MK21 XTAL32 and Dryice questions

[PHXFAE]

I have 2 questions:

1. Is it possible to replace the 32KHz crystal with a MEMS crystal oscillator for the XTAL32 input for the RTC on this device?

.

2. Does the dryice require the XTAL32 clock to run if we just want the 32bytes of battery ram?

[Hui_Ma]

Hi Alex,

1.   I think a MEMS crystal oscillator as a external 32KHz clock source (oscillator) should works with RTC module.

I do a test with TWR-K40X256 board, using external signal generator output 32KHz clock as RTC reference clock input to EXTAL32 pin, and the RTC module works as expected.

2. The DryICE module clock source from RTC clock source, which still need external 32KHz clock when do any operation with DryICE module.

Wish it helps.

Have a great day,
Ma Hui

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[PHXFAE]

1.  Just to be clear, you connected the signal generator to the XTAL32 pin correct, not the EXTAL32 pin?  Can you please tell me the signal level you used and the VCC you were using for the K40 board?

2. You are saying that the RTC clock MUST be used when doing anything with DryICE, correct?

Thx for the help.

[PHXFAE]

I'm sorry. but I change the names around on number 1 above.  The question should read -.Just to be clear, you connected the signal generator to the EXTAL32 pin correct, not the XTAL32 pin?  Can you please tell me the signal level you used and the VCC you were using for the K40 board?

[Hui_Ma]

1.In fact, I had tested to connect external signal generator 32.768KHz clock to EXTAL32 and XTAL32 separately. The RTC module could work as expected.

While, for the EXTAL32 pin is input, we suggest customer to connect external clock source to EXTAL32 pin.

2. That's right.

Have a great day,
Ma Hui

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