Batt_Check is called // constantly in an endless loop - in an actual application, Batt_Check // should be called infrequently to save power.. // ACLK = n/a, MCLK = SMCLK = default DCO //
Trang 1//****************************************************************************** // MSP430G2x11 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 between P2.3 and Vss 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 infrequently to save power
// ACLK = n/a, MCLK = SMCLK = default DCO
//
// There is a tolerance 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
//
// MSP430G2x11
//
-// /|\ |
XIN|-// | | |
// -|RST
XOUT|-// | |
// + -|P1.1/CA1 P1.0| >LED
// | | |
// ===.1uf| |
// | | |
// + -|Vss
//
void Batt_Check(void);
unsigned int i;
//
// D Dang
// Texas Instruments Inc
// October 2010
// Built with CCS Version 4.2.0 and IAR Embedded Workbench Version: 5.10
//******************************************************************************
#include <msp430g2211.h>
void main (void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
P1DIR |= 0x01; // P1.0 output
CACTL2 = P2CA4; // P1.1 = CA1
while (1) // Mainloop
{
Batt_Check();
}
}
void Batt_Check(void) {
CACTL1 = CAREF_1 + CAON; // 0.25*Vcc on P1.1, Comp on
i = 16384; // delay
while(i>0) {
i ;
}
CACTL1 = CARSEL + CAREF_2 + CAREF_1 + CAON; // 0.55V on -, Comp on
if (CACTL2 & CAOUT)
P1OUT ^= 0x01; // P1.0 toggle
else P1OUT |= 0x01; // P1.0 set
CACTL1 = 0x00; // Disable Comp_A, save power
}