AnsweredAssumed Answered

How to use LPC4357 RTC?

Question asked by uaz on Mar 12, 2019
Latest reply on Mar 18, 2019 by jeremyzhou



Is there any guide on how to use LPC4357 RTC correctly?

I'm having many issues with the RTC:

1. Using 32.768khz crystal: everytime I update RTC time, the cpu will become glitchy. My freertos will freeze for 1-2 seconds. I tried without RTC, no issue with my freertos. Then I realised about the errata which might cause this issue.


2. Using external 32.768khz oscillator (connected to RTCX1, RTCX2 open): Unable to countdown LPC_ATIMER->DOWNCOUNTER. Looks like rtc peripheral is not getting the clock signal


How do I configure external the external oscillator? I can't find any info, and I just use the same CREG0 clock setting as the crystal.


Can you recommend an external oscillator that can work straight away with this MCU?