; --COPYRIGHT--,BSD_EX
;  Copyright (c) 2012, Texas Instruments Incorporated
;  All rights reserved.
; 
;  Redistribution and use in source and binary forms, with or without
;  modification, are permitted provided that the following conditions
;  are met:
; 
;  *  Redistributions of source code must retain the above copyright
;     notice, this list of conditions and the following disclaimer.
; 
;  *  Redistributions in binary form must reproduce the above copyright
;     notice, this list of conditions and the following disclaimer in the
;     documentation and/or other materials provided with the distribution.
; 
;  *  Neither the name of Texas Instruments Incorporated nor the names of
;     its contributors may be used to endorse or promote products derived
;     from this software without specific prior written permission.
; 
;  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
;  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
;  THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
;  PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
;  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
;  EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
;  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
;  OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
;  WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
;  OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
;  EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
; 
; ******************************************************************************
;  
;                        MSP430 CODE EXAMPLE DISCLAIMER
; 
;  MSP430 code examples are self-contained low-level programs that typically
;  demonstrate a single peripheral function or device feature in a highly
;  concise manner. For this the code may rely on the device's power-on default
;  register values and settings such as the clock configuration and care must
;  be taken when combining code from several examples to avoid potential side
;  effects. Also see www.ti.com/grace for a GUI- and www.ti.com/msp430ware
;  for an API functional library-approach to peripheral configuration.
; 
; --/COPYRIGHT--
;*******************************************************************************
;   MSP430F20xx Demo - LFXT1 Oscillator Fault Detection
;
;   Description: System runs normally in LPM3 with WDT timer clocked by
;   32kHz ACLK with a 1x4 second interrupt. P1.0 is normally pulsed every
;   second inside WDT interrupt. If an LFXT1 oscillator fault occurs,
;   NMI is requested forcing exit from LPM3. P1.0 is toggled rapidly by software
;   as long as LFXT1 oscillator fault is present. Assumed only LFXT1 as NMI
;   source - code does not check for other NMI sources.
;   ACLK = LFXT1 = 32768, MCLK = SMCLK = Default DCO
;
;   //*External watch crystal on XIN XOUT is required for ACLK*//	
;
;
;            MSP430F20xx
;          ---------------
;      /|\|            XIN|-
;       | |               | 32kHz
;       --|RST        XOUT|-
;         |               |
;         |           P1.0|-->LED;
;
;   P.Thanigai
;   Texas Instruments Inc.
;   May 2007
;   Built with Code Composer Essentials Version: 2.0
;*******************************************************************************
 .cdecls C,LIST,  "msp430.h"
;-------------------------------------------------------------------------------
            .def    RESET                   ; Export program entry-point to
                                            ; make it known to linker.
;------------------------------------------------------------------------------
            .text                           ; Program Start
;------------------------------------------------------------------------------
RESET       mov.w   #0280h,SP               ; Initialize stackpointer
StopWDT     mov.w   #WDT_ADLY_1000,&WDTCTL  ; WDT 1s interval timer
            bis.b   #WDTIE,&IE1             ; Enable WDT interrupt
SetupP1     mov.b   #0FFh,&P1DIR            ; All P1.x outputs
            clr.b   &P1OUT                  ; All P1.x reset
SetupP2     mov.b   #0FFh,&P2DIR            ; All P2.x outputs
            clr.b   &P2OUT                  ; All P2.x reset
; An immedate Osc Fault will occur next
            bis.b   #OFIE,&IE1              ; Enable osc fault interrupt
                                            ;						
Mainloop    xor.b   #001h,&P1OUT            ; Toggle P1.0
            bis.w   #LPM3+GIE,SR            ; Enter LPM3, enable interrupts
            jmp     Mainloop                ;
                                            ;
;-------------------------------------------------------------------------------
NMI_ISR;   Only osc fault enabled, R15 used temporarily and not saved
;          Assumed LFXT1 is only source for NMI interrupt
;-------------------------------------------------------------------------------
CheckOsc    bic.b   #OFIFG,&IFG1            ; Clear OSC fault flag
            xor.b   #001h,&P1OUT            ; Toggle P1.0
            mov.w   #03FFFh,R15             ; R15 = Delay
CheckOsc1   dec.w   R15                     ; Time for flag to set
            jnz     CheckOsc1               ;
            bit.b   #OFIFG,&IFG1            ; OSC fault flag set?
            jnz     CheckOsc                ; OSC Fault, clear flag again
            bis.b   #OFIE,&IE1              ; re-enable osc fault interrupt
            reti                            ; return from interrupt
                                            ;
;-------------------------------------------------------------------------------
WDT_ISR;    Exit LPM3 on reti
;-------------------------------------------------------------------------------
            bic.w   #LPM3,0(SP)             ;
            reti                            ;
                                            ;
;------------------------------------------------------------------------------
;           Interrupt Vectors
;------------------------------------------------------------------------------
            .sect   ".reset"                ; MSP430 RESET Vector
            .short  RESET                   ;
            .sect   ".int10"                ; WDT Vector
            .short  WDT_ISR                 ;
            .sect   ".int14"                ; NMI Vector
            .short  NMI_ISR            
            .end