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'[PIC]: Microchip ICD 2 question - reset vector sti'
2003\08\26@134955 by Ken Pergola

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Hoping someone who has an Microchip ICD 2 can answer this question about it.

First of all, I'm definitely aware of the PICmicro device resources the ICD
2 uses but there is one question that I can't seem to find a definitive
answer to (I thought I'd try here first before calling Microchip):

Secondly, I've looked at the MPLAB on-line help regarding the ICD 2
resources and also Microchip's MPLAB ICD 2 In-Circuit Debugger User's Guide
(DS51331A). I think the answer is 'no' but I wanted to check with someone
who has an ICD 2.

The question I have is this:

When you are writing code with the ICD 2 in mind, does use of the ICD 2
require any special stipulations with regard to the reset vector -- like
putting a NOP there as the first instruction before your normal code?

Maybe I'm getting this confused with the original ICD, but unless I'm
mistaken, I think that on the original ICD there was a stipulation that the
first instruction at the reset vector must be a NOP. I'm wondering if this
stipulation still holds true for the ICD 2.

Thanks very much for your help.

Regards,

Ken Pergola

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2003\08\26@153543 by Igor Pokorny

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Hello Ken,

My two cents ..
Using 16F87x there must be NOP instruction at the address 0,  18Fxxx
doesn't  need it.  It's not about ICD / ICD2 but about hardware
implementation of a debugger to PICs.

Regards

Igor

{Original Message removed}

2003\08\26@155122 by Ken Pergola

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Hi Igor,

Thanks very much for your help. Do you know of any Microchip documents where
this is spelled out in detail? I'd like to learn more about which PICmicro
devices have this stipulation.

I just remembered to review Microchip's ON-CHIP DEBUGGER SPECIFICATION
(DS51242A) and it states:

Note: A hardware halt after reset will execute location 0x0000 and then skid
to 0x0001. Therefore, a NOP is recommended at location 0x0000.

I'm pretty certain this document came out before the PIC18 architecture so
I'm not sure if it applies to the PIC18 devices.

Thanks again Igor, I appreciate your help.

Regards,

Ken Pergola


{Original Message removed}

2003\08\26@171623 by Igor Pokorny

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Hello Ken,

look at http://www.picbook.com/bookinfo/CA4.pdf  chapter A4.2 and A4.4..
I use their project for my hobby developing and it works great

Igor

To: spam_OUTPICLISTTakeThisOuTspamMITVMA.MIT.EDU
Subject: Re: [PIC]: Microchip ICD 2 question - reset vector stipulation?


Hello Ken,

My two cents ..
Using 16F87x there must be NOP instruction at the address 0,  18Fxxx
doesn't  need it.  It's not about ICD / ICD2 but about hardware
implementation of a debugger to PICs.

Regards

Igor

{Original Message removed}

2003\08\26@193720 by Ken Pergola

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Hi Igor,

Thank you very much for the useful information -- I'm most grateful -- thank
for you for the link. This is some good information.

Take care,

Ken Pergola


{Original Message removed}

2003\08\27@042706 by Alan B. Pearce

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>I just remembered to review Microchip's ON-CHIP DEBUGGER SPECIFICATION
>(DS51242A) and it states:
>
>Note: A hardware halt after reset will execute location 0x0000 and then
skid
>to 0x0001. Therefore, a NOP is recommended at location 0x0000.
>
>I'm pretty certain this document came out before the PIC18 architecture so
>I'm not sure if it applies to the PIC18 devices.

Note that they say "recommended". I do not think it actually has to be a
NOP, but if you do a hardware reset of the chip then you will be expecting
the registers to be as specified in the datasheet for reset values, and if
you have any other instruction there, then you have a chance of the values
not being as you expect, and possibly putting yourself into a spin thinking
you have a faulty chip.

This is more to do with the way the debugger gets control than anything else
as far as I can work out from the documentation. Essentially it seems that
when in debug mode the opcode at location 0 will always be executed after a
reset, and the debug code is then jumped to, just like a special case of an
interrupt.

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2003\08\27@100512 by Ken Pergola

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Hi Alan,

Thanks Alan for your response. I've had a hard-time yesterday looking into
Microchip's web site (it's been hard to get into lately), but I plan on
searching their site for any ON-CHIP DEBUGGER SPECIFICATION for the PIC18
architecture -- the only one I could find last time I searched was for the
PIC1687x devices (of which I quoted in my post).

Anyway, thanks again for your comments.

Take care,

Ken Pergola

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2003\08\27@105540 by Alan B. Pearce

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>Thanks Alan for your response. I've had a hard-time yesterday looking into
>Microchip's web site (it's been hard to get into lately), but I plan on
>searching their site for any ON-CHIP DEBUGGER SPECIFICATION for the PIC18

I do not think that Microchip have released any spec for the 18F debugger
interface. I just assume it is very similar to the 16F87x, as it would
otherwise require a completely different set of software modules within the
ICD2 to interface the two chip families, and that does not make a great deal
of sense from the software development viewpoint.

Also what I wrote is not really gleaned from Microchip documents, but rather
my own thoughts on how the debug hardware needs to work inside the chip.

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2003\08\27@201758 by Charles Craft

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That might be what they do. When you change chip families
MPLAB notices and asks to reprogram the ICD2 firmware.

The ICD*.hex files under C:\Program Files\MPLAB IDE\ICD2

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

I do not think that Microchip have released any spec for the 18F debugger
interface. I just assume it is very similar to the 16F87x, as it would
otherwise require a completely different set of software modules within
the
ICD2 to interface the two chip families, and that does not make a great
deal
of sense from the software development viewpoint.

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