but.c

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/*
 * but.c
 *
 *  Date: 19/06/2014
 *  Author: Fernando Biazi Nascimento
 *  Copyright © 2014 Fernando Biazi Nascimento. All rights reserved.
 *
 *  License of use and copy on file license.txt
 *
 */

/*
 * ======== Standard MSP430 includes ========
 */
#include <msp430.h>

/*
 * ======== Includes ========
 */

#include "but.h"
#include "nwk.h"

/*
 * ======== Constants ========
 */

/*
 * ======== Macros ========
 */

#define BUT_SW0BIT BIT2

/*
 * ======== Types ========
 */

typedef enum but_state {
  BUT_S_IDLE, 
  BUT_S_PRESSED, 
  BUT_S_DEBOUNCE 
} but_state;

/*
 * ======== Global Variables ========
 */

/*
 * ======== Local Variables ========
 */

but_state but_currentState = BUT_S_IDLE;
UInt32 but_presses;
UInt8 but_pendingPress;

/*
 * ======== Local Functions ========
 */

/*
 * ================
 */

void but_init() {
  but_presses = 0;
  but_pendingPress = 0;
  but_currentState = BUT_S_IDLE;
  P1IE &= ~BUT_SW0BIT;
  P1REN |= BUT_SW0BIT;
  P1OUT |= BUT_SW0BIT;
  P1IES |= BUT_SW0BIT;
  P1IFG &= ~BUT_SW0BIT;
  P1IE |= BUT_SW0BIT;
}

UInt16 but_proccess() {

  if (but_presses & 0x80000000) {
    // count bits set on but_press
    //eliminate MSB, if there is far 1's, some loops are avoided.
    but_presses ^= 0x80000000;
    but_pendingPress = 1;
    while (but_presses != 0) {
      while (!(but_presses & 0xFF)) { // eliminate some loops if next 1 is far
        but_presses >>= 8;
      }
      while (!(but_presses & 0x0F)) { // eliminate some loops if next 1 is far
        but_presses >>= 4;
      }
      while (!(but_presses & 0x01)) {
        but_presses >>= 1;
      }
      but_pendingPress++;
      but_presses >>= 1;
    }
    if (but_pendingPress > 3) {
      // reset device
      WDTCTL = 0;
    } else if (but_pendingPress == 2) {
      nwk_setDeviceType(NWK_DEVTYPE_ROUTER);
    } else if (but_pendingPress == 1) {
      nwk_setDeviceType(NWK_DEVTYPE_ENDDEVICE);
    }
  }

  switch (but_currentState) {
  case BUT_S_IDLE:
    // delay prior presses
    but_presses <<= 1;
    // check again in 100ms
    return 100;
  case BUT_S_PRESSED:
    // delay prior presses
    but_presses <<= 1;
    // button pressed, register and only enable interrupt after 95ms to avoid bounce
    but_presses |= 0x01;
    but_currentState = BUT_S_DEBOUNCE;
    return 95;
  case BUT_S_DEBOUNCE:
    // this happens 95ms after previous call
    // clear flag, enable interrupt and back to idle
    P1IFG &= ~BUT_SW0BIT;
    P1IE |= BUT_SW0BIT;
    but_currentState = BUT_S_IDLE;
    return 5;
  default:
    but_currentState = BUT_S_IDLE;
    return 1;
  }
}

void but_clearPending() {
  but_pendingPress = 0;
}

UInt8 but_getPending() {
  return but_pendingPress;
}

void BUT_ISR() {
  if (but_currentState == BUT_S_IDLE) {
    but_currentState = BUT_S_PRESSED;
    P1IE &= ~BUT_SW0BIT; // disable interrupt to avoid bounce
  }
}