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Tracing JTAG pinout - DIR685 storage router

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samurai_ttl

Beginner

Posts: 16

1

Saturday, January 14th 2012, 2:49am

Tracing JTAG pinout - DIR685 storage router

I've a board with SL3516 and Spansion flash. The JTAG numbering is a bit different than the standard 20pin ARM pinout like 1-20, 2-19...

I thought maybe the numbering is wrong and used ULink2 to check if I can get JTAG working but it won't work.

Does anyone know if there is a way to trace out the JTAG pinout?

Any help is appreciated in this regard.

Thanks

HWguru

NAS2000-Team

Posts: 1,039

Location: Wien

2

Sunday, January 15th 2012, 2:13pm

Hi,
first of all I would like to know what equipment and knowledge about hardware you have.

Do you own a multimeter and know how to measure voltages and resistance?
Which JTAG cable do you have?
Did you try our flashtool? I think it is good for finding the correct JTAG pins.

First you should check which pins are GND and VCC.

Then we measure the voltage on all other pins.
Normally TCK, TMS, TDI have a pullup to VCC and DBGRQ a pulldown. You should see the resistors near the connector or near the CPU.

Then we try to find output signals DBGACK and DBGRQ. You could try if a pin goes to high if you touch all of the other pins with a 100 ohm pullup.
DBGRQ is at low level. In response to DBGRQ DBGACK will turn from low to high.

The SL3516 only has implemented a JTAG debug interface but no boundary scan.
I don't know if the Keil ulink2 will support the Cortina CPU.

Our flashtool only supports an LPT wiggler based or FTDI FT232R USB adapter. From another thread I guess you own such an adapter which may be used for this.
In the verbose mode you get some important information for checking what is happening on the pins. If 0ffff is read TDO sticks at high and if you get 0 it is at low level.
For reading the JTAG ID TDI is not required. TCK, TMS, TDO is sufficient.

Some boards like this one don't have a JTAG connector.

HWguru
Leute ohne Laster haben oft wenige Tugenden...
NAS2000 2.3.2.IB.2.RS.1+Lüfterabschaltung+SSH+do_it+zusätzliche commandline tools+changed root password
1. suchen - lesen - Google - lesen - 1. Fragen gehören ins Forum, dann profitieren alle davon!

samurai_ttl

Beginner

Posts: 16

3

Sunday, January 15th 2012, 8:16pm

Hi there,

I've a DIR 685 router, a DMM and using Ulink2 adapter http://www.keil.com/ulink2/

I don't know if the flashtool would work and hasn't been tried. I will have to read about it on here.

Thanks

This post has been edited 1 times, last edit by "samurai_ttl" (Jan 15th 2012, 9:53pm)

samurai_ttl

Beginner

Posts: 16

4

Wednesday, April 17th 2013, 4:18am

So I''m back on this task.

I got this FT232-TTL USB adapter with jumper cables connected to the JTAG header. Before that I measured the voltages on each pin.

Pins 1, 2, 3,5,7,9,19 are at 3V and rest at 0v.

I've TDO & TDI and DBGRQ & VCC shorted. Running the flashtool I get this -

Source code

 
1
2
3
4
5
6
7
8
9
10
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13
14

Testing cabletype 3
JTAG-IDCODE: 0xffffffff  - not OK
Expected: 0x00526fa1
Bypass-test: 0xffffffff  - not OK
Expected: 0xaaab5554

Testing cabletype 4
JTAG-IDCODE: 0x00000000  - not OK
Expected: 0x00526fa1
Bypass-test: 0x5555aaaa  - not OK
Expected: 0xaaab5554
Cable type 4 detected.

Short plug detected.


Now I'm not sure what's wrong. The USB cable is about 1m long. Hope that's not a problem. Any suggestions to get the JTAG working?

Many thanks!

HWguru

NAS2000-Team

Posts: 1,039

Location: Wien

5

Wednesday, April 17th 2013, 8:47am

Hi,
you have to connect TMS and TCK as well. Have you done that?

The JTAG bypass Test seems to return "0x5555aaaa" on TDO which is the same pattern as sent by the tool.
The length of the USB cable is not critical. For me it looks like your JTAG connection is incorrect.

You get "Short plug detected" when the pattern sent on TDO is received on TDI without the 1 bit delay (0xaaab5554) you normally see on a JTAG interface working correctly.

HWguru
Leute ohne Laster haben oft wenige Tugenden...
NAS2000 2.3.2.IB.2.RS.1+Lüfterabschaltung+SSH+do_it+zusätzliche commandline tools+changed root password
1. suchen - lesen - Google - lesen - 1. Fragen gehören ins Forum, dann profitieren alle davon!

samurai_ttl

Beginner

Posts: 16

6

Wednesday, April 17th 2013, 5:34pm

Yes TMS and TCK are connected. I followed the pinout ( cable type 4 ) given at
http://forum.nas-forum.org/index.php?pag…04791c498e5d29c

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