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JTAG DRX 890-C (Read 43077 times)

Matt52656
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Re: JTAG DRX 890-C
Reply #15 - Jan 13^th, 2017, 1:59pm

This is in response to the message on the other thread.....

Quote from delboy1234 on Jan 13^th, 2017, 12:34am:

That's some impressive work. Did that give you full access to the board over an i2c connection? How did you go about tracing pintouts on the board for something like that.

The new HD boxes (DRX890) also use a similar MIPS32 processor in the form of BCM7335
I have got a pinout for the BCM7335 that shows EJTAG and BBS pinouts but as your already aware they don't seem to be active.
BCM7335_EJTAG.zip (attachment)

AAAHHHH you have a diagram which shows you some pin numbers, that should be really useful. Did you find the pins on the board ???
I "guess" it would be best to hold the RESETb line down while you power up the board, so its more lightly that the ejtag would be accessable using something like UrJTAG (or whatever you use) ?.

IMHO I would give-up on the I2C/BBS connection because I think Sky would never allow this.

About finding the board pinouts (on a Thomson box not the Amstrad).....
All those connections were direct pins to the flash. I see that sky uses dual flash's for backup so I removed one of them to see the pins.
* Unfortunately I removed the primary and not the backup, which caused power on issues. So I had to bodge the CE lines *
The thing that helped me map out the pins was aluminum foil... I had one of the multimeter probes on a flash pin, then I rubbed the probe (with the foil) over the board until I heard the annoying buzz from the multimeter.

Another thing I did for completely different small BGA chip, was to cut a very thin strip of foil and slide it under the chip. So I could find the outside pins 'quite' easily. But the inner pins were a pain.

Heres some old pictures, because I'm guessing you are curious.

2015-Thomson-Sky-DSI8215.zip (517 downloads)

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delboy1234
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Posts: 13

Re: JTAG DRX 890-C
Reply #16 - Jan 19^th, 2017, 10:37pm

Unfortunately not. I connected the jtag to the board in what I thought was the correct area but didn't get anyting back from urjtag.
I could of messed up the pull up resistor values, got the wrong connection for the RESETb line or just damaged the board when soldering.

Picked up a new DRX890 today so hope to have another try over the weekend.
Either was its good to see some activity in this and the other thread again!

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johnjoes58
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Re: JTAG DRX 890-C
Reply #17 - Apr 28^th, 2017, 10:06am

Quote from delboy1234 on Sep 29^th, 2014, 2:42pm:

Unfortunately still not having look with JTAG/i2c. The msi file is the correct one for BBS so that isn't the problem. I managed to find somewhat of a chip diagram (_http://www.2shared.com/document/nkt6a6wF/BCM7335_EJTAG.html).
After looking at this it took me to somewhere else on the board for the i2c port but still the same result. When the cypress board is connected the box fails to boot properly but nothing past that.

I still think its possible to connect to the box but i'm wondering if the chip is somewhat 'password protected' What I mean by that is you would need to use a key sequence or command to connect. Again no luck with this either so far.

If anyone has any other ideas on this let me know what you think

Has anyone got a working link for the drx890 chip?

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romman
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Re: JTAG DRX 890-C
Reply #18 - Dec 18^th, 2018, 2:48am

Has anyone had a look at this

http://www.ph-mb.com/products/sky-fw-tool

Just wondering if the firmware could be modified for recording purposes like the old pvr2, i suppose whats key with later skyboxes is the sky modified linux firmware and its security checks prohibiting access via jtags.

Does anyone know if any of these later model sky boxes have bga chips in use?

Cheers

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