LPC55 cannot restart debug session

[awseiger]

Hello,

I have been developing a secured LPC55 application, and have been using the "connect to running target" option to debug the program. This all worked until a few weeks ago, and I do not know what changed.

I am using a SEGGER J-link probe, and I get the following output when the probe issues a reset the device:

SetupTarget() start
Disabling flash programming optimizations: Compare, SkipBlankDataOnProg
SetupTarget() end
Connected to target device.
ResetTarget() start
Reset strategy selected in debugger ignored. Performing device specific reset.
Reset handler addr: 0x00000180
ROM entered ISP command handling loop. Re-enable the debug access.

I cannot see any way to exit the ROM loop, short of a hardware reset of the MCU. Doing so disconnects my debug session, and therefore it is impossible for me to debug any initialization code.

Thanks,

Alex

[Alice_Yang]

Hello,

What do you mean about " a secured LPC55 application,"?

And please check whether you chip enter ISP mode.

BR

Alice

[awseiger]

Alice,

I am running the LPC55S28 with secure boot enabled, and my application is a signed binary loaded via ISP using the SB2.1 image upload procedure. 

The chip is not in ISP mode, as I cannot get it to respond to blhost. The ISP pin is not being held low either, so it should not be entering ISP mode upon reset.

Alex

[Alice_Yang]

Hello awseiger,

Does the original project can work well after reset  your board? Or program a new secured image through BLHOST? After secure boot, if changed some code by mistake, it can't connect to debug.

[awseiger]

Alice,

The program runs just fine - I can load a new one via BLHOST and debug with no issue.

The problem occurs when the debugger issues a device reset, as this causes the MCU to lock up. The only way to resolve the lockup is to issue a reset via the nRESET pin or power cycle.

I am having this problem with every LPC55S28 board I have (even the EVK boards).

I tried disabling secure boot in the CMPAon one of my boards, and now the MCU does not run the application, and cannot connect to a debugger. I have made a thread (linked below) following this secondary issue caused while trying to solve this issue:
https://community.nxp.com/t5/LPC-Microcontrollers/LPC55S28-cannot-connect-debugger-or-enter-ISP-mode...

[Alice_Yang]

Hello awseiger,

It seems ARROW helps you create ticket to salesforce  about your this issue, I have reply on that case,

if need we can cc to you.

BR

Alice