Dangerous Prototypes

Dangerous Prototypes => Bus Pirate Support => OpenOCD JTAG => Topic started by: bootsector on October 09, 2011, 03:05:10 pm

Title: Using a Bus Pirate v3 to unbrick an HTC Magic
Post by: bootsector on October 09, 2011, 03:05:10 pm
Hi guys,

I'm wondering if I will be able to use my BP in order to unbrick my HTC Magic via JTAG as shown here:

wiki<dot>cyanogenmod<dot>com<slash>wiki<slash>HTC_Dream_%26_Magic:_JTAG

There are two main things that I'm not sure if BP supports:

1 - Does it support a 2.6v voltage reference? This is required by the phone.

2 - ARM JTAG uses a "TRST-N" pin. Does BP support it? Where should I connect it in the BP? This pin must be 2.6v

Thanks in advance!
Title: Re: Using a Bus Pirate v3 to unbrick an HTC Magic
Post by: robots on October 09, 2011, 07:18:03 pm
[quote author="bootsector"]Hi guys,

I'm wondering if I will be able to use my BP in order to unbrick my HTC Magic via JTAG as shown here:

wiki<dot>cyanogenmod<dot>com<slash>wiki<slash>HTC_Dream_%26_Magic:_JTAG

There are two main things that I'm not sure if BP supports:

1 - Does it support a 2.6v voltage reference? This is required by the phone.

2 - ARM JTAG uses a "TRST-N" pin. Does BP support it? Where should I connect it in the BP? This pin must be 2.6v

Thanks in advance![/quote]

No BP is only 3.6volt. You could use open-drain outputs with external pullups. TRST plugs into PGC or PGD pin, i am not sure  now :-)
Most arm processors don't need TRST pin at all, trst can be triggered using JTAG command.
Title: Re: Using a Bus Pirate v3 to unbrick an HTC Magic
Post by: bootsector on October 09, 2011, 07:26:56 pm
Thanks, robots!

Now I'm reading about Bus Blaster v2 and it seems more suitable for that purpose (it supports 2.6v, it's faster, etc...), what do you think?

If there's a slightly chance this is going to work, I will get one from seeedstudio to give it a try! :)

Thanks!
Title: Re: Using a Bus Pirate v3 to unbrick an HTC Magic
Post by: robots on October 09, 2011, 08:34:51 pm
Bus blaster should work down to 1.8volts so it should be ok. And of course busblaster is jtag, the true kind - with speed that cannot be compared to buspirate :)  (500khz vs 30mhz).
Title: Re: Using a Bus Pirate v3 to unbrick an HTC Magic
Post by: bootsector on October 09, 2011, 10:08:18 pm
Cool! :)

I've ordered my Bus Blaster from seeedstudio. Let's see how it goes... ;)

Thanks for the inputs, robots!
Title: Re: Using a Bus Pirate v3 to unbrick an HTC Magic
Post by: robots on October 09, 2011, 11:29:40 pm
good luck :) let us all know how it went

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