I have nrf52840 on my custom board (Based on IMX6, Running Yocto linux) which is connected over UART.
I want to do an OTA of zephyr OS on that chip over serial/ble and for that i had already tried following things.
1) I have build smp_svr and flashed it to nrf52840 so that i can use 'mcumgr' command line tool for the flashing.
Referred https://docs.zephyrproject.org/1.14.0/samples/subsys/mgmt/mcumgr/smp_svr/README.html?highlight=build%20smp_svr to know how to use 'mcumgr'.
Now, when i use mcumgr to communicate 'hello' message over serial/UART, It shows error of connection timed out. (Also tried with -t switch, but no luck).
Command used are :
sudo mcumgr --conntype serial --connstring='dev=/dev/ttymxc0,baud=115200' echo hello
--> So it's not able to open the connection using mcumgr and not getting any reply (Getting timeout).