📄 fet110_ta_cap02.s43
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#include "msp430x11x1.h"
;******************************************************************************
; MSP-FET430x110 Demo - Timer_A Ultra-low Power 1800hz detect, SMCLK +/- 1%
;
; Description; Using Timer_A capture capability. At 128ms intervals,
; CCR0 is enabled on P2.2 to detect presence or absence of 1800Hz. If
; 1800Hz is present, P1.0 is set, if not, reset. Software FLL is use to set
; DCO (SMCLK)to 1MHz. WDT is used for 128ms second wake-up to hunt for
; tone. System runs normally in LPM3. Watch crystal is required for ACLK.
;
; 921600kHz = SMCLK = DCOCLK
; 1800Hz = 512 SMCLK clocks
; 1814Hz = 508 SMCLK clocks
; 1786Hz = 516 SMCLK clock
;
; MSP430F1121
; -----------------
; /|\| XIN|-
; | | | 32k
; --|RST XOUT|-
; | |
; Signal->|P2.2/CCR0 P1.0|-->LED
; | |
;
;
; CPU registers used
#define Period R15
#define OldCap R14
;
; User definitions
Delta equ 225 ; Target DCO Clock/(32768/8)
;
; M.Buccini
; Texas Instruments, Inc
; January 2002
;******************************************************************************
;------------------------------------------------------------------------------
ORG 0F000h ; Program Start
;------------------------------------------------------------------------------
RESET mov.w #300h,SP ; Initialize stackpointer
SetupBC bis.b #DIVA1+DIVA0,&BCSCTL1 ; ACLK=LFXT1CLK/8
SetupWDT mov.w #WDT_ADLY_16,&WDTCTL ; WDT 16ms*8 Interval Timer
bis.b #WDTIE,&IE1 ; Enable WDT Interrupt
SetupP1 mov.b #0FFh,&P1DIR ; All P1.x Outputs
clr.b &P1OUT ; All P1.x Reset
SetupP2 mov.b #0FBh,&P2DIR ; P2.2 Input / All P2.x Output
bis.b #004h,&P2SEL ; P2.2 CCR0 input
clr.b &P2OUT ; All P2.x Reset
call #Delay ; Time for crystal to stabilize ze
call #Set_DCO ; St DCO to target frequency
eint ; Enable Interrupts
;
Mainloop bis.w #LPM3,SR ; Enter LPM3
call #Get_CCR0 ; Capture CCR0 on P2.2
cmp.w #0516,Period ;
jhs OFF ;
cmp.w #0508,Period ;
jlo OFF ;
;
ON bis.b #001h,&P1OUT ; P1.0 = 1
jmp Mainloop ;
OFF bic.b #001h,&P1OUT ; P1.0 = 0
jmp Mainloop ;
;
;------------------------------------------------------------------------------
Get_CCR0; Subroutine to get CCR0 Capture
;------------------------------------------------------------------------------
clr.w Period ;
clr.w OldCap ;
mov.w #TASSEL1+TACLR,&TACTL ; SMCLK, TAR cleared
SetupC0 mov.w #CCIS0+CM0+CAP+CCIE+SCS,&CCTL0 ; CCI0B, CAP, interrupt
bis.w #MC1,&TACTL ; Start timer in Ccntinous mode
Test_1 cmp.w #02048,&TAR ; Timeout
jlo Test_1 ; jump if 02048 > &TAR
clr.w &TACTL ; Stop Timer_A
clr.w &CCTL0 ; Stop CCTL0
ret ;
;
;------------------------------------------------------------------------------
Delay; Software delay
;------------------------------------------------------------------------------
push.w #0FFFFh ; Delay to TOS
L1 dec.w 0(SP) ; Decrement TOS
jnz L1 ; Delay over?
incd.w SP ; Clean TOS
ret ;
;
;------------------------------------------------------------------------------
Set_DCO; Subroutine: Sets DCO to selected frequency based on Delta.
; R14 and R15 are used, ACLK= 32768/8 Timer_A clocked by DCOCLK
;------------------------------------------------------------------------------
clr.w R15 ;
Setup_TA mov.w #TASSEL1+TACLR,&TACTL ; SMCLK
Setup_CC2 mov.w #CCIS0+CM0+CAP,&CCTL2 ; Define CCR2,CAP,ACLK
bis.w #MC1,&TACTL ; Start timer_A: Continous Mode
Test_DCO bit.w #CCIFG,&CCTL2 ; Test capture flag
jz Test_DCO ;
bic.w #CCIFG,&CCTL2 ; Clear capture flag
;
AdjDCO mov.w &CCR2,R14 ; R14 = captured SMCLK
sub.w R15,R14 ; R14 = capture difference
mov.w &CCR2,R15 ; R15 = captured SMCLK
cmp.w #Delta,R14 ; Delta = SMCLK/(32768/8)
jlo IncDCO ;
jeq DoneDCO ;
DecDCO dec.b &DCOCTL ; Slow DCO with DCO and MOD
jnz Test_DCO ; Slower?
bit.b #07h,&BCSCTL1 ; Can RSEL.x be decremented?
jz DoneDCO ; jmp>DCO at slowest setting
dec.b &BCSCTL1 ; Decrement RSEL.x
jmp Test_DCO ;
IncDCO inc.b &DCOCTL ; Speed DCO with DCO and MOD
jnc Test_DCO ; Faster?
cmp.b #07h,&BCSCTL1 ; Can RSEL.x be increased?
jz DoneDCO ; jmp> DCO at fastest settting
inc.b &BCSCTL1 ; Increment RSEL.x
jmp Test_DCO ;
DoneDCO clr.w &CCTL2 ; Stop CCR2
clr.w &TACTL ; Stop timer_A
ret ; Return from subroutine
; ;
;-----------------------------------------------------------------------------
TA0_ISR; Timer_A C0 ISR
;-----------------------------------------------------------------------------
push.w &CCR0 ; Captured TAR, rising edge
mov.w @SP,Period ;
sub.w OldCap,Period ; New - old = period
pop.w OldCap ; For next calculation
reti ;
;
;------------------------------------------------------------------------------
WDT_ISR; Exit LPM3 on reti
;------------------------------------------------------------------------------
bic.w #LPM3,0(SP) ; Clear LPM3 from TOS
reti ;
;
;------------------------------------------------------------------------------
; Interrupt Vectors Used MSP430x11x1
;------------------------------------------------------------------------------
ORG 0FFFEh ; MSP430 RESET Vector
DW RESET ;
ORG 0FFF4h ; WDT Vector
DW WDT_ISR ;
ORG 0FFF2h ; Timer_A0 Vector
DW TA0_ISR ;
END
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