17.3.3.1 Asynchronous Sensing Pin Properties
All PORT pins support asynchronous input sensing with interrupts for selectable pin change conditions. Fully asynchronous pin change sensing can trigger an interrupt and wake the device from all sleep modes, including modes where the Peripheral Clock (CLK_PER) is stopped, while partially asynchronous pin change sensing is limited as per the table below. See the I/O Multiplexing and Considerations section for further details on which pins support fully asynchronous pin change sensing.
| Property | Partially Asynchronous Pins | Fully Asynchronous Pins |
|---|---|---|
| Waking the device from sleep modes with CLK_PER running | From all interrupt sense configurations | From all interrupt sense configurations |
| Waking the device from sleep modes with CLK_PER stopped | Only from BOTHEDGES or LEVEL interrupt sense configurations | |
| Minimum pulse-width to trigger an interrupt with CLK_PER running | Minimum one CLK_PER cycle | Less than one CLK_PER cycle |
| Minimum pulse-width to trigger an interrupt with CLK_PER stopped | The pin value must be kept until CLK_PER has restarted(1) | |
| Interrupt “dead-time” | No new interrupt for three CLK_PER cycles after the previous |
Note:
- If a partially asynchronous input pin is used for wake-up from sleep with CLK_PER stopped, the required level must be held long enough for the MCU to complete the wake-up to trigger the interrupt. If the level disappears, the MCU can wake up without any interrupt generated.