I don't have the 32kHz xtal on my PCB but need a good RTC on a subset of my boards. My plan was to derive the LF clock from the XOSC_HF but I found that it is less accurate (~10s drift per day). I used the following code to force the use of the XOSC_HF:
Power_setConstraint(PowerCC26XX_SD_DISALLOW); Power_setConstraint(PowerCC26XX_SB_DISALLOW); Power_setConstraint(PowerCC26XX_IDLE_PD_DISALLOW);
If I use the default power policy (allowing standby mode) and the RCOSC as the LF clock source, I get ~3s drift per day. My first question is why... but also, if the XOSC_HF is not accurate and Calibrate RCOSC_XX is enabled in my Power Driver, I would almost expect the RCOSC to drift more. I'm seeking a practical solution for deploying many devices: if this is best resolved by [6.4] Tuning the HF Oscillator, should I expect that to be more dependent on individual devices/crystals (calibrate each one) or my PCB layout (find one ideal calibration value)?
Also, can I output the derived 32kHz signal on a GPIO? Maybe this will be helpful.
