The USI ; conunter ISR toggles P1.0 using software.. USICNT must be reloaded after each interrupt which also clears ; interrupt flag.. Dang ; Texas Instruments Inc.
Trang 1; MSP430G2x21/G2x31 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
;
; MSP430G2x21/G2x31
;
-; /|\|
XIN|-; | | |
; |RST
XOUT|-; | |
; | P1.0| >LED
;
; D Dang
; Texas Instruments Inc
; October 2010
; Built with IAR Embedded Workbench Version: 5.10
;*******************************************************************************
#include "msp430g2221.h"
ORG 0F800h ; Program Reset
; -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 Used MSP430G2xx1
ORG 0FFFEh ; MSP430 RESET Vector
DW RESET ;
ORG 0FFE8h ; USICNT
DW USI_ISR ;
END