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Author Topic: EJTAG for MIPS processors  (Read 2597 times)

vinifr

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EJTAG for MIPS processors
« on: April 16, 2017, 12:48:17 AM »
Hi Olimex,

Any plans to make a EJTAG for MIPS processors?


JohnS

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Re: EJTAG for MIPS processors
« Reply #1 on: April 16, 2017, 04:40:33 PM »
What extra is needed?

(Apart from software, which exists doesn't it?)

John

vinifr

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Re: EJTAG for MIPS processors
« Reply #2 on: April 16, 2017, 08:07:10 PM »
Hi Johns,

The MIPS created their own jtag interface called EJTAG: "The MIPS EJTAG is a proprietary extension", so we cannot use ARM JTAG. :(

vinifr

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Re: EJTAG for MIPS processors
« Reply #3 on: April 16, 2017, 08:11:54 PM »
Hi Johns,

The MIPS created their own jtag interface called EJTAG: "The MIPS EJTAG is a proprietary extension", so we cannot use ARM JTAG. :(

oh man, sorry, i just find out this: "Most of modern MIPS SOCs support JTAG (IEEE 1149.1)."

JohnS

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Re: EJTAG for MIPS processors
« Reply #4 on: April 16, 2017, 10:01:47 PM »
OpenOCD and others work I think.

I was wondering if there was something else like another pin not listed in any of the articles.  (I didn't find anything.)

I've used such as RT5350F, MediaTek 7688 and PIC32MX/PIC32MZ and they all seemed to work OK.

John

vinifr

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Re: EJTAG for MIPS processors
« Reply #5 on: April 16, 2017, 10:16:31 PM »
OpenOCD and others work I think.

I was wondering if there was something else like another pin not listed in any of the articles.  (I didn't find anything.)

I've used such as RT5350F, MediaTek 7688 and PIC32MX/PIC32MZ and they all seemed to work OK.

John
RT5350F, really? Great! This is the one I want to flash using jtag! Which jtag have you used? Olimex one?

JohnS

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Re: EJTAG for MIPS processors
« Reply #6 on: April 17, 2017, 09:57:20 AM »
I think it was along the lines of the wiki article.  As I recall the board had no standard JTAG pins so a rats nest of wires was needed (and maybe some pullups etc?).

Try it :)

You may need plenty of shielding as crosstalk can be a problem.

John

LubOlimex

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Re: EJTAG for MIPS processors
« Reply #7 on: April 18, 2017, 12:17:51 PM »
We use our JTAGs to upload code to RT5350F. We have also described it in the wiki article here: https://www.olimex.com/wiki/RT5350F-OLinuXino#Upload_prebuilt_images_using_programmer_tool

We had plans to create an EJTAG tool initially (it as like 5 years ago). We also have the design completed and even made and tested few prototypes. Yet, I believe at that time Imagination bought MIPS and the project was scrapped. In all honesty, we have probably worked on two times more products that what we have available, just some projects are not meant to be.

Best regards,
Lub/OLIMEX
Technical support and documentation manager at Olimex

vinifr

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Re: EJTAG for MIPS processors
« Reply #8 on: April 27, 2017, 08:16:54 PM »
We use our JTAGs to upload code to RT5350F. We have also described it in the wiki article here: https://www.olimex.com/wiki/RT5350F-OLinuXino#Upload_prebuilt_images_using_programmer_tool

Best regards,
Lub/OLIMEX

That is great! Where can I find a openocd script to debug RT5350F board?

LubOlimex

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Re: EJTAG for MIPS processors
« Reply #9 on: April 28, 2017, 02:32:26 PM »
I have no idea about an OpenOCD script, you'd have to search or post in OpenOCD's mail list about that.

We use this flashrom tool which is compatible with our OpenOCD debuggers: https://www.flashrom.org/Flashrom

Best regards,
Lub/OLIMEX
Technical support and documentation manager at Olimex