msp430x24x_uscia0_uart_05_9600.s43

来自「步进电机驱动程序msp430f247单片机」· S43 代码 · 共 68 行

;*******************************************************************************
;   MSP430x24x Demo - USCI_A0, Ultra-Low Pwr UART 9600 Echo ISR, 32kHz ACLK
;
;   Description: Echo a received character, RX ISR used. Normal mode is LPM3,
;   USCI_A0 RX interrupt triggers TX Echo.
;   ACLK = BRCLK = LFXT1 = 32768, MCLK = SMCLK = DCO ~1.045MHz
;   Baud rate divider with 32768Hz XTAL @9600 = 32768Hz/9600 = 3.41
;   //* An external watch crystal is required on XIN XOUT for ACLK *//
;
;                MSP430F249
;             -----------------
;         /|\|              XIN|-
;          | |                 | 32kHz
;          --|RST          XOUT|-
;            |                 |
;            |     P3.4/UCA0TXD|------------>
;            |                 | 9600 - 8N1
;            |     P3.5/UCA0RXD|<------------
;
;   B. Nisarga
;   Texas Instruments Inc.
;   September 2007
;   Built with IAR Embedded Workbench Version: 3.42A
;*******************************************************************************
#include  "msp430x24x.h"
;-------------------------------------------------------------------------------
            RSEG    CSTACK                  ; Define stack segment
;-------------------------------------------------------------------------------
            RSEG    CODE                    ; Assemble to Flash memory
;-------------------------------------------------------------------------------
RESET       mov.w   #SFE(CSTACK),SP         ; Initialize stackpointer
StopWDT     mov.w   #WDTPW+WDTHOLD,&WDTCTL  ; Stop WDT
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
SetupP3     bis.b   #030h,&P3SEL            ; P3.4,5 = USCI_A0 TXD/RXD
            mov.b   #0FFh,&P3DIR            ; All P3.x outputs
            clr.b   &P3OUT                  ; All P3.x reset
SetupP4     mov.b   #0FFh,&P4DIR            ; All P4.x outputs
            clr.b   &P4OUT                  ; All P4.x reset
SetupUSCI0  bis.b   #UCSSEL_1,&UCA0CTL1     ; CLK = ACLK
            mov.b   #03h,&UCA0BR0           ; 32kHz/9600 = 3.41
            mov.b   #00h,&UCA0BR1           ;
            mov.b   #UCBRS1+UCBRS0,&UCA0MCTL; Modulation UCBRSx = 3
            bic.b   #UCSWRST,&UCA0CTL1      ; **Initialize USCI state machine**
            bis.b   #UCA0RXIE,&IE2          ; Enable USCI_A0 RX interrupt
                                            ;
Mainloop    bis.b   #LPM3+GIE,SR            ; Enter LPM3, interrupts enabled
            nop                             ; Required for debugger
                                            ;
;-------------------------------------------------------------------------------
USCI0RX_ISR;  Echo back RXed character, confirm TX buffer is ready first
;-------------------------------------------------------------------------------
TX0         bit.b   #UCA0TXIFG,&IFG2        ; USCI_A0 TX buffer ready?
            jz      TX0                     ; Jump if TX buffer not ready
            mov.b   &UCA0RXBUF,&UCA0TXBUF   ; TX -> RXed character
            reti                            ;
                                            ;
;-------------------------------------------------------------------------------
            COMMON  INTVEC                  ; Interrupt Vectors
;-------------------------------------------------------------------------------
            ORG     USCIAB0RX_VECTOR        ; USCI0 Rx Vector
            DW      USCI0RX_ISR             ;
            ORG     RESET_VECTOR            ; RESET Vector
            DW      RESET                   ;
            END