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2019-11-12 23:43:53 +02:00

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NASM
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; --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 - USICNT Used as a One-Shot Timer Function, DCO SMCLK
;
; Description: USI conunter is used as a one-shot timer. The USI
; conunter ISR toggles P1.0 using software. As coded ACLK is pre-divided by
; 128 and the USICNT loaded with 32, for a total divided of 4096 or
; 12-bits. USICNT must be reloaded after each interrupt which also clears
; interrupt flag.
; ACLK = VLO, MCLK = SMCLK = default DCO
;
; MSP430F20xx
; -----------------
; /|\| XIN|-
; | | |
; --|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 #WDTPW+WDTHOLD,&WDTCTL ; Stop watchdog timer
SetupP1 bis.b #01h,&P1DIR ; P1.1 output direction
SetupBC bis.b #LFXT1S_2,&BCSCTL1 ; ACLK = VL0
SetupUSI bis.b #USIMST,&USICTL0 ; SPI master
bis.b #USIIE,&USICTL1 ; Counter interrupt, flag remains
mov.b #USIDIV_7+USISSEL_1,&USICKCTL ; /128 ACLK
bic.b #USISWRST,&USICTL0 ; Enable USI
mov.b #08h,&USICNT ; init-load counter
;
Mainloop bis.w #LPM0+GIE,SR ; Enter LPM0, enable interrupts
jmp Mainloop ; Again
;
;-------------------------------------------------------------------------------
USI_ISR ;
;-------------------------------------------------------------------------------
xor.b #01h,&P1OUT ; Toggle P1.0
bis.b #01Fh,&USICNT ; re-load counter
reti ;
;
;------------------------------------------------------------------------------
; Interrupt Vectors
;------------------------------------------------------------------------------
.sect ".reset" ; MSP430 RESET Vector
.short RESET ;
.sect ".int04" ; USI Vector
.short USI_ISR ;
.end