JTAG support?


Is there any way to use JTAG debugging with DragonBoard 410c?

There are instructions to setup a UART serial console here: https://github.com/96boards/documentation/wiki/Dragonboard-410c-Installation-Guide-for-Linux-and-Android#setting-up-the-uart-console

But that’s not a JTAG.

Apologies that my answer offered an alternative debug interface and didn’t answer your question directly. The two currently available 96Boards products, the HiKey and the DragonBoard 410c, do not offer a JTAG interface. This is an option that neither board has adopted. This is shown on page 10 of the specification: https://www.96boards.org/ce-specification.

Wow, not sure what you’re talking about steve.taylor, but BOTH boards include JTAG interface.

The 410c has JTAG on J15 (on the bottom of the board).
HiKey has JTAG on J10 (also on the bottom of the board).

Apologies again - as noted by doitright, both boards provide an unpopulated interface that is documented in the respective manuals:
On page 13 of the DragonBoard Hardware Hanual: "APQ8016 SoC JTAG interface is routed to J15. If the use of JTAG is required, J8 need to be soldered to the board. The connections and connector pitch meets the 96Boards specification for the JTAG interface."
On page 17 of the HiKey Hardware Manual: “The HiKey board includes the option for soldering a 10 pin header that brings out the SoC signals for JTAG debug. A FTSH-105-01-F-DV header can be populated at J10”

So how does it look in practice? What software and hardware do I need to have? Any change that some OpenOCD-compatible hardware would do?

I’ve seen some home-affordable development boards, that in theory supported JTAG, but in practice required specialized hardware&software, rendering JTAG useless for private developers.

Hi dpc,

I was looking at trying out the JTAG on the HiKey board, and came across some initial armv8 OpenOCD support here: -


For HiKey which had the FTSH-105-01-F-DV connector I bought the following adapter board and cable and was planning on using it with a TinCanTools FlySwatter2 (which goes down to 1.6v).


Maybe adafruit will sale a similar pitch adapter for the conversion you need.

Sadly as I’m doing this in spare time, I haven’t actually got round to soldering the connector on and trying it all out, so can’t tell you whether it works or not.

The armv8 development in OpenOCD looks quite early days, but I see no reason why it couldn’t be made to work. Unless of course there is a real show stopper like the JTAG gets fused off in the silicon or there is a lack of documentation available from the SoC vendor to get it working.

Thanks! That was really informative.

One minor comments regadring the Dragonboard Documentation referenced by Steve in his above e-mail:,

I just read the text from the Dragonboard:
On page 13 of the DragonBoard Hardware Manual: “APQ8016 SoC JTAG interface is routed to J15. If the use of JTAG is required, J8 need to be soldered to the board. The connections and connector pitch meets the 96Boards specification for the JTAG interface.”

and I think there is a minor error in the following statement: … J8 need to be soldered to the board…
Since J8 in Section 1.1 Board Overview is the Low Speed Expansion Connnector

So the Dragonboard Docu should say … J15 need to be soldered to the board … ?

In addition looking at J15 on my Dragonboard it looks that one needs a 2x10 Header like the FTSH-110-01-L-DV, versus the 2x5 Header FTSH-105-01-L-DV mentioned in the Hikey Docu. I nealry overlooked this.


I ordered a FTSH-110-01-L-DV for the Dragonboard, and that is not the correct connector. A much finer pitch connector is needed. The FTSH-105-01-L-DV appears to be correct for the HiKey board.

DEL, wrong thread, sorry.


since my last post, I got OpenOCD and JTAG on HiKey working :slight_smile: I know your original question is regarding DragonBoard, but the wiki page, and code could be a good basis for getting something working on that board also.

Please see the wiki page here https://github.com/96boards/documentation/wiki/JTAG-on-HiKey

I do intend to try it on the Dragonboard as soon as one arrives (predicted delivery is currently middle to end of August) which happens to nicely coincide with the end of my holiday.



That is awesome! I do have all the tools already, and I don’t have strong preference between the boards. As long as ARMv8 is there, I’m fine.

Please keep me posted on any updates!

Sorry for Necroposting - @dpc I did some progress in that matter if you’re still interested.

TL;DR version: It works, but you need Trace32 (at least for now).

I posted all the details I have for now on the mailing list:

Thanks for the info! Too bad it’s so expensive. :slight_smile:

@dpc - there is a chance, see next my mail in thread on mailing list :slight_smile:
But I’m not able to focus too much on that for now.

Hello everybody,

thanks for share these information.
Do you know what device corresponds to ID=Ox000016dd after the jtag boundary scan please? the emmc maybe? the pmic?

Info : JTAG tap: apq.dap tap/device found: 0x5ba00477 (mfg: 0x23b, part: 0xba00, ver: 0x5)
Info : JTAG tap: auto1.un1 tap/device found: 0x000016dd (mfg: 0x36e, part: 0x0001, ver: 0x0)
Info : JTAG tap: hexagon.un2 tap/device found: 0x007060e1 (mfg: 0x070, part: 0x0706, ver: 0x0)
Info : apq1: hardware has 6 breakpoints, 4 watchpoints

Thanks and merry Christmas :-)!