change_wakeup.c - wake from sleep using a change notification interrupt

Demonstrates the use of change notification interrupt to wake from Sleep mode. A pushbutton on a change notfication pin will be used to wake the from Sleep mode.

 
#include "pic24_all.h"
 
 

Interrupt Service Routine for Change Notification

void _ISRFAST _CNInterrupt(void) {

Clear the change notification interrupt bit.

  _CNIF = 0;
}
 

Pushbutton configuration: assumes PB is on RB13.

void config_pb(void)  {
  CONFIG_RB13_AS_DIG_INPUT();
  ENABLE_RB13_PULLUP();
  ENABLE_RB13_CN_INTERRUPT();

Wait for pull-up to take effect.

  DELAY_US(1);
}

int main(void) {
  configBasic(HELLO_MSG);
  /** Configure the switch ***********/
  config_pb();  //enables individual CN interrupt also
  /** Configure Change Notification general interrupt  */
  _CNIF = 0;         //Clear the interrupt flag
  _CNIP = 2;         //Choose a priority > 0
  _CNIE = 1;         //enable the Change Notification general interrupt
  while (1) {
    outString("Entering Sleep mode. Press button to wake.\n");

Finish sending characters before sleeping

    WAIT_UNTIL_TRANSMIT_COMPLETE_UART1();
    SLEEP();         //macro for asm("pwrsav #0")
  }
}