TD next - Community

Hello,

I am planing to use Real Time Clock (RTC) for my application and I have several questions:

- The XTAL 32Khz is the one used for Sleep Modes, right? so It is the one to use for periodic wake-ups, right?
- How accurate is the RTC?
- How often would i need to sync it via downlink message?

Regards, Ramon.

Hi Ramon,

The RTC is running at 32768 kHz on the internal Low-Frequency RC Oscillator (LFRCO), not on the "external" (well, inside the module!) Low-Frequency 32 kHz Crystal Oscillator (LFXO).

It is possible to calibrate the internal RC oscillator using the external crystal with the TD_RTC_CalibratedDelay() function or lower-level CMU_Calibrate() function.

According to EFM32G210 datasheet section 3.9.3, the LFRCO accuracy is +/-4.5% and tuning steps are 1.5% typical. That is, you may be off by approximately 1 h / day.

The sync period with downlink messages depends on your required accuracy.