Disabling JTAG on MP5567

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Disabling JTAG on MP5567

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AROK
Contributor I

Hello

 

 

I'm trying to disable the JTAG on MPC5567.

I've tried to erase the shadow flash : The MCU no longer boot from internal flash ( Bootcfg = 0 0 )

Changing the shadow flash y JTAG doesn't work well ( get several part bricked trying to change the shadow flash with a Cyclone tool)

 

Question :

1) Reading the 55667RM doesn't explain why MCU doesn't start when the shadow flash has been erased ( it does on 5644A)

2) What shall really be changed to secure the MCU ? ( block the JTAG to avoid a reading of the internal flash)

 

Regards

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AROK
Contributor I

Tnkas

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davidtosenovjan
NXP TechSupport
NXP TechSupport

If MCU is censored, it behaves according following table:

SIU_RSR(BOOTCFG[0:1]) , boot mode, internal flash state, nexus state

00, internal boot, enabled, disabled

01, serial boot, disabled, enabled

10, external boot, disabled, enabled

11, external boot, disabled, enabled

I don’t see any reason why fully erased shadow flash should block booting from internal flash, I would rather guess you have changed something else. I would recommend to only modify serial passcode and control word with private password in order not to permanently lock the device.

Pay attention to following appnote:

http://cache.nxp.com/files/32bit/doc/app_note/AN3787.pdf

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