When an RTC oscillator is present in the system, the CC3220x device can accept this clock directly as an input. The clock is fed on the RTC_XTAL_P line, and the RTC_XTAL_N line is held to VIO. The clock must be a CMOS-level clock compatible with VIO fed to the device.
Figure 8-10 shows the external RTC input connection.
Section 184.108.40.206.1 lists the external RTC digital clock requirements.