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MK20DX128vlh7 reseting

Question asked by Neil Hancock on Nov 18, 2014
Latest reply on Nov 24, 2014 by Neil Hancock

Hi, I'm bring up a new board with an MK20DX128VLH7 2N36B

The reset line RESET_b/pin34 is continuously asserting for 50uS, releasing ~2us, and then asserting.

 

I have a

R=10K toV3v on EZP_CS/NMI_b/PTA4 pin 26

R=100K to V3v SWD_DIO /Pta3   pin 25

I've verified the Power - Vout33 goes to VddA/VRefH/0.1uF, then 47nH to Vbat/Vdd with 0.1uF on each pin - noise on all pwr sply appears less than 5mV

No funny/50uS signals on any other pin.

If I force the EZP-CS low - then it doesn't continuously reset, I guess having entered the EZPort boot.

 

Should I be forcing any other pins to a known state to prevent it reseting?

Any insights appreciated.

 

Once it stops resetting I have a Segger JLink to program it, however currently the JLink can't access it.

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