;******************************************************************************
;   MSP430x42x0 Demo - SD16_A, Single Conversion on Single Channel Using ISR
;                         SMCLK input is divided by 32
;
;   Description: This program uses the SD16_A module to perform a single
;   conversion on a single channel. A SD16_A interrupt occurs when a
;   conversion has completed. Test by applying a voltage to CH0
;   (A0+, A0-) and setting a breakpoint at the line indicated below.
;   Run program until it reaches the breakpoint, then use the debugger's
;   register window to view the conversion results. The conversion result
;   for CH0 is stored in R12.
;   ACLK = LFXT1 = 32768Hz, MCLK = SMCLK = default DCO = 32 x ACLK = 1048576Hz
;   //* An external watch crystal between XIN & XOUT is required for ACLK *//	
;   //* Minimum Vcc is required for SD16_A module - see datasheet        *//
;   //* 100nF cap btw Vref and AVss is recommended when using 1.2V ref *//
;
;                 MSP430F4270
;              -----------------
;          /|\|              XIN|-
;           | |                 | 32kHz
;           --|RST          XOUT|-
;             |                 |
;     Vin+ -->|A0+              |
;     Vin- -->|A0-              |
;             |                 |
;             |            VREF |---+
;             |                 |   |
;             |                 |  -+- 100nF
;             |                 |  -+-
;             |                 |   |
;             |            AVss |---+
;             |                 |
;
;  L. Westlund / S. Karthikeyan
;  Texas Instruments Inc.
;  June 2005
;  Built with IAR Embedded Workbench Version: 3.30A
;******************************************************************************
#include  <msp430x42x0.h>

;-----------CPU Registers Used-------------------------------------------------
#define     RESULTS R12
                                            ; R12 - Store conversion result
                                            ; from SD16MEM2
;           R15 - Temporary working register

;------------------------------------------------------------------------------
            ORG     08000h                  ; Program Start
;------------------------------------------------------------------------------
RESET       mov.w   #300h,SP                ; Initialize stackpointer
StopWDT     mov.w   #WDTPW+WDTHOLD,&WDTCTL  ; Stop watchdog
SetupFLL    bis.b   #XCAP14PF,&FLL_CTL0     ; Configure load caps
            mov.w   #10000,R15              ;
Xtal_Wait   dec.w   R15                     ; Delay for 32 kHz crystal to
            jnz     Xtal_Wait		    ; stabilize
SetupSD16   mov.w   #SD16REFON+SD16SSEL0+SD16DIV0+SD16XDIV1,&SD16CTL ; 1.2V ref, SMCLK/2/16
            bis.w   #SD16SNGL+SD16IE,&SD16CCTL0 ; Single conv, enable interrupt, high impedance
            bis.b   #SD16INTDLY_0,&SD16INCTL0; 4th sample generates interrupt
            mov.w   #03600h,R15             ; Delay needed for 1.2V ref startup
L$1         dec.w   R15                     ;
            jnz     L$1                     ;
            eint                            ; Enable general interrupts
Mainloop    bis.w   #SD16SC,&SD16CCTL0      ; Start conversion
            bis.w   #CPUOFF,SR              ; Enter LPM0 (disable CPU), wait for
                                            ; conversion to complete
            nop                             ; Required for debug only
            jmp     Mainloop                ; SET BREAKPOINT HERE
                                            ;
;------------------------------------------------------------------------------
SD16_ISR    ; SD16_A Interrupt Service Routine
;------------------------------------------------------------------------------
            add.w   &SD16IV,PC              ; Add offset to PC
            reti                            ; Vector 0: No interrupt
            jmp     SD_OV                   ; Vector 2: Overflow
            jmp     SD_CH0                  ; Vector 4: IFG
                                            ;
;-----------SD16_A Interrupt Handler-------------------------------------------
SD_CH0      mov.w   &SD16MEM0,RESULTS       ; Save CH0 conversion result
            bic.w   #CPUOFF,0(SP)           ; Return active
SD_CH0_END  reti                            ; Return from interrupt
                                            ;
;-----------SD16_A Memory Overflow Interrupt Handler---------------------------
SD_OV       reti                            ; Return from interrupt
                                            ;

;------------------------------------------------------------------------------
;           Interrupt Vectors
;------------------------------------------------------------------------------
            ORG     0FFFEh                  ; RESET Vector
            DW      RESET                   ;
            ORG     0FFF8h                  ; SD16_A Vector
            DW      SD16_ISR                ;
            END