How to stop u-boot autoboot?

acckiitvar

Hello, I'm using AIO-3568J board and can't load into U-Boot console.
I connent USB-UART https://www.waveshare.com/ft232-usb-uart-board-type-a.htm to debug serial port https://wiki.t-firefly.com/en/Core-3568J/debug.html. I see bootlog via minicom on 1500000 8N1 without flow control but can't send anything to board. Also both LEDS on UART-USB is blinking (TX and RX).

I have done some research and what I get:
1. Default u-boot has 0 boot delay, so I create my own u-boot with SDK and it has 15 seconds boot delay and I flashes it to my board.
2. Pressing Ctrl+C doesn't do nothing, as any other buttons. I added some prints to U-Boot code and figure out that board doens't got any buttons presses.
NS16550 driver reads LSR.DR bit and it is always 0.  Also RHR (RBR) register is always 0.  I checked connection AIO-3568J <> USB-UART several times. Use 2 different AIO-3568J boards and 3 USB-UARTs.
What I do wrong? I think I have very simple problem, but I can't found solution.

acckiitvar

I found answer.
On https://wiki.t-firefly.com/en/Core-3568J/debug.html page there is an error:
On picture debug pins are in order (from left to right) RX->TX->GND, but proper is GND -> TX -> RX. It is printed on the back of the board.