[3]=num[y/1000];
num1[2]=num[(y-((y/1000)*1000))/100];
LPC2148 Lecture Notes ENT505 Prof. Anish Goel Page 1

2. num1[1]=num[(y-((y/1000)*1000)-((y/100)*100))/10];
num1[0]=num[y-((y/1000)*1000)-((y/100)*100)-((y/10)*10)];
}
for(m=0;m<2;m++)
{
for(t=0;t<4;t++)
{
IO0SET = (num1[t] << 16) | (num2[t] << 8);
delay();
IO0CLR = (num1[t] << 16) | (num2[t] << 8);
delay();
}
}
}
}
void delay(void)
{
long int t;
for(t=0;t<30000;t++);
}
Serial Interface UART Block
Problem Statement: Write a program to send a string on serial port UART0 of LPC2148 continuously
at 9600 baud.
Solution Clue:
#include"LPC214x.h"
void Initialize(void);
/* Macro Definitions */
#define TEMT (1<<6);
#define LINE_FEED 0xA;
#define CARRIAGE_RET 0xD;
/************************* MAIN *************************/
int main()
{
int i;
char c[]="Philips LPC";
Initialize();
/* Print forever */
while(1)
{
i=0;
LPC2148 Lecture Notes ENT505 Prof. Anish Goel Page 2

3. /* Keep Transmitting until Null character('0') is reached */
while(c[i])
{
U0THR=c[i];
i++;
}
U0THR=LINE_FEED;
U0THR = CARRIAGE_RET;
/* Wait till U0THR and U0TSR are both empty */
while(!(U0LSR & (1<<6)))
{}
}
}
/*************** System Initialization ***************/
void Initialize()
{
/* Initialize Pin Select Block for Tx and Rx */
PINSEL0=0x5;
/* Enable FIFO's and reset them */
U0FCR=0x7;
/* Set DLAB and word length set to 8bits */
U0LCR=0x83;
/* Baud rate set to 9600 */
U0DLL=0x10;
U0DLM=0x0;
/* Clear DLAB */
U0LCR=0x3;
}
/*********************************************************/
16x2 LCD Program Hint
#include<lpc214x.h>
#include<STDIO.H>
#define line0 0x80
#define line1 0xc0
void delay(void);
void delay1(void);
void comdisp(char);
void comdata(char);
void display(char*,char);
main()
{
unsigned int x;
LPC2148 Lecture Notes ENT505 Prof. Anish Goel Page 3

4. IO0DIR=0xffffffff;
comdisp(0x38);
comdisp(0xf);
comdisp(0x6);
comdisp(0x87);
comdisp(0x1);
display("LPC 2148",line0);
display("ARM 7",line1+3);
}
void display(char *dat,char addr)
{
char count;
comdisp(addr);
for(count=0;dat[count];count++)
{
comdata(dat[count]);
}
}
void comdisp(char lcddata)
{
char word = 0xf9;
char word1 = 0xf1;
IO0SET = (lcddata<<8) | word;
delay1();
IO0SET = IO0SET && word1;
delay();
IO0CLR = 0x0000;
}
void comdata(char lcddata)
{
char word = 0xf3;
char word1 = 0xfb;
IO0SET = (lcddata<<8) | word;
delay1();
IO0CLR = ~(IO0SET && word1);
delay();
IO0CLR = 0xffff;
}
void delay(void)
{
int t;
for(t=0;t<1;t++);
}
void delay1(void)
{
int t;
for(t=0;t<1;t++);
}
LPC2148 Lecture Notes ENT505 Prof. Anish Goel Page 4