Can I exit STOP2 mode by going HIGH on the IRQ pin (If I have configured the IRQEDG = 1) IRQ is rising edge/high-level sensitive.
The manual on p.43 says
3.6.1.3 Exit from Stop2
Exit from stop2 is performed by asserting the wake-up pin (PTA5/IRQ/TCLK/RESET) on the MCU.
NOTE
PTA5/IRQ/TPM1CLK/RESET functions as an active-low wakeup input
when the MCU is in stop2. The pullup on this pin is not automatically
enabled in stop2. To enable the internal pullup, set the PTAPE5 bit in the
port A pull enable register (PTAPE).
p.47 says "Assert zero on PTA5/IRQ/TPM1CLK/RESET" to Transition from STOP2 to RUN
Then p.93 says
5.5.2.1 Pin Configuration Options
...As an IRQ input, the user can choose the polarity of edges or levels detected...
and p.98 even has a register for the Edge Select IRQEDG
Really misleading.
IRQ pin can be used to wake-up MCU from Stop3, the signal could be active low or active high desided how you config the IRQEDG.
But when IRQ pin is used to wake-up MCU from Stop2, the signal should be active_low only.