msp430x20x1 ca 02 _Code mẫu

// Using an external potentiometer, an unknown voltage is applied to P1.1.. // Comparator_A compares the unknown voltage to an internal reference // voltage, in this example 0.25*VCC.. W

//****************************************************************************** // 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 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 unknown voltage is higher

// than 0.25*VCC, P1.0 is set, if not, P1.0 is reset

// ACLK = n/a, MCLK = SMCLK = default DCO

//

// MSP430F20x1

//

-// /|\ |

XIN|-// | | |

// -|RST

XOUT|-// | | |

// R<-|P1.1/CA1 P1.0| >LED

// | | |

// -|VSS

//

// M Buccini / L Westlund

// Texas Instruments Inc

// December 2005

// Built with CCE Version: 3.2.0 and IAR Embedded Workbench Version: 3.40A

//******************************************************************************

#include <msp430x20x1.h>

void main (void)

{

WDTCTL = WDTPW + WDTHOLD; // Stop WDT

P1DIR |= 0x01; // P1.0 output

CACTL1 = CARSEL + CAREF0 + CAON; // 0.25 Vcc = -comp, on

CACTL2 = P2CA4; // P1.1/CA1 = +comp

while (1) // Test comparator_A output

{

if ((CAOUT & CACTL2))

P1OUT |= 0x01; // if CAOUT set, set P1.0

else P1OUT &= ~0x01; // else reset

}

}

//****************************************************************************** // 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 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 //

//

-// /|\ |

XIN|-// | | |

// -|RST

XOUT|-// | |

// + -|P1.1/CA1 P1.0| >LED

// | | |

// ===.1uf| |

// | | |

// + -|Vss

//

void Batt_Check(void);

unsigned int i;

//

// M Buccini / L Westlund

// Texas Instruments Inc

// December 2005

// Built with CCE Version: 3.2.0 and IAR Embedded Workbench Version: 3.40A

//******************************************************************************

#include <msp430x20x1.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 }