TS-7250-V3 U-Boot shell

From embeddedTS Manuals

The U-Boot shell is a powerful tool. It allows for modification of the environment, and the ability to run commands directly. By default, there is only one way to enter the shell: Pressing the "Esc" key twice followed by a 1-second window, this will bring you to a shell prompt provided by U-Boot. If pressing the Esc key twice is found incoming on the serial terminal within this time window, then U-Boot will drop to its shell. This behavior can be modified by setting the U-Boot environment variable bootdelay. This variable if modified will force the timeout for pressing the Esc key to be however many seconds the variable is set to. If it is set to 0, then the Esc prompt is skipped.

Note: Use caution when setting "bootdelay", a value of 0 means it is no longer possible to enter the U-Boot shell. We do not recommend utilizing "bootdelay" in this manner, as we do not support it. Be sure to read the U-Boot Documentation for further details U-Boot Documentation