The RTC provides up to five selectable polarity external inputs (INn) that can be used for tamper detection. The following table shows number of tamper input pins available for different series of SAM L22 devices. The RTC also supports an input event (TAMPEVT) for generating a tamper condition from within the event system. Refer to the following figure.

A single interrupt request (TAMPER) is available for all tamper sources. The polarity for each input is selected with the Tamper Level bits in the Tamper Control register (TAMPCTRL.TAMPLVLn). The tamper input event is enabled by the Tamper Input Event Enable in the Event Control register (EVCTRL.TAMPEVIE). The action of each input pin is configured by using the Input n Action bits in the Tamper Control register (TAMPCTRL.INnACT).

Figure 1. Tamper Detection Block Diagram
Table 1. Tamper Input Pins Configuration Summary
Device SAM L22N SAM L22J SAM L22G
Tamper Input Pins 5 3 2