Do anyone noted that the RTC_CLKIN and RTC_CLKOUT pins assignment on Kinetis?
For example, on KL25Z (LQFP80), RTC_CLKIN is assigned on pin1 and RTC_CLKOUT is assigned on pin pin56,
how to route if the user place one external 32k crystal in his PCB board?
Solved! Go to Solution.
Hi, Yu Jie
Pin RTC_CLKIN is used to provide clock source for RTC. Pin RTC_CLKOUT is a output of RTC clock. So if you want to give a clock source to RTC_CLKIN, I think you cannot use crystal but oscillator.
Hope my reply can help you.
Best Regards
Paul
Hi, Yu Jie
Pin RTC_CLKIN is used to provide clock source for RTC. Pin RTC_CLKOUT is a output of RTC clock. So if you want to give a clock source to RTC_CLKIN, I think you cannot use crystal but oscillator.
Hope my reply can help you.
Best Regards
Paul
Hi Paul,
Thanks for your quick respons.
It is a pity KL could only use one oscillator but not crystal, this would be high cost and high current consumption.
Thanks again.
Mark
You can use a crystal with the Kinetis oscillator, and clock the RTC from that. The oscillator uses the pins XTAL and EXTAL to connect to a crystal. In Kinetis L, the system oscillator can use a 32kHz crystal, and clock the RTC. Refer to the Clock Distribution chapter in the Reference Manual for more details
Yes Derek,but say that you want to use USB, that need 48MHz or submultiple of it,and RTC too..
I think that in this case at least an oscillator is needed
it could be for 32768 Hz for RTC_CLKIN or 48MHz for USB_CLKIN
Do you confirm?
Regards
Diego