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How dead is dead? No response from bus pirate jtag(s).

Posted by Paul Krupa 
I have a dockstar that I unsuccessfully flashed with an image over a year ago. No blinking light. I plugged my serial port in and no response. I got a Bus Pirate and Openocd and tried to connect but the output appears to mimic that of a disconnected jtag. I've re-checked connections but the dockstar fails to give any sign of life on the terminal or the jtag.

The chips get hot. The voltage from the power supply is at 12 volts.

I bought another bus pirate because I found that the unit failed the self test. I noticed two pins had been oversoldered (I tried to fix that but the my solder sklls and tools failed).

I tried numerous firmwares on the bus pirate since there was some confusion over which firmware actually still had the jtag stuff in it. I think I have a good firmware since it spits out the output of a disconnected jtag in openocd.

I am thinking of getting a TOA jtag.

Any ideas?

Re: How dead is dead? No response from bus pirate jtag(s).
July 30, 2013 07:06AM
Hi Paul,

I apologize if this is a bit off topic. Is this C20A I2C SPI UART Bus Pirate Bus Simulator the Bus Pirate you were talking about?
That looks like a bootleg version. It's an open source design so I expect it would function. The solder on the IC looks a little fat but I should talk. My BP from Seeed Studio had two pins soldered together on one IC.

There is a lot of stuff from several sites describing using the BP to unbrick the Dockstar but the information varies. For example, one guy is using pull down resistors on his rig. I am going to try that next.

I got an NSA320 off ebay for 53 bucks so I am distracted at the moment. I am hoping I won't have to use my failed jtag experiences on the zyxel!

Why do you ask?
Re: How dead is dead? No response from bus pirate jtag(s).
August 01, 2013 08:02AM
Just curious about BP mainly because I never heard of it and now am thinking to get one.

As with de-bricking a Seagate Dockstar, I am contemplating to get this J-link Jlink V8 ARM Emulator, but I have no idea if this can be used as a JTAG cable. What do you think?

Paul Krupa Wrote:
> Why do you ask?
Hi Paul,

I've managed to land myself in a similar situation. I've been using a Buspirate from Sparkfun and a Ft232rl serial connector to my dockstar.

Initiall my problem was that the dockstar was in an infinite reboot loop, which I managed to interrupt with help from the ft232rl serial connection. I also was able to install a new uboot & debian on a usb. After some stupid (my stupid) nand scrubbing I ended up where I am now.

The symptoms of the dockstar are the same as yours. I feel the chip getting hot but get no lights, no response on the serial connection, the Buspirate outputs seem to indicate no communication with the dockstar either.

I've been following this guide: http://plume.redox.ws/article13/dockstar-debricking-jtag-with-buspirate

Have you tried it/had any success reviving your dockstar with another approach?

Re: How dead is dead? No response from bus pirate jtag(s).
August 28, 2013 07:30AM
I ordered a taio parport wiggler and had success with that. It was problematic but to make a long story short it was all my fault. I did learn a lot and I am presently trying to get Davygravy's macplug running the way I want it on my recovered dockstar.



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