;******************************************************************************* ; 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 Code Composer Essentials Version: 4.2.0 ;******************************************************************************* cdecls C,LIST, "msp430g2221.h" ; -.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 SetupUSI bis.b bis.b bis.b mov.b bic.b mov.b #LFXT1S_2,&BCSCTL1 ; ACLK = VL0 #USIMST,&USICTL0 ; SPI master #USIIE,&USICTL1 ; Counter interrupt, flag remains #USIDIV_7+USISSEL_1,&USICKCTL ; /128 ACLK #USISWRST,&USICTL0 ; Enable USI #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