My K81 project firmware communicates to a PC-hosted application via LPUART2 through an FTDI USB-to-Serial_TTL cable.
If I run in debug - i.e. Segger J-Link attached and under control of MCUXpresso's debug environment - with or without the serial cable attached, then everything works.
If I reset the K81 board with the serial cable DETACHED, then everything works. If I attach the serial cable while the board is running, then everything continues to work.
But... ...If I reset the K81 board with the serial cable ATTACHED, the K81 is usually unresponsive, but occasionally works.
Note: No semi-hosting (using libcr_nohost_nf.a)
Any ideas on how to track and solve this problem?