read from a Analog port

example of how to read a Analog signal from one of the port pins:

In this example I use the MSP430 Launchpad board, 74hc595 for displaying the Analog input, CDS photo cell.

//  MSP430G2231  
// Read from a analog signal from a port, and display it in bargraph format 
#include  <msp430x20x2.h>
#include <io.h>
#include <signal.h>
#include <stdlib.h>
#include <stdio.h>
char bar[9] = {0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x07, 0xff };
static void __inline__delay(register unsigned int n);
#define ANALOG_PIN      8
unsigned int analogRead(){
  ADC10CTL0 |= ADC10SC;
  while(ADC10CTL1 & ADC10BUSY);
  return ADC10MEM;
}
void analogPinSelect(unsigned int pin){
  if(pin < 8){
    ADC10CTL0 &= ~ENC;
    ADC10CTL1 = pin << 12;
    ADC10CTL0 = ADC10ON + ENC + ADC10SHT_0;
  }
}
void main( void )
{
int i, j, pin = 7;
char k;
WDTCTL = WDTPW + WDTHOLD; 
BCSCTL1 = CALBC1_1MHZ;
DCOCTL = CALDCO_1MHZ;
P1DIR |= 0x07; 
P1SEL = 0x00;
analogPinSelect( pin );
while( 1 )
  { 
ADC10CTL0 |= ADC10SC;             // Sampling and conversion start
k = ( analogRead() * 9) / 1024;

__inline__delay(0x8ff0); 

j = bar[k];
P1OUT &= ~BIT2;
for(i=0; i < 8; i++)
   {    
   P1OUT &= ~BIT1;
   if  (j & 0x01)
      {
      P1OUT |= BIT0;
      }else{
      P1OUT &= ~BIT0;
      }
P1OUT |= BIT1;
   j = j>>1;
   }
P1OUT |= BIT2;
}
}
// Delay Routine from mspgcc help file
static void __inline__delay(register unsigned int n)
{
  __asm__ __volatile__ (
  "1: \n"
  " dec %[n] \n"
  " jne 1b \n"
        : [n] "+r"(n));
}