I have 10 devices with LPC11u67 on them. 4 of these devices has failing RTC clock - I've tried resoldering RTC crystal, checked the battery with no luck. The strange thing is, that if I connect signal generator (square, about 30 kHz) and put the probe on RTC Xtal pins, it fixes the problem permenantly (well I hope so). When debugged, peripheral registers of RTC shows OFD bit set and marked as "FAIL". Clearing this bit does nothing at all. Datasheet, User Manual and Errata didn't help with this. So my question is: Is it Hardware problem? What is the meaning of OFD bit? is there any way of fixing it with firmware?