;******************************************************************************
;   MSP-FET430P140 Demo - USART1, Ultra-Low Pwr UART 2400 Echo ISR, 32kHz ACLK
;
;   Description: Echo a received character, RX ISR used. Normal mode is LPM3,
;   USART0 RX interrupt triggers TX Echo.
;   ACLK = UCLK1 = LFXT1 = 32768Hz, MCLK = SMCLK = DCOCLK
;   Baud rate divider with 32768hz XTAL @2400 = 32768Hz/2400 = 13.65 (000Dh)
;   //* An external watch crystal on XIN XOUT is required for ACLK *//	
;
;                MSP430F149
;             -----------------
;         /|\|              XIN|-
;          | |                 | 32kHz
;          --|RST          XOUT|-
;            |                 |
;            |             P3.6|----------->
;            |                 | 2400 - 8N1
;            |             P3.7|<-----------
;
;   M. Buccini
;   Texas Instruments Inc.
;   Feb 2005
;   Built with IAR Embedded Workbench Version: 3.21A
;******************************************************************************
#include  <msp430x14x.h>
;------------------------------------------------------------------------------
            ORG     01100h                  ; Progam Start
;------------------------------------------------------------------------------
RESET       mov.w   #0A00h,SP               ; Initialize stackpointer
StopWDT     mov.w   #WDTPW+WDTHOLD,&WDTCTL  ; Stop WDT
SetupP3     bis.b   #0C0h,&P3SEL            ; P3.6,7 = USART1 option select
SetupUART1  bis.b   #UTXE1+URXE1,&ME2       ; Enable USART1 TXD/RXD
            bis.b   #CHAR,&UCTL1            ; 8-bit characters
            mov.b   #SSEL0,&UTCTL1          ; UCLK = ACLK
            mov.b   #00Dh,&UBR01            ; 32k/2400 - 13.65
            mov.b   #000h,&UBR11            ; 32k 2400
            mov.b   #06Bh,&UMCTL1           ; 32k 2400 modulation
            bic.b   #SWRST,&UCTL1           ; **Initialize USART state machine**
            bis.b   #URXIE1,&IE2            ; Enable USART1 RX interrupt
                                            ;
Mainloop    bis.b   #LPM3+GIE,SR            ; Enter LPM3, interrupts enabled
            nop                             ; Required only for debugger
                                            ;
;------------------------------------------------------------------------------
USART1RX_ISR;  Echo back RXed character, confirm TX buffer is ready first
;------------------------------------------------------------------------------
TX2         bit.b   #UTXIFG1,&IFG2          ; USART1 TX buffer ready?
            jz      TX2                     ; Jump is TX buffer not ready
            mov.b   &RXBUF1,&TXBUF1         ; TX -> RXed character
            reti                            ;
                                            ;
;------------------------------------------------------------------------------
;           Interrupt Vectors
;------------------------------------------------------------------------------
            ORG     0FFFEh                  ;
            DW      RESET                   ; POR, ext. Reset, Watchdog
            ORG     0FFE6h                  ;
            DW      USART1RX_ISR            ; USART1 receive
            END