Reading CREG locks up LPC4357

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Reading CREG locks up LPC4357

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Contributor I

I'm using LPC4357 with Keil, and when I view the contents of CREG (in either the memory viewer or the system viewer) the MCU locks up and I get the error "Could not halt Cortex-M device". It seems to be most sensitive to views in the USB0FLADJ  and USB1FLADJ regions, because I can view lower regions of CREG with the IDE only complaining about not being able to access some these memory locations. I can't tell if it's going off into the weeds, or actually locks up, but the LED's stop flashing for a Blinky example, and requires a power cycle to be able to connect to the LPC again. 

We are investigating the Keil side.  Is there anything on the NXP side that would cause this behavior? 

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3 Replies

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Contributor I

Thanks, Bernhard!

Any clue as to why Keil is unable to read CREG addresses below the FLADJ registers?

Best regards,
Cameron P. LaFollette

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NXP TechSupport
NXP TechSupport

Hi Cameron,

What's the means of "why Keil is unable to read CREG addresses below the FLADJ registers?"

I could read the CREG registers info from system view window:

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Have a great day,
Mike

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NXP Employee
NXP Employee

The information in the LPC43xx User's Manual implies, that this issue is based on the chip specific implementation:

Remark: The FLADJ register must be read only after initializing the USB interface.
Reading this register before initialization of the USB causes the MCU to stall.

So I would say that it is not an issue with KEIL µVision.

Regards,

Bernhard.

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