MCUxpresso LPC804 redlib nohost uart0 will not run without debugger attached

[stevenriedl]

Looked over all of the posts and documentation. Seems to be something with semihost, but not using that and have semihost hard fault handler. Thought it might be watchdog configured, but insured that was disabled. Using a release build that uses 56% of flash, debug was over 100%.

Everything runs great with debugger attached, but nothing with it not. LED on GPIO port never initialized by pins, faintly on when not initialized.

Linkserver debugger 

SDK_DEBUGCONSOLE=0

Very little hair left at this time.....

[stevenriedl · Accepted solution]

I think I found the reset issue, nice AN on the topic... Wish it was easier to find...

https://www.nxp.com/docs/en/application-note/AN12724.pdf

[stevenriedl]

Tried to attach to running target, but it wasn't running. There seems to be a problem with the power on reset. This board is an I2C target and provides power to the I2C master, If I unplug and plug the I2C master (QIIC connector) the chip starts up, sometimes after just waiting 30 seconds to a minute it just starts up. Have a scope trace below (yellow +5 supply, Green 3.3V regulated supply and blue is reset input. The 5V does run 2 relays through a relay driver IC, was concerned they were feeding voltage back in before the 3.3 V came up, but that is not the case. May try adding an external RC to delay the external reset.

[ErichStyger]

Hi @stevenriedl ,

have you tried to attach to the running target to see where it is hanging?

I wrote an article about this here:

https://mcuoneclipse.com/2021/04/25/attach-with-the-debugger-to-a-running-target/

I hope this helps,

Erich