Using an ; external potentiometer, an unknown analog voltage is applied to P1.1.. ; Comparator_A compares the unknown voltage to an internal reference ; voltage, in this example 0.25*VCC
Trang 1; MSP430F20x1 Demo - Comp_A, Detect Threshold, Set P1.0 if P1.1 > 0.25*Vcc
;
; Description: Use comparator_A to detect a voltage threshold Using an
; external potentiometer, an unknown analog voltage is applied to P1.1
; Comparator_A compares the unknown voltage to an internal reference
; voltage, in this example 0.25*VCC If the interesting voltage is higher
; than 0.25*Vcc, P1.0 is set, if not, P1.0 is reset
; ACLK = n/a, MCLK = SMCLK = default
;
; MSP430F20x1
;
-; /|\ |
XIN|-; | | |
; -|RST
XOUT|-; | | |
; R<-|P1.1/CA1 P1.0| > LED
; | | |
; -|VSS
;
; M Buccini / L Westlund
; Texas Instruments Inc
; December 2005
; Built with IAR Embedded Workbench Version: 3.40A
;*******************************************************************************
#include "msp430x20x1.h"
ORG 0F800h ; Program Reset
; -RESET mov.w #0280h,SP ; Initialize stackpointer
StopWDT mov.w #WDTPW+WDTHOLD,&WDTCTL ; Stop WDT
SetupP1 bis.b #001h,&P1DIR ; P1.0 = output
mov.b #CARSEL+CAREF0+CAON,&CACTL1 ; 0.25Vcc = -comp, on
mov.b #P2CA4,&CACTL2 ; P1.1/CA1 = +comp
;
Mainloop bit.b #CAOUT,&CACTL2 ; Test comparator_A output
jz OFF ; jmp > if CAOUT reset
;
ON bis.b #001h,&P1OUT ; P1.0 = 1
jmp Mainloop ;
OFF bic.b #001h,&P1OUT ; P1.0 = 0
jmp Mainloop ;
;
; -; Interrupt Vectors
ORG 0FFFEh ; MSP430 RESET Vector
DW RESET ;
END