Kinetis MicrocontrollersのトピックRe: FRDM-K64F RTC working?

FRDM-K64F RTC working?

haizhouli — Wed, 15 Oct 2014 16:28:49 GMT

Hello there,

I am using FRDM-K64F as a prototype board for RTC test. I used PE to program rtc, but the clock seems not running. I am using an oscilloscope to check the 32K crystal. I can see both the 8MHz and 25Mhz on board. But no oscillation on 32K crystal at all.

Has anyone worked on FRDM-K64F RTC before? I had three FRDM boards and none has oscillation. Do I need pop those caps and resistors based on the schematics

Thanks!

Haizhou

Re: FRDM-K64F RTC working?

mjbcswitzerland — Wed, 15 Oct 2014 16:59:35 GMT

It is not necessary to add any capacitors to use the RTC:

Make sure that the RTC uis powered up (RTC bit in SIM_SCGC6) and its clock source correctly selected (in RTC_SC) and enabled in RTC_CR. The DC level on the pins will then increase form 0V to about mid-voltage and the 32kHz will be present.

Regards

Mark

Re: FRDM-K64F RTC working?

haizhouli — Wed, 15 Oct 2014 20:57:53 GMT

Thanks Mark,

Yes, once the setup was right, I can detect the 32K oscillation.