Substituting MK21 part for MK22 part

[matthew_pattiso]

Hi. I have a design based on the MK22FN512CAP12R but due to current procurement challenges I am considering using MK21FX512VMC12 instead. I do not need the extra security/tamper features that the MK21 family provides for this design. Is there an easy way to disable them? Any special strapping of the tamper pins?

Regards,

Matt

[Robin_Shen]

Hi Matt,

Regarding the unused tamper pins, it is okay to connect a 10K ohm pull-down resistor.
If the DryIce and RTC modules are not being used, leave the VBAT pin floating. VBAT must never be connected to ground.

The DryIce peripheral requires a 32kHz crystal connected to the RTC Oscillator to work.
The DryIce peripheral is powered from the VBAT rail.
There are bits in DryIce registers that actually enable the tamper functions. Until you hit those bits the input buffer is not actually enabled. The pins default to the tamper function, but you still have to use code before they are really enabled.

There are some difference between MK22FN512CAP12R and MK21FX512VMC12, please change the MCU by using MCUXpresso IDE.

Best Regards,
Robin
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