What is JTAG instruction register length for the ARM926EJ-S rev.5 (ARMv5TEJ) SoC

[bluestream]

What is JTAG instruction register length for the ARM926EJ-S revision 5 (ARMv5TEJ) chip?

NXP PNX8181 SoC board.

[CarlosCasillas]

Hi Andy,

Could you please try to be more specific with your question and verify the part number?

Because the ARM926EJ-S core is included on many families of NXP products.

Best regards!

/Carlos

[bluestream]

Hi Carlos,

the device is VoIP ATA adapter, the VoIP part based on
DSPGroup DVFD8187BE1ABC chip.

from kernel boot log messages:

[0.000000] Linux version 2.6.26.5 (yuzho2@Payton) (gcc version 4.1.2) #1 PREEMPT Sun Sep 6 10:54:57 CST 2015
[0.000000] CPU: ARM926EJ-S [41069265] revision 5 (ARMv5TEJ), cr=00053177
[0.000000] Machine: NXP PNX8181
... ...
[17179569.264000] Board: Vega_PNX8181_BaseStation low-cost version detected.
... ...
[17179569.264000] gpio_init: Registered PNX818 GPIO device

[CarlosCasillas]

Hi Andy,

In case of requiring support for a commercial product, please contact to the vendor of the product.

Just as complementary information, all the ARM related information could be found on ARM website, like the “ARM926EJ-S Technical Reference Manual”, available on the following link:

http://infocenter.arm.com/help/topic/com.arm.doc.ddi0198e/index.html

Hope this will be useful for you.
Best regards!
/Carlos
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[bluestream]

Hello,

this board developed by NXP, its clearly visible on kernel boot log messages. Yes, its old.

I just want to know what is instruction register (IR) length for this chip, ARM926EJ-S rev.5 (ARMv5TEJ) SoC

For some reason it not specified in ARM926EJ-S Technical Reference Manual. Or I've missing someting?

Please specify the point that describes IR length in this Manual.

Thank you.

Andy

[CarlosCasillas]

Hi Andy,

In such case, you should refer to the programming model of ARM926EJ-S core, where it is mentioned that it includes the system control coprocessor (CP15) registers, and they are 32-bit length:

http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0198e/I1003211.html

http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0198e/ch02s02s02.html

ARM instructions are 32-bit while Thumb instructions are 16-bit.

Hope this will be useful for you.
Best regards!
/Carlos
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[bluestream]

Hi,

I find another document: Arm Debug Interface Architecture Specification, ADIv5.0 to ADIv5.2
Chapter B3 "The JTAG Debug Port (JTAG-DP)", section B3.3 "IR scan chain and IR instructions".

This section describes the JTAG-DP Instruction Register (IR), accessed through the IR scan chain.

As described in B3.3.1 Required IR instructions,

The width of the IR is IMPLEMENTATION DEFINED, and can be four or eight bits.

So, IR length is 4-bit or 8-bit

More common type are 4-bit, am I correct?