I want to build small RF remote that works off 3V coin cell. ATTiny84 seems like a good candidate. To save battery power, IC will be sleeping, only being awakened by external interrupt (button). Problem is I want to use several buttons. From pinout it looks like ATTiny84 has at least 10 usable hardware interrupts (wow that a lot more than ATMega328p) if I'm reading it correctly. Would I be able to wake chip if by several buttons that attached to those pins? Also how do you debounce those buttons, since millis is not working in ISR function?
You might also be able to use single terminal switches connected to both the button pin and the hardware interrupt pin via diodes to stop volts going back to other switches.
The Tiny84 is similar, it can interrupt on any pin but pin 5 (PB2) is special, it has its own interrupt vector (INT0). Unfortunately, this is the only pin that can wake up the chip when it's sleeping.