Hi
every mikrotik device has onboard TTL interface (TX,RX,GND,3.3V pins) but it does not work
i need to use it as RS232 console port
how could i enable it ? (maybe some hardware or software hacks)
Sadly it's disabled in ROS and there is no BIOS you can access like on old RB4xx boards.
But this is just software limitation of ROS and restriction MIkrotik choose to make to their own software.
If you install OpenWRT, UART pins can be used like any other serial port for console access and to see kernel booting.
On the models that have the serial port available on the outside (as DB-9 or RJ-45) it still works, so it is a bit strange that it does not work on models that have only the TTL signals...