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Cameron
2018-03-18 00:56:37 -04:00
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content/dxp_Lab7_a1.asm Normal file
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;-------------------------------------------------------------------------------
; MSP430 Assembler Code Template for use with TI Code Composer Studio
; Toggles the center LED when center "key" on the capacitive touch sensor
; is "pressed"
;-------------------------------------------------------------------------------
.cdecls C,LIST,"msp430.h" ; Include device header file
SWdelay .equ 0x0002 ; delay value used by the SW timer
;-------------------------------------------------------------------------------
; Allocate 2 bytes for the baseline measurement
;-------------------------------------------------------------------------------
.data
.bss meas_base, 2 ;
;-------------------------------------------------------------------------------
; Allocate another 2 bytes for the current measurement
;-------------------------------------------------------------------------------
.bss meas_crt, 2 ;
;-------------------------------------------------------------------------------
.text ; Assemble into program memory
.retain ; Override ELF conditional linking
; and retain current section
.retainrefs ; Additionally retain any sections
; that have references to current
; section
;-------------------------------------------------------------------------------
RESET mov.w #__STACK_END,SP ; Initialize stackpointer
StopWDT mov.w #WDTPW|WDTHOLD,&WDTCTL ; Stop watchdog timer
;-------------------------------------------------------------------------------
; Main loop from here
;-------------------------------------------------------------------------------
; Setting up P1.0 to drive center LED
;-------------------------------------------------------------------------------
bis.b #0xff, &P1DIR ; set up P1 as outputs
bic.b #0xff, &P1OUT ; P1 outputs 0
;-------------------------------------------------------------------------------
; Setting up P2.5 to pin oscillation mode
;-------------------------------------------------------------------------------
bic.b #BIT5,&P2DIR ; P2.5 input
bic.b #BIT5,&P2SEL ;
bis.b #BIT5,&P2SEL2 ;
;-------------------------------------------------------------------------------
; The oscillation from P2.5 is driving INCLK input of TA0
; No division of this clock source
;-------------------------------------------------------------------------------
mov #TASSEL_3, &TA0CTL ;
;-------------------------------------------------------------------------------
; Setting up to capture the value of TAR on either rising or falling edges
; using SW based trigger
;-------------------------------------------------------------------------------
mov #CM_3 + CCIS_2 + CAP, &TA0CCTL1 ;
;-------------------------------------------------------------------------------
; Get the baseline reading
;-------------------------------------------------------------------------------
; Clear TAR and start TA0 in continuous mode; use BIS and not MOV
; so that you don't cancel previous settings
;-------------------------------------------------------------------------------
bis #MC_2 + TACLR, &TA0CTL ;
;-------------------------------------------------------------------------------
; Call the SW delay routine, which here it is used to provide the accumulation
; period; could use instead ACLK fed from VLO
;-------------------------------------------------------------------------------
call #SWtimer ;
;-------------------------------------------------------------------------------
; Now, after the accumulation period has passed, generate a SW based
; capture trigger by toggeling CCIS0
;-------------------------------------------------------------------------------
xor #CCIS0, &TA0CCTL1 ;
;-------------------------------------------------------------------------------
; Save the baseline captured value in meas_base
;-------------------------------------------------------------------------------
mov TA0CCR1, meas_base ; note the use of the SYMBOLIC AM
bic #MC1+MC0, &TA0CTL ; Stop TA
sub #2, meas_base ; Adjust the baseline
;-------------------------------------------------------------------------------
; From here on check again and again the status of the sensor
; If it was "pressed", i.e. meas_crt =/= meas_base, toggle the central LED
;-------------------------------------------------------------------------------
CheckAgain bis #TACLR, &TA0CTL ; Clear TAR
bis #MC_2, &TA0CTL ; Continuous Mode
call #SWtimer ;
xor #CCIS0, &TA0CCTL1 ;
mov TA0CCR1, meas_crt ;
bic #MC1+MC0, &TA0CTL ;
cmp meas_crt, meas_base ;
jn NoKey ;
xor #1, P1OUT ; Toogle center LED on key "pressed"
NoKey nop ; Could do a lot of useful things here
jmp CheckAgain ;
;-------------------------------------------------------------------------------
SWtimer: mov #SWdelay, r6 ; Load delay value in r5
Reloadr5 mov #SWdelay, r5 ; Load delay value in r6
ISr50 dec r5 ; Keep this PW for some time
jnz ISr50 ; The total SW delay count is
dec r6 ; = SWdelay * SWdelay
jnz Reloadr5 ;
ret ; Return from this subroutine
;-------------------------------------------------------------------------------
; Stack Pointer definition
;-------------------------------------------------------------------------------
.global __STACK_END
.sect .stack
;-------------------------------------------------------------------------------
; Interrupt Vectors
;-------------------------------------------------------------------------------
.sect ".reset" ; MSP430 RESET Vector
.short RESET