LPC1769 internal RTC is not working properly

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by Dhananjayan on Fri Nov 23 05:10:39 MST 2012
I am using LPC1769 microprocessor. I have set all the registers correctly and connected capacitor and crystal across the oscillator terminals.I have observed that RTC is working fine, RTC_OSCF bit is cleared (Bit 4) in RTC auxiliary control register and the seconds value is incrementing every second.

But after finishing the test and starting the test next day this flag seems to be set and does not clears after clearing the bit by writing one to clear the flag. Also seconds value does not incrementing.

I removed the capacitor and reconnected it. Now i found the RTC_OSCF bit is cleared and RTC is working fine.

This happens again and again when i started doing the RTC test.

I have connected ABS25 crystal oscillator (32.786KHz) to the internal oscillator pin RTCX1 and RTCX2.

I have used 22pF Capacitor across the terminals of oscillator.

Please suggest me some ideas to overcome this problem.