14.4.1.2 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.
The table below lists the available RTC clock Table 14-3.
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 32KHz internal oscillator |
1.024KHz | XOSC1K | 1.024KHz from 32KHz internal oscillator |
32.768KHz | XOSC32K | 32.768KHz from 32KHz external crystal oscillator |