This tutorial is designed specifically for tjtag-v3.  Other JTAG versions may require a different instruction set.  Once your JTAG cable is ready (click here for instructions on building a JTAG cable) and the Vcc of serial has been connected with the Vcc of the JTAG header, we need to perform the following steps.

Initial Steps To Set Up A JTAG Connection

1.  Connect the DB25 plug with the parallel port of your PC, and other end of the cable with the JTAG header on the board.

2.  Execute "rmmod lp" to free the parallel port.

3.  Next, power on the board and give the desired JTAG command on your PC.

Purposes of the JTAG Commands

JTAG commands in tjtag -v3 generally serve three purposes:

1.  To keep a backup of the contents of the router's flash memory.

For example, to backup the CFE, one would run the following command:

./tjtagv3 -backup:cfe

2.  Alternatively, to erase the CFE.  In order to do this, you would run the following command:

./tjtagv3 -erase:cfe

3.  Finally, you can use JTAG to flash a fresh CFE, using the following command:

./tjtagv3 -flash:cfe

Syntax of the JTAG Command

The syntax of the JTAG command is as follows:

tjtagv3 [parameter] /bypass /st5

Here, the parameter indicates the commands to be given.  The values within <> indicate different options that are available to you.

Please note that if "flashing," the source filename must exist as follows:  CFE.BIN, NVRAM.BIN, KERNEL.BIN, WHOLEFLASH.BIN or CUSTOM.BIN BSP.BIN.

Please head on to the next page for a summary of available commands and paramaters for JTAG.

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