an_compare.c

基于Atmel ATMega88+ATA682的应用实例 主要功能包括： 1) PWM输出控制 2) H-Bridge,4 POWER FET 驱动 3) 模拟量比较

/*
**
****************************************************************************
**
**
**             Copyright (c) 2007 - Atmel Corporation
**             Proprietaty Information
**
** Project    	: ATMEGA88 + ATA6824 High Temperature H-bridge System
** Module     	: an_compare.c
** Description	: Analog comparator is used to detect over-currents
**
**
** Version :     Date:         Author:      Comment:
**    1.0        05.03.2007    F.G.          Creation
**
** LICENSE -
**
** ATMEL - 2007
** All software programs are provided 'as is' without warranty of any kind:
** Atmel does not state the suitability of the provided materials for any
** purpose. Atmel hereby disclaim all warranties and conditions with regard
** to the provided software, including all implied warranties, fitness for
** a particular purpose, title and non-infringement.In no event will Atmel
** be liable for any indirect or consequential damages or any damages
** whatsoever resulting from the usage of the software program.
****************************************************************************
**
*/

/*_____ I N C L U D E S ____________________________________________________*/
#include "config.h"
#include "an_compare.h"
#include "Timer0_PWM.h"

/*_____ M A C R O S ________________________________________________________*/

/*_____ D E F I N I T I O N S ______________________________________________*/

/*_____ P R O T O T Y P E S - D E C L A R A T I O N ________________________*/

/*_____ G L O B A L S ______________________________________________________*/

over_current_t over_current; //! variable used to monitor over-current conditions



/*! @brief an_compare_init() initate the analog comparator to detect Over-currents
 *  Initialize Analog comparator:
 *  - Disable AIN0 and AIN1 (resp. PD6 and PD7) digital input buffers
 *  - Enable analog comparator to generates output toggle interrupts
 */
void AN_compare_init(void)
{
  DIDR1 = (1<<AIN1D) | (1<<AIN0D);  // Disable digital buffers on AIN1 and AIN0
                                    // to reduce power consumption
  ACSR  = (1<<ACIE);                // Enable Analog comparator interrupts
                                    // on compare output toggle
}


/*! @brief Over_current_ISR() comes as an over-current protection.
 *  Each transition around Over-current value (fixed by external reference)
 *  generate an interrupt.
 *  - When current increases above Over-current value, interrupt subroutine
 *  disables output PWM (pin is set to zero). It's reported in over_current
 *  variable.
 *  - When current decreases down to Over-current value, interrupt subroutine
 *  re-enables the output PWM.  It's reported in over_current variable.
 */
#if defined(__ICCAVR__)             //IAR COMPILER USED
#pragma vector= ANA_COMP_vect       //Analog comparator vector for ATmega88
__interrupt void Over_current_ISR (void)

#elif defined (__AVR__)             // Avr-gcc compiler used
ISR(ANALOG_COMP_vect)
#endif
{
  if (ACSR & (1<<ACO))
  {                                 // Input max current reference > current
    RE_ENABLE_OCB0();               // Restore PWM output control
    over_current.status = false;
  }
  else                              // Over-current condition
  {                                 // Current > max current reference
    DISABLE_OCB0();                 // Release OCB0, PWM output
    over_current.occured = true;
    over_current.status = true;
  }
}