SB5120 Cable modem

Motorola SB5120 surfboard
The CPU of the board uses TNETC4401. The tool to debug the CPU is EJTAG (non-DMA).

Picture showing JTAG is connected
Flash One 2MB 28F160C3
Firmware 2MB $90000000-$901FFFFFF
RAM 8MB $94000000-$947FFFFF

SB5120 uses 14 pin EJTAG. It has reset pin. So a "reset" command can reset the modem. (Some modems reset might not work, a cycle power might needed. If a command needed after reset, them command should apply just after power on)

Definition in usbjtag.def Commands (usbjtag 0.09):
Name=SB5120
IRLength=5
Endian=Big
Memory=Ram,0,0x94000000,800000
Memory=Boot,1,0x90000000,0x10000
Memory=Nvram0,1,0x90010000,0xC0000
Memory=CmApp0,1,0x900D0000,0x30000
Memory=Nvram1,1,0x90100000,0xC0000
Memory=CmApp1,1,0x901C0000,0x30000
Memory=Cert,1,0x901F0000,0x8000
Memory=Cfg0,1,0x901F8000,0x2000
Memory=Evlog0,1,0x901FA000,0x2000
Memory=Evlog1,1,0x901FC000,0x4000
Programram=0x94040000
Protocol=EJTAG
DMA=No
ProbTrap=1
 Backup firmware
getram 90000000 200000
save 90000000 200000

Disable watchdog be ready to program
SB5120 has a watchdog and need to disable to do programming.
Create file named 5120p.usp
reset
detect
program
Type command 5120p
After this your SB5120 is ready to program and you can program it in normal speed without trigger watchdog.

Program whole firmware.
ldram 90000000
program 90000000 200000

You can use "reset" to restart the modem. You can not use "cmpram" command to check if the programming is ok when it says "DEBUG ON"

Rescue SB5120. When box not fire up. Normal programming will not work. First need to program boot. No watchdog exist in this case
detect
ldram boot (Select proper boot file)
erase boot
sprogram boot (Slow programming)
reset
detect
ldram image0(Any tabes you have backed up)
program image0(Any tabs you want at normal speed)

            

Lasted Updated:December 31 2016

Vists since Jan 4,2009