Thanks for the quick answer. Is it the Pin CH6 for softserial?
I’m using iNav, I’ve seen the target is OMNIBUSF4V3 for the F4 Omnibus V5.1 board. But unable to activate softserial (Enable CPU Based serial port) with this Target. I have a message like "Unrevcoverable failure of serial connection, disconnecting…failed to close serial port…"and it doesn’t reboot automatically. Is F4V5.1 not supported by iNav?