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MK20DX256VLH7 locked/problems mass erasing

Question asked by Mario Gongora on Nov 20, 2015
Latest reply on Jan 4, 2016 by Mario Gongora

Hi everybody, I am developing my own k20 board specifically with mk20dx256vlh7, my problem is that I have already mass erased 2 chips ( first to do before debug and program), but I must have erase (and program) 4 more, I am doing same process as 2 I have already erased but without good results with 4 chips.


By reading posts and documentation I know that maybe it's a registers issue, but cartainly this is a new issue for me.

I am using PE micro multilink universal, SWD/JTAG configurations, IDE Code Warrior.


I have:

Reset_b: 10K pull up

Ez_port: 10K pull up

DIO: 10K pull up

CLK: 10K pull down + capacitor 1000pF pull down


I followed above circuit recommendations from other posts and datasheets from freescale.


I attach some print screens of my process:




I am really  concerned about this, cause I can't explain how it's possible that I have succes with 2 chips (both configurations SWD and JTAG) but no with  other.


I hope you can help me with this.


Thanks so much.