15.3.2.2 SAM L21/C20/C21 Clock Setup
The RTC clock can be selected from OSC32K, XOSC32K or OSCULP32K , and a 32KHz or 1KHz oscillator clock frequency is required. This clock must be configured and enabled in the 32KHz oscillator controller before using the RTC.
Table 15-3 lists the available RTC clock.
RTC clock frequency | Clock source | Description |
---|---|---|
1.024kHz | ULP1K | 1.024kHz from 32KHz internal ULP oscillator |
32.768kHz | ULP32K | 32.768kHz from 32KHz internal ULP oscillator |
1.024kHz | OSC1K | 1.024kHz from 32KHz internal oscillator |
32.768kHz | OSC32K | 32.768kHz from 3KkHz internal oscillator |
1.024kHz | XOSC1K | 1.024kHz from 32KHz internal oscillator |
32.768kHz | XOSC32K | 32.768kHz from 32KHz external crystal oscillator |