NRF52820 firmware stuck waiting for RTT

[mscottwvc]

I'm not sure if this is expected behavior, but when using NRF82820 with printf or printk with the device setup to log to RTT the firmware hangs for 30+ seconds unless RTT is started. This doesnt happen with the NRF5340 (very different chip but thought worth mentioning). I have tried lots of different KCONFIGs, but nothing seemed to help. If I step through with the debugger then the program faults on the print line, without the debugger it just hangs for 30+ seconds (assuming RTT is not connected) and then seems to work fine.

So am I doing something wrong or this is expected behavior? Is there a workaround?

my latest Kconfig experiment was the following (using printk only):

CONFIG_LOG=y
CONFIG_CONSOLE=y
CONFIG_RTT_CONSOLE=y
CONFIG_USE_SEGGER_RTT=y
CONFIG_UART_CONSOLE=n
CONFIG_LOG_BACKEND_RTT_MODE_BLOCK=n
CONFIG_SEGGER_RTT_MODE_NO_BLOCK_SKIP=y
CONFIG_LOG_PRINTK=y