##### The CPU freq = 400 MHZ ####
estimate memory size =64 Mbytes
GPIO Init:
UARTF_SHARE_MODE:GPIO
GPIO_MODE_REG status:0x40039c
Please choose the operation:
1: Load system code to SDRAM via TFTP.
2: Load system code then write to Flash via TFTP.
3: Boot system code via Flash (default).
4: Entr boot command line interface.
7: Load Boot Loader code then write to Flash via Serial.
9: Load Boot Loader code then write to Flash via TFTP.