In message 436eca11.0ec11203.0cfa.ffffcb34@mx.gmail.com you wrote:
After implementing support for USB-based console ("setenv stdout usbtty; setenv stdin usbtty") through serial port, I want to download kernel to flash through USB port. So I connected USB port and typed the command loadb
"loadb" uses Kermit binary protocol. I am not sure if hyperterminal can send data using this protocol.
using the terminal named Hyperterminal in Windows. But I found that the kernel had been downloaded to flash through serial port rather than USB
No. If you have usbtty working, than your USB link works exactly like a serial port as far as U-Boot is concerned.
port. If I cut down the connection between host serial port and target serial port, I can not type any command. How can I deal with this problem.
U-Boot is waiting for a file download using Kermit Binary Protocol. Either you send a file using this protocol (which requires a tool that implements this protocol - as mentioned before I recomenmd to use kermit), or you can terminate the download by pressing ^C.
Best regards,
Wolfgang Denk