Rock 3A run user bin-file

Hey
Getting Started with the Rock 3A Board
I installed on a Linux SD card as written in the wiki, but I need something different.
I want to download my bin file to SD card and run it via U-boot. How to do it? If you install Linux, it starts immediately (boot delay = 0), and if there is no OS on the sd card, then the board constantly reboots. Is it possible to exit Linux through console and return to U-boot?
I tried to turn on the debug board without an sd card, and then connect the sd card, but did not find how to do it in U-boot.
Can you help with advice or a link to a guide on how to do what I need (run user bin-file from sd-card)?

P.S.
Studied other topics and experimented

  1. formatted the sd card and wrote the bin file
  2. included the board without sd card
  3. Connected the SD card
  4. Run the following commands
    4.1. mmc list
    4.2. mmc dev 1
    4.3. fatload mmc 1 50000 app.bin
    4.4. go 50000
    If I need to update the firmware, turn off the board and follow steps 2-4.
    It turns out inconvenient, but at least it works for now.
    Perhaps updating u-boot will make life easier, but I’m not confident in my abilities and would not like to influence what is already working
    I’m still looking for advice.

Power on the board, and quickly press ctrl+c, then you will get into u-boot shell and do anything you want.