(18-03-2015, 04:56 AM)yutao821 Wrote:(18-03-2015, 01:53 AM)andytg Wrote: USB JTAG
http://www.usbjtag.com/jtagnt/modem/sb5101u.php
The answer is too perfect, thank you very much
This modem does not have noisy bootloader (option "p" at boot time).
You can update the firmware only through usb jtag, soldered directly to the chip contacts, as shown in the picture
upd: if you want to upgrade the firmware only via USB-TTL -- use a cable modem Webstar (Scientific Atlanta) DPC2100R2, DPX2203, DPC2203, Thomson/RCA TCM390, DCM315 etc.. -- these models of modems have noisy boot and "p" options
upd2: USB-TTL cable -- it's not the cable for update the firmware, this cable only for connect to the console, and the firmware is updated via bootloader having the option "p"