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Why Kinetis K20 does not boot when disconnected from the debug probe?

Question asked by ADRIANO MITRE on Aug 29, 2014
Latest reply on Sep 5, 2014 by ADRIANO MITRE

I am developing an application for the part MK20FX512VLQ12 using CodeWarrior 10.6 for MCU using as debug probes both P&E USB Multilink Universal and SEGGER J-Link. Its a very simple bareboard application (i.e., no RTOS), which uses Processor Expert for all drivers. Its binary takes less than 10 KB compiled with all debugging information on and all optimization off.


I can run the application in debug mode without problems. This is without breakpoints (except at the start of "main", which is unavoidable) to help with any timing or interaction issues. When I start a debug session, hit continue at the breaking point at the start of main() and only then disconnect the debug probe, it keeps running normally (as long as NMI is disabled, at least). When I choose Run (CTRL+F11) instead of Debug (F11), however, the application does not boot.


When measuring the RESET_b pin without the debug probe connected, it oscillates like described in PK60F120M Reset pin oscillating. This is after the application has been written to flash, though. I have even verified, when debugging, that memory positions 0x0 and 0x4 are properly set. I am, therefore, out of ideas.

Why the application does not boot when disconnected from the debug probe? How can I make it do?

Any help would be greatly appreciated.