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Author Topic: What does your dreamplug do if you unplug jtag from computer?  (Read 5753 times)

sarikan

  • Newbie
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  • Posts: 15

Hi,
I've just realized that if I unplug the usb connection of jtag unit from the computer, dreamplug seems to reset itself.
I can almost remember that this is not what it used to do. I used to plug in the jtag, connect to it via putty/minicom and then when I'm done with it, unplug the usb cable from computer.
When I plug it again, it would be waiting for me to login.

Both with linux and windows, dreamplug seems to drop to boot. I fire up putty, see nothing on com6, press enter and Marvell prompt appears.

Is this normal? I mean why would the device boot if I only remove jtag from usb (leave it connected to dreamplug)?

 ???
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sfzhi

  • Jr. Member
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  • Posts: 54
Re: What does your dreamplug do if you unplug jtag from computer?
« Reply #1 on: 03 August 2011, 06:17:20 pm »

If you are using putty/minicom then you are connecting to the serial console, not to JTAG.
Do you still have the JTAG connector of the plug connected to the JTAG unit?
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sarikan

  • Newbie
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  • Posts: 15
Re: What does your dreamplug do if you unplug jtag from computer?
« Reply #2 on: 04 August 2011, 05:19:33 pm »

Ok, I'm confused now :) I have the dreamplug, and the jtag unit connected to dreamplug as shown in the user guide. The usb cable coming out of the jtag unit is connected to computer, and that usb cable is what I'm unplugging.

Maybe I've run out of brain today, but I don't understand what you mean when you say I'm not connected to jtag. The computer is physically connected to jtag via usb, and minicom/putty is talking to com6, which is the serial tty to linux (right?) so what is it that I've incorrectly expressed?

cheers
Seref
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markusd112

  • Newbie
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  • Posts: 9
Re: What does your dreamplug do if you unplug jtag from computer?
« Reply #3 on: 06 August 2011, 10:05:49 am »

Hi,

there is a differenc between JTAG and UART: the JTAG-Adapter-Box has two interfaces. An UART-Interface that a serial port with TTL (3,3V) level that is the console port of the plug. I assume, that you are using this port.

The second one is the 8 pin JTAG-port. This special interface is for testing and debugging purposes and normally not used, when you are working as admin on the dreamplug. It gives you a hardware related access to the chips on the board.

For me: it is not rebooting, when I cut the USB cable to the JTAG-adapter box.

But I have some problems with the 230V power cable: it has a slack joint, so when moving the plug a little bit, the power goes away for a short moment and it reboots... Maybe this could the cause for your problem?

Regards,

Markus
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