1x 74HC245N IC Octal Bus Transceiver
1x LM317T Voltage Regulator
2x 100nF conductor
1x 220Ohm resistor
1x 5kOhm resistor regulable
1x PC powercable
1x IDE connector
1x parallel printercable
6x bouncing pins which fits into an IDE connector
4x hours of patience
1x extra couple of hands

The beginning

First we start with demolish!!! Demolish a parallel printercable, the first you can get.

Open the connector and desolder the wires.

Diagram Octal Bus Receiver:

We build the JTAG interface as shown with the chip 74HC245. Instead of using the 74LS245 (TTL) better use the 74HC245 (CMOS), it can handle the 3.3Voltage better.



We solder the IC directly to the parallel printerconnector:

74HC245 Parallel connector

pin 11 - pin2
pin 12 - pin3
pin 13 - pin4
pin 14 - pin5
pin 15 to the JTAG pin 1

As you did this, make a groundwire over pin 1,10,16,17,18,19 from the IC, this will be our common Ground, from this wire make a connection to pin 25 from the parallel connector. 

Soldering:

Now we start to solder the IC to the parallel connector.

Solder pin 5 from the IC to pin 11 from the parallel connector. Now we finished soldering at the parallel connector.




Diagram Powersupply:

Use this diagrom to build the Voltage Regulator
This voltage regulator is build with an LM317T Voltage Regulator, and some conductors and resistors.



The IC needs a voltage from 3.3Volt at pin 20 from the IC, we use the voltage from the harddisk powersupplyconnector of your Dreambox.
This is 5Volt and must be addepted by the voltage regulator.
We place the regulator, conductors and the resistors in the housing of the parallel cable.

Place the regulable resistor on a way that you allways can adjust it.
Therefore we make a little hole in the housing and we glue the regulators into the housing.

Detail of the regulable resistor.



As we finish this, we start with our connections of the cables.
What do we need?

We have 6 wires to the Jtag connector on the mainframe of the Dreambox, 2 wires for the powersupply of the harddisk connector, so 8 wires in totall.

We pick some nice colors and start with soldering. We start with the soldering og the powercables. The other are for the harddisk connector and the JTAG pins.

PAY ATTENTION: The 5 volt voltage comes from the red wire, the black one is the Ground.

We start with adjusting the voltage. With a voltagemeter we adjust the voltage untill it's 3.325volt. We have the best resultage with this value.

The ground of our voltage is connected to the common ground of the IC , the poweroutput is connected to pin 20.

Aaahhhh, we are almost there!

Now we need to connect pin 6.7.8.9,10,15 from the IC to the wires from our connector.



And voila this side now is ready. We need to position everything into the housing, you'll get something like this:





As built parallel connector.



Our hobbybox :)



Now we start with the Dreambox connector part.



We solder the bouncing pins to the wires.

Pin 15 from the IC to pin 1 of the JTAG connector
Pin 6 from the IC to pin 3 of the JTAG connector
Pin 7 from the IC to pin 7 of the JTAG connector
Pin 8 from the IC to pin 9 of the JTAG connector
Pin 9 from the IC to pin 11 of the JTAG connector
Pin 10 from the IC to pin 16 of the JTAG connector

If you look good, you can see that we demolished an IDE connector from a harddisk, took the cable off the connector and the pins out of it.
We drilled the holes of the pins a bit larger so the bouncing pins could stuck in tight.

This connector has the same pindistance as the connector on the motherboard. That's why it is a very good positioner!



Via the Satnerds Dreambox Board another solution from Netforce came to us!

"Hi everybody,
To build the JTAG interface we need the bouncing pins, but these are hard to get.

I (Netforce) found an alternative way to buils the connector. I made it from an old 5 1/4" floppy cable connector and a piece off experimental print.

Demolish the little pins from the connector ans solder the to the experimental print.

Tape the original connectorhouse to the print so you can hold it easialy."

Building the JTAG connector.





This is the final result of our JTAG solution.



Together with the elektronicaparts



Now our Jtag is ready we can go further with the software part. Flashing the software is done with the Linux operating system. If you don't have linux installed, uou cab use Knoppix.

Knoppix is a BootCD with Linux on it.

This way you don't have to install it, just put the CD in your CDRom-speler and boot your PC.

You can download it from Knoppix and burn it to CD.

Start Knoppix, and acces the Desktop, in your taskbar you see a symbol as a seechell, this it the socalles Shell.

We need this one, activate it and a sort of DOS screens opens.

PAY ATTENTION: Don't use extensions behind the JTAG-files, otherwise they don't work! You need to remove the .dat extension, leave the .bin untouched!

PAY ATTENTION: Knoppix automaticly logs in as the user "knoppix".

We give the command:

su

This means that we want to login as "Super User"

We also need the JTAG software, you can download it at our downloadsection.

We copy this on a diskette and we "mount" it by the command:

/mnt/floppy

With this command we say that we want to use the floppy.
And we go to the directory "dir" at the floppy with the command

cd /mnt/floppy

From this directory we give our flash commands!

Now position the JTAG on the mainbord of the Dreambox, plug the powercable, and then you put the Dreambox on.

Where do we find the JTAG connection on the mainbord?

A: The heart ot the Dreambox, the IBM STB04500 CPU
B: EEPROM, 28F640J3 (8 Mbyte)
C: RAM, 4x 48LC8M16A2 (4x 16 Mbyte = 64 Mb total)
D: Ethernet chip, SMSC LAN91C111-NE
E: Video encoder chip, STV6411A
F: Frontend chip, ATMEGA8 16AC

The JTAG connection:

OK, now we are ready to start and we give the command:

./flash unprotect

We see some information on the screen, we must see 4x zero and after that reseting ok:

cpu seems to be ok
. 0
. 0
. 0
. 0

Give the command:

./flash write

If everything is ok, it started to Flash, you can notice it by the counter.

PAY ATTENTION: keep the connector still during flashing, DON'T PUSH TO HARD.

When you see te announcement OK and reset, shut of the power, disconnect everything and flash as usual with the serial link.

When you report faults during 1 of the 2 procedures or have no connection anymore, the connector or your voltage-output is not OK.

Have fun and good luck, if you have questions about the JTAG or other hardware question about the Dreambox, you can ask them on the Satnerds Dreambox Board!

This software comes from our German colleagues. Build and tested it fully together with Compy.

Thanks Compy :)