;******************************************************************************
;   MSP-FET430P140 Demo - USART1, UART 19200 Echo ISR, XT2 HF XTAL SMCLK
;
;   Description: This program will echo a received character, RX interrupt
;   service used. XT2 oscillator used in this example.
;   ACLK = MCLK = SMCLK = UCLK1 = XT2 = 8MHz
;   Baud rate divider with 8Mhz XTAL @19200 = 8MHz/19200 = 416.66 ~ 417
;   //* An external 8MHz XTAL on X2IN X2OUT is required for ACLK *//	
;
;                MSP430F149
;             -----------------
;         /|\|             X2IN|-
;          | |                 | 8Mhz
;          --|RST         X2OUT|-
;            |                 |
;            |             P3.6|------------>
;            |                 | 19200 - 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
SetupBC     bic.b   #XT2OFF,&BCSCTL1        ; XT2on
SetupOsc    bic.b   #OFIFG,&IFG1            ; Clear OSC fault flag
            mov.w   #0FFh,R15               ; R15 = Delay
SetupOsc1   dec.w   R15                     ; Additional delay to ensure start
            jnz     SetupOsc1               ;
            bit.b   #OFIFG,&IFG1            ; OSC fault flag set?
            jnz     SetupOsc                ; OSC Fault, clear flag again
            bis.b   #SELM_2+SELS,BCSCTL2    ; MCLK = SMCLK = XT2 (safe)
SetupUART1  bis.b   #UTXE1+URXE1,&ME2       ; Enable USART1 TXD/RXD
            bis.b   #CHAR,&UCTL1            ; 8-bit characters
            mov.b   #SSEL1,&UTCTL1          ; UCLK = SMCLK
            mov.b   #0A0h,&UBR01            ; 8Mhz/19200 ~ 417
            mov.b   #001h,&UBR11            ;
            mov.b   #000h,&UMCTL1           ; no modulation
            bic.b   #SWRST,&UCTL1           ; **Initialize USART state machine**
            bis.b   #URXIE1,&IE2            ; Enable USART1 RX interrupt
                                            ;
Mainloop    bis.b   #CPUOFF+GIE,SR          ; Enter LPM0, interrupts enabled
            nop                             ; Needed 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