📄 fet110_ca_05.s43
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;******************************************************************************
; MSP-FET430x110 Demo - Comp_A, Thermometer 59-99 F
;
; Description: Comparator_A is used to measure a resistance value of
; an 10k-NTC (25c) and converted to temperature (oF). Discharge times
; of a 0.1uf capacitor through a 10k-NTC (25C) and 10k ohm reference
; resistor are measured using Timer_A CCR1. The times are compared
; and the ratio converted to an absolute temperature. The resulting
; temperature is placed in R11 (59 - 99).
; ACLK = n/a, MCLK = SMCLK = default DCO ~800k
;
; MSP430F1121
; -----------------
; /|\ | XIN|-
; | | |
; ---|RST XOUT|-
; | |
; +-10k-|P2.0 |
; | | |
; +-NTC-|P2.1 |
; | | |
; +-----|P2.3 |
; | | |
; ===.1uf| |
; | | |
; ------|VSS
;
; NTC = 10k @25c, (P/N 271-110A Radio Shack)
;
Ref EQU 001h ; P2.0 = Reference
Sensor EQU 002h ; P2.1 = Sensor
;
; M. Buccini
; Texas Instruments Inc.
; Feb 2005
; Built with IAR Embedded Workbench Version: 3.21A
;*****************************************************************************
#include <msp430x11x1.h>
;------------------------------------------------------------------------------
ORG 0F000h ; Program Start
;------------------------------------------------------------------------------
RESET mov.w #300h,SP ; Initialize stackpointer
mov.w #WDTPW+WDTHOLD,&WDTCTL ; Stop Watchdog Timer
bic.b #Sensor+Ref,&P2OUT ; Sensor, Ref reset
bic.b #Sensor+Ref,&P2DIR ; Sensor, Ref input
mov.b #008h, &CAPD ; Disconnect port pins
mov.b #CARSEL+CAREF0+CAON,&CACTL1 ; -Comp = 0.25*Vcc - on
mov.b #P2CA0,&CACTL2 ; +Comp = P2.3
mov.w #TASSEL_2+MC_2,&TACTL ; SMCLK, contmode
eint ; General interrupt enable
;
Mainloop mov.w #Sensor,R14 ; R14 = discharge pin
call #Measure ; R14 = Sensor discarge time
mov.w R14,R11 ; R11 = Sensor discharge time
mov.w #Ref,R14 ; R14 = discharge pin
call #Measure ; R14 = Ref discharge time
push.w R14 ; TOS = Ref discharge time
;
;Calculate mov.w #10000,R12 ;
Calculate mov.w #09870,R12 ;
call #MPYU ; Sensor (R11)*10000 = R15 | 14
pop.w R11 ; R11 = Ref discharge time
mov.w R14,R12 ;
mov.w R15,R13 ;
call #DIVIDE ; R14 = Sensor*10000/Ref
call #RES_2_F ; R11 = oF
jmp Mainloop ; Repeat
;
;------------------------------------------------------------------------------
Measure; Input: R14 = Sensor or Ref P2.x bit location
; Output: R14 = Sensor or Ref discharge time
;------------------------------------------------------------------------------
Charge; Capacitor is charged via Ref
bis.b #Ref,&P2OUT ; Ref Set
bis.b #Ref,&P2DIR ; Ref output
mov.w #TAR,&CCR1 ; CCR1 = TAR
add.w #5000,&CCR1 ; CCR1 ~ TAR+5ms (5tu)
mov.w #CCIE,&CCTL1 ; Compare mode,interrupt enable
bis.w #LPM0,SR ; Wait for CCR1 interrupt
bic.b #Ref,&P2DIR ; Ref = HiZ, Charge complete
bic.b #Ref,&P2OUT ; Ref = Reset
Discharge; Measure Discharge Time
mov.w #CM_2+CCIS_1+CAP+CCIE,&CCTL1 ; Neg, CCIB,Cap,interrupt
push.w &TAR ; TOS = TAR at SOC
bis.b R14,&P2DIR ; R14 = Sensor or REF
bis.w #LPM0,SR ; Wait for CCR1 interrupt
mov.w &CCR1,R14 ; R14 = TAR (CCR1) at EOC
sub.w @SP+,R14 ; R14 = discharge time
bic.b #Sensor+Ref,&P2DIR ; Disable Sensor or Ref
clr.w &CCTL1 ; Disable CCTL1
ret ; Return from subroutine
;
;------------------------------------------------------------------------------
MPYU ; Unsigned Multipy R11 x R12 = R15 | R14
; Input: R11, R12 , R10 = working register
; Output: R15, R14
;------------------------------------------------------------------------------
clr.w R14 ; 0 -> LSBs result
clr.w R15 ; 0 -> MSBs result
MACU clr.w R13 ; MSBs multiplier
mov.w #1,R10 ; bit test register
MPY2 bit.w R10,R11 ; test actual bit
jz MPY1 ; IF 0: do nothing
add.w R12,R14 ; IF 1: add multiplier to result
addc.w R13,R15 ;
MPY1 rla.w R12 ; multiplier x 2
rlc.w R13 ;
rla.w R10 ; next bit to test
jnc MPY2 ; if bit in carry: finished
ret ; Return from subroutine
;
;------------------------------------------------------------------------------
DIVIDE ; Unsigned 32/16 divide R13 | R12 / R11 = R14
; Input: R13, R12, R10 is a working register
; Output: R14
;------------------------------------------------------------------------------
clr.w R14 ; Clear Accumulator Low
mov.w #17,R10 ; Initalize Loop Counter
DIV1 cmp.w R11,R13 ;
jlo DIV2 ;
sub.w R11,R13 ;
DIV2 rlc.w R14 ;
jc DIV4 ; Error: result > 16 bits
dec.w R10 ; Decrement loop counter
jz DIV4 ; Is 0: terminate w/o err
rla.w R12 ;
rlc.w R13 ;
jnc DIV1 ;
sub.w R11,R13 ;
setc ;
jmp DIV2 ;
DIV4 ret ; Error indication in C
;
;------------------------------------------------------------------------------
RES_2_F; Convert Resistance (R14) to Degrees F (R11) using RES_TAB
; Input: R14, R12 is a working register
; Output: R11
;------------------------------------------------------------------------------
clr.w R12 ; R12 Used as Pointer
mov.w #99h,R11 ; R11 Used as Temperature Counter
CMPR cmp.w RES_TAB(R12),R14 ; Compare Table Value to Sensor
jlo End_RES_2_F ; Jump if Sensor < Table
incd.w R12 ; Increment word Pointer
dadd.b #99h,R11 ; Subtract 1 from Counter
jmp CMPR ;
End_RES_2_F ret ; Return from subroutine
;
;------------------------------------------------------------------------------
TAX_ISR; Common ISR for CCR1-4 and overflow
;------------------------------------------------------------------------------
add.w &TAIV,PC ; Add TA interrupt offset to PC
reti ; CCR0 - no source
jmp CCR1_ISR ; CCR1
; reti ; CCR2
; reti ; CCR3
; reti ; CCR4
;TA_over reti ; Timer_A overflow
;
CCR1_ISR bic.w #LPM0,0(SP) ; Exit LPM0 on reti
reti ;
;
;------------------------------------------------------------------------------
; Resistance table, K ohms to 99-59 degrees F.
;------------------------------------------------------------------------------
RES_TAB even ; Evenly aligned
DW 6446 ;99 F
DW 6570
DW 6693
DW 6817 ;96 F
DW 6941 ;95 F
DW 7093
DW 7245
DW 7398
DW 7550
DW 7703 ;90 F
DW 7856
DW 8008
DW 8161
DW 8313
DW 8500 ;85 F
DW 8688
DW 8875
DW 9063
DW 9250
DW 9438 ;80 F
DW 9625
DW 9813
DW 10000
DW 10232
DW 10464 ;75 F
DW 10697
DW 10929
DW 11161
DW 11393
DW 11626 ;70 F
DW 11858
DW 12090
DW 12378
DW 12666
DW 12953 ;65 F
DW 13241 ;64 F
DW 13529
DW 13817
DW 14104
DW 14392
DW 14680 ;59 F
;
;------------------------------------------------------------------------------
; Interrupt Vectors
;------------------------------------------------------------------------------
ORG 0FFFEh ; MSP430 RESET Vector
DW RESET ;
ORG 0FFF0h ; Timer_AX Vector
DW TAX_ISR ;
END
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