Dpc 3825 bricked?

This forum discuss about how to JTAG different devices.
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cheeto
Junior Member
Posts: 93
Joined: Fri Aug 01, 2008 6:14 pm

Dpc 3825 bricked?

Post by cheeto »

Hey guys,
I have a dpc 3825. Before anything, I do have a backup of the original firmware as well as firmware from another dpc 3825.

I'm able to connect to the 3825.
Every time i press the ID button on the USBJTAG softwarei get this message:
-flshdct 0
Found Address= 00000000 25FL064A

Here comes the problem....
For some unknown reason I can´t WRITE with the usbjtag nt.
I can´t even erase.... it appears it's erasing but it doesn´t
When i write an image or a config file etc..., and i press VERIFY, I get some errors like this:

Compare data Failed address 0,target 00,PC memory 0B


The modem seems to be bricked but i'm able to detect it....
Any ideas on how to debrick, or better yet can someone tell me why the usbjtag nt isn´t able to write or erase??

thanks folks!!
usbbdm
Junior Member
Posts: 8962
Joined: Mon Jul 18, 2005 9:33 pm

Post by usbbdm »

Do you connect it directly?
To be able to erase it, the chip needs to have WP pin high as well as HOLD pin high.
Also you need to have enough power to the chip.
Being able to detect the flash has much lower requirement for the power voltage and no limit on WP or HOLD.

You need to rule out other issues to be able to program the chip.
cheeto
Junior Member
Posts: 93
Joined: Fri Aug 01, 2008 6:14 pm

Post by cheeto »

Hi and thanks for getting back to me.

I'm no expert at this, but I've flashed this modem before using the same method as now.
How do I set the Write Protect to HIGH? Does this mean that I must give it 3.3v? So that would be PIN 1 AND 9 on the flash chip?


Anyway this how I've have it connected:

JTAG -----> flash

Pin 4(GND) ISP -----> U110
Pin 3(TDI) -----> Pin 15(SI)
Pin 5(TDO) -----> Pin 8(SO)
Pin 9(TCK) -----> Pin 16(SCK)
Pin 11(RESET) -----> Pin 7 (CS)
Pin 2(GND)-----> Pin 10(GND)

Here is a video of what is happening:

https://mega.nz/#!aYUTnSbL!lB5iaOAlfsme ... Ba6h_mpu-A


here is the verify error I'm getting:

https://mega.nz/#!CdUn1TBZ!bjOISH0lk9B1 ... -QORfLJMA4

Any suggestions?

Thanks again!

btw, I also tried 3.3v connection but that won't detect at all. :(
usbbdm
Junior Member
Posts: 8962
Joined: Mon Jul 18, 2005 9:33 pm

Post by usbbdm »

Use a multi meter to measure the WP pin and HOLD pin to see if they are high (3.3v).
cheeto
Junior Member
Posts: 93
Joined: Fri Aug 01, 2008 6:14 pm

Post by cheeto »

Ok, I tested pin 1 and 9 on the flash without my usbjtag connected, in other words i connected the tester directly on the chip

Both pin 1 and 9 gave me a reading of 3.23


BUT when i have the usbjtag connected the the flash i get a reading of ¨0¨.

I must confess that when i first flashed the chip i forgot to ground it. (jtag pin 2 ---------> flash pin 10)

It actually did connect to the chip but when writing it took forever. at least 45 min!

Perhaps i screwed up the modem? or maybe the usbjtag? or both?

Thanks for your help.
usbbdm
Junior Member
Posts: 8962
Joined: Mon Jul 18, 2005 9:33 pm

Post by usbbdm »

Without connect GND pin, you will not get proper result.
When connect two device together there is always a risk of damage one side or both. However with basic precaution, these can be eliminated.
1. When connect pins try to avoid either side is powered on. Hot plug is a receipt of killing device.
2. In winter, we normally carry static charge, so touch ground (like computer case) before touch any component.

Try to read another chip and if you can then your JTAG is still fine, I cannot say that for your modem though.
cheeto
Junior Member
Posts: 93
Joined: Fri Aug 01, 2008 6:14 pm

Post by cheeto »

Again, thanks for getting back to me.
I took your advice and successfully cloned a Docsis 3.0 with 3.3v on pin 2 without any issues. So I guess my USBJTAG IS FINE. :)

As for the modem, i guess it's dead.... the strange thing is that it's easily detectable with the jtag... but i guess i must have messed it up when flashing without a ground on pin 10 of the flash.

LESSON LEARNED. :)
Thanks again!!
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