Here's the code after the sleep statement that shows the house keeping for waking up... continuing from previous post in this thread.
Note, I found the 328P waking up by itself when waving hands over the PCB, etc. Even after ensuring solid pullup resistors were attached to the I/O pins associated with the low level interrupts having the buttons on them. This was too flaky for belief, so I solved the problem using standard software debounce methods. Phantom button presses did not endure long enough (delay 5)... so the program just went back to sleep for those cases.
.... (within setup)
sleep_mode(); // here the device is actually goes to sleep, saving power
// THE PROGRAM CONTINUES HERE AFTER WAKING UP and running the attached interrupt routine.
// first thing after waking from sleep is disable sleep interrupts
noInterrupts();
sleep_disable();
detachInterrupt(0);
detachInterrupt(1);
interrupts();
// de-bounce / double-check here that button is still being pressed
delay(5); // bit of debounce time
if ( signalBits == B00100000 ) { // red button was pressed
if ( digitalRead(buttonRed) != LOW ) resleep(); // double check
if ( digitalRead(buttonRed) != LOW ) resleep(); // triple check
}
else if ( signalBits == B10000000 ) { // green button was pressed
if ( digitalRead(buttonGreen) != LOW ) resleep(); // double check
if ( digitalRead(buttonGreen) != LOW ) resleep(); // triple check
}
else resleep(); // transient interrupt didn't last as long as startup time, no button was pressed!
// I use the ADC, so I re-power the analog digital converter portion of MCU to get ready to read a POT
PRR = PRR & 0b11111110 ; // clear PRADC bit powers up this section of chip
ADCSRA = ADCSRA | 0b10000000 ; // set ADEN enables analog digital converter
.... (now do the real work of what your program is supposed to do)
And here's the resleep() routine, surprise, just sicks the watchdog to force a reset... and the setup begins again, going to sleep.
void resleep(){
// quick death by watchdog
wdt_enable(WDTO_15MS);
while(1) {
} // loop forever, but watchdog will bust this up