;******************************************************************************
;   MSP-FET430P140 Demo - USART0 SPI Interface to TLV5516 DAC
;
;   Description: Demonstrate USART0 in SPI mode interface to TLV5516 DAC. 
;   USART0 is used to transmit data to DAC, Timer_A CCR1/CCRO used to generate 
;   frame sync pulse, DAC is updated inside CCR0 ISR. R5 used as pointer 
;   into Sin_tab.  
;   ACLK = MCLK = LFXT1 = HF XTAL = 3.58MHz, UCLK0 = LFXT1/2
;   //** SWRST** please see MSP430x1xx Users Guide for description **//
;   //** USART0 control bits are in different SFR's from other MSP430's **// 
;   //** 3.58Mhz XTAL CRYSTAL REQUIRED - NOT INSTALLED ON FET **// 
;
;                MSP430F149             
;             -----------------
;         /|\|              XIN|-  
;          | |                 | 3.58MHz   TLV5616
;          --|RST          XOUT|-       -------------
;            |             P2.3|------>|FS        OUT|--> ~ 1kHz sine wave
;            |       SIMO0/P3.1|------>|DIN          |
;            |       UCLK0/P3.3|------>|SCLK       CS|-|
;            |                 |       |             | v
;
;
;   M.Buccini
;   Texas Instruments, Inc
;   January 2004
;******************************************************************************
#include  "msp430x14x.h"
;------------------------------------------------------------------------------ 
            ORG     01100h                  ; Progam Start 
;------------------------------------------------------------------------------ 
RESET       mov.w   #0A00h,SP               ; Initialize 'F1x9 stackpointer
StopWDT     mov.w   #WDTPW+WDTHOLD,&WDTCTL  ; Stop watchdog timer
SetupP3     bis.b   #0Ah,&P3SEL             ; P3.1,3 SPI option select
            bis.b   #0Ah,&P3DIR             ; P3.1,3 output direction
SetupP2     bis.b   #08h,&P2SEL             ; P2.3 CCR1 option select
            bis.b   #08h,&P2DIR             ; P2.3 output
SetupBC     bis.b   #XTS,&BCSCTL1           ; ACLK = LFXT1 = HF XTAL
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   #SELM1+SELM0,&BCSCTL2   ; MCLK = LFXT1
SetupSPI    bis.b   #USPIE0,&ME1            ; Enable USART0 SPI
            bis.b   #CHAR+SYNC+MM,&UCTL0    ; 8-bit SPI Master **SWRST**
            mov.b   #CKPH+CKPL+SSEL0+STC,&UTCTL0 ; Inv. delayed, ACLK,3-pin
            mov.b   #02h,&UBR00             ; ACLK/2 for baud rate
            clr.b   &UBR10                  ; ACLK/2 for baud rate
            clr.b   &UMCTL0                 ; Clear modulation
            bic.b   #SWRST,&UCTL0           ; **Initialize USART state machine**
            clr.w   R5                      ; Clear pointer
SetupC1     mov.w   #OUTMOD_7,&CCTL1        ; CCR1 reset/set
            mov.w   #01,&CCR1               ; CCR1 PWM Duty Cycle	  
SetupC0     mov.w   #CCIE,&CCTL0            ; CCR0 interrupt enabled
            mov.w   #111-1,&CCR0            ; Clock period of CCR0 
SetupTA     mov.w   #TASSEL_1+MC_1,&TACTL   ; ACLK, upmode
                                            ;
Mainloop    bis.b   #CPUOFF+GIE,SR          ; Enter LPM0, enable interrupts
            nop                             ; Needed only for debugger
                                            ;
;------------------------------------------------------------------------------ 
TA0_ISR;    Timer_A CCR0 ISR  
;           SPI buffer TXBUF0 needs to be ready prior to writing, with 
;           UCLK0 = MCLK/2 it is safe to write back to back as first word 
;           transfers in two clocks, faster than.b mov operation.
;------------------------------------------------------------------------------ 
            mov.b   Sin_tab+1(R5),&TXBUF0   ; High byte to SPI TXBUF
            mov.b   Sin_tab(R5),&TXBUF0     ; Low byte to SPI TXBUF
            incd.w  R5                      ; Inc pointer
            and.w   #03Eh,R5                ; R5 = 0 - 62 only (32 words)             
            reti                            ; Return from interupt
                                            ;
;------------------------------------------------------------------------------ 
; 12-bit Sine Lookup table with 32 steps
;------------------------------------------------------------------------------ 
Sin_tab     DW       2048
            DW       2447
            DW       2831
            DW       3185
            DW       3495
            DW       3750
            DW       3939
            DW       4056
            DW       4095
            DW       4056
            DW       3939
            DW       3750
            DW       3495
            DW       3185
            DW       2831
            DW       2447
            DW       2048
            DW       1648
            DW       1264
            DW       910
            DW       600
            DW       345
            DW       156
            DW       39
            DW       0
            DW       39
            DW       156
            DW       345
            DW       600
            DW       910
            DW       1264
            DW       1648
;
;------------------------------------------------------------------------------ 
;           Interrupt Vectors Used MSP430x13x/14x/15x/16x         
;------------------------------------------------------------------------------ 
             ORG     0FFECh                  ; Timer_A3 CCIFG0
             DW      TA0_ISR                 ; 
             ORG     0FFFEh                  ; POR, ext. Reset, Watchdog, Flash
             DW      RESET                   ; 
             END