Batt_Check is ; called constantly in an endless loop - in an actual application, ; Batt_Check should be called very infrequently to save power.. ; ACLK = n/a, MCLK = SMCLK = default DCO
Trang 1; MSP430F20x1 Demo - Comp_A, Simple 2.2V Low Battery Detect
;
; Description: Two comparator_A reference generators 0.25*Vcc and ~ 0.55V
; are compared for a simple battery check of 2.2V In the subroutine
; Batt_Check a small capacitor that must be added to P2.3 is first charged
; to 0.25*Vcc and then compared to ~ 0.55V If 0.25*Vcc,
; is above ~0.55V, P1.0 is toggled, else set Batt_Check is
; called constantly in an endless loop - in an actual application,
; Batt_Check should be called very infrequently to save power
; ACLK = n/a, MCLK = SMCLK = default DCO
;
; There is a tolerence of the Comp_A reference generator and in the
; device specific datasheet In most applications, the tolerence of the
; reference generator is more than adequate to detect Low Battery
;
;
-; /|\ | XIN|-; | | |
; -|RST XOUT|-; | |
; + -|P1.1 P1.0| >LED ; | | |
; ===.1uf| |
; | | |
; + -|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 mov.w #WDTPW+WDTHOLD,&WDTCTL ; Stop WDT bis.b #001h,&P1DIR ; P1.0 output mov.b #P2CA4,&CACTL2 ; P1.1 = CA1 ;
Mainloop call #Batt_Check ;
jmp Mainloop ;
;
; -Batt_Check
mov.b #CAREF0+CAON,&CACTL1 ; 0.25*Vcc on P2.3, Comp on Wait clr.w R15 ; Delay to R15 L1 dec.w R15 ;
jnz L1 ; Delay over? mov.b #CARSEL+CAREF1+CAREF0+CAON,&CACTL1 ; 0.55V on -, Comp on bit.b #CAOUT,&CACTL2 ;
clr.b &CACTL1 ; Disable Comp_A, save power jnc Batt_Low ;
xor.b #001h,&P1OUT ; P1.0 toggle ret ;
Batt_Low bis.b #001h,&P1OUT ; P1.0 set ret
Trang 2; -; Interrupt Vectors
ORG 0FFFEh ; MSP430 RESET Vector
DW RESET ;
END