Question on PowerPC's JTAG instruction

Question on PowerPC's JTAG instruction

[John Zhou]

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Hi,

We want to design a tool to speed up our hardware diagnostics via JTAG
port.

So we have question to ask for your help:

1. How do we access PowerPC's internal GPRs and SPRs etc. via JTAG
instruction?

We'v gone through IEEE.1149.1.   There are no standard JTAG instruction to
access CPU's data bus, including internal or external data bus. Do we must
need private JTAG instruction to access CPU's internal resource? if it is,
could you share the documents with us?

2. For 'BSDL' usage, you know, we have many components on one board and much
more signals are processed specically. So, how to integrate PowerPC's BSDL
with other components' 'BSDL'?  Could you give us any hints on it? or any
document is also welcome!

Your any help is appreciated!

John Zhou

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Re: Question on PowerPC's JTAG instruction

[Laurent Pinchart]

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Hi John,

On Friday 30 May 2008 03:14, John Zhou wrote:
> Hi,
> 
> We want to design a tool to speed up our hardware diagnostics via JTAG
> port.
> 
> So we have question to ask for your help:
> 
> 1. How do we access PowerPC's internal GPRs and SPRs etc. via JTAG
> instruction?
> 
> We'v gone through IEEE.1149.1.   There are no standard JTAG instruction to
> access CPU's data bus, including internal or external data bus. Do we must
> need private JTAG instruction to access CPU's internal resource?

That's right.

> if it is, could you share the documents with us?

No public documentation is available. You will need to sign an NDA with 
Freescale (and probably pay $$$$).

I had to design a test bench to program the flash memory on our MPC8248-based 
hardware, and ended up using JTAG to bitbang the bus signals. Programming the 
processor through JTAG private instructions would have been faster.

> 2. For 'BSDL' usage, you know, we have many components on one board and much
> more signals are processed specically. So, how to integrate PowerPC's BSDL
> with other components' 'BSDL'?  Could you give us any hints on it? or any
> document is also welcome!
> 
> Your any help is appreciated!

Best regards,

-- 
Laurent Pinchart
CSE Semaphore Belgium

Chaussee de Bruxelles, 732A
B-1410 Waterloo
Belgium

T +32 (2) 387 42 59
F +32 (2) 387 42 75

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