Usar un 74HC165 con el MSP430 y 8 interruptores

Nota:
LD --> PIN_PL
CLK--> PIN_CP
Q7 --> PIN_Q


74hc165.h

/*
 * 74hc165.h
 */

#ifndef FILE_74HC165_H_
#define FILE_74HC165_H_

#include "msp430.h"
#define PISO_IN_PORT P1IN
#define PISO_OUT_PORT P1OUT
#define PIN_PL BIT5
#define PIN_CP BIT4
#define PIN_Q BIT3

#define PIN_CP_HIGH PISO_OUT_PORT |= PIN_CP
#define PIN_CP_LOW PISO_OUT_PORT &= ~PIN_CP
#define PIN_PL_HIGH PISO_OUT_PORT |= PIN_PL
#define PIN_PL_LOW PISO_OUT_PORT &= ~PIN_PL

void init74hc165 (void);
unsigned char read74hc165(void);

#endif /* FILE_74HC165_H_ */

74hc165.c

/*
 * 74hc165.c
 */

#include "74hc165.h"

void pulseClock (void){
 PIN_CP_HIGH;
 PIN_CP_LOW;
}

void init74hc165 (void){
 PIN_PL_HIGH;
 PIN_CP_HIGH;
}

unsigned char read74hc165(void){

 unsigned char i;
 unsigned char ret = 0;
 volatile unsigned char readed;

 PIN_CP_HIGH;
 PIN_PL_LOW;
 PIN_CP_LOW;
 PIN_PL_HIGH;

 for (i=0; i < 8; i++){

  readed = PISO_IN_PORT;

  if ((readed & PIN_Q) == PIN_Q){
   ret = ret + (128 >> (i));
  }

  pulseClock();
 }

 return ret;
}