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#1 Nov. 25, 2005 21:42:04

Gary D.
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[avr-gcc-list] OCDEN Fuse


Hi all,I've been hunting all day to try and figure out what the OCDEN fusereally does.I have both JTAGICE (MK1 and MK2) units, and I've experimented withboth, and it seems as though it does nothing.Anybody know what this is for? Does it just give my program access tothe OCDR register, or does it do something more useful?Thanks,

Gary
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Gary Douglas
Manager - Network Products

Pathway Connectivity Inc.
Unit 103, 1439 - 17 Avenue SE
Calgary, Alberta
Canada. T2G 1J9
+1.403.243-8110 x43
www.pathwayconnect.com



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#2 Nov. 25, 2005 21:44:32

Graham D.
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[avr-gcc-list] OCDEN Fuse


Gary Douglas wrote:

> I've been hunting all day to try and figure
> out what the OCDEN fuse really does.

Doesn't it do what the data sheet says it does? I just took a look in the
ATmega16 data sheet, searched for OCDEN, and it seems pretty clear to me.
(There's not much point in me paraphrasing the data sheet, so I'll stop
here.)

Graham.



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#3 Nov. 25, 2005 22:22:50

Gary D.
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[avr-gcc-list] OCDEN Fuse


I'm sure it does, but I'm trying to figure out the application of it.The datasheet is clear, but doesn't provide an explanation of theadvantage of using it.Does AVR Studio's debugger have enhanced functionality as a result ofenabling OCD - or is it just a magic extra register (with somenotification ability) to use at will?Graham Davies wrote:Gary Douglas wrote:I've been hunting all day to try and figure
out what the OCDEN fuse really does.Doesn't it do what the data sheet says it does? I just took a look in the
ATmega16 data sheet, searched for OCDEN, and it seems pretty clear to me.
(There's not much point in me paraphrasing the data sheet, so I'll stop
here.)

Graham.



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Gary Douglas
Manager - Network Products

Pathway Connectivity Inc.
Unit 103, 1439 - 17 Avenue SE
Calgary, Alberta
Canada. T2G 1J9
+1.403.243-8110 x43
www.pathwayconnect.com



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#4 Nov. 25, 2005 22:52:33

Joerg W.
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[avr-gcc-list] OCDEN Fuse


Gary Douglas <> wrote:

> I have both JTAGICE (MK1 and MK2) units, and I've experimented with
> both, and it seems as though it does nothing.

Because the debuggers (AVR Studio as well as AVaRICE) automatically
program the fuse upon connecting to the ICE. Without this fuse being
programmed, the JTAG ICE will only have access to flash and EEPROM
page programming but nothing else.

--
cheers, J"org .-.-. --... ...-- -.. . DL8DTLhttp://www.sax.de/~joerg/NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)



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#5 Nov. 25, 2005 23:16:48

Armand t.
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[avr-gcc-list] OCDEN Fuse


On Fri, Nov 25, 2005 at 02:55:20PM -0700, Gary Douglas wrote:
> I'm sure it does, but I'm trying to figure out the application of it.
> The datasheet is clear, but doesn't provide an explanation of the
> advantage of using it.
>
> Does AVR Studio's debugger have enhanced functionality as a result of
> enabling OCD - or is it just a magic extra register (with some
> notification ability) to use at will?
>

<snip>

When the jtag ice boxes stopped succesfully the target during a debugger
session, then the target is to be in a so called debugging state. Only during
this debugging state the OCDR will be visible and the avr core will exchange
data with the jtag ice boxes. When the jtag ice boxes terminate this debugging
state then they can / will disable the OCDEN fuse bit.

AVR studio debugger doesnot know anything about this debugging state as
this will be managed only by the jtag ice boxes.
This also means that during a running application the OCDR isnot visible.

Armand

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#6 Nov. 25, 2005 23:37:07

Gary D.
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[avr-gcc-list] OCDEN Fuse


OK!

Now I get it. I was hoping for some advanced debug magic, but to no avail.

Thanks everyone.

-Gary

Joerg Wunsch wrote:Gary Douglas <> wrote:I have both JTAGICE (MK1 and MK2) units, and I've experimented with
both, and it seems as though it does nothing.Because the debuggers (AVR Studio as well as AVaRICE) automatically
program the fuse upon connecting to the ICE. Without this fuse being
programmed, the JTAG ICE will only have access to flash and EEPROM
page programming but nothing else.--
Gary Douglas
Manager - Network Products

Pathway Connectivity Inc.
Unit 103, 1439 - 17 Avenue SE
Calgary, Alberta
Canada. T2G 1J9
+1.403.243-8110 x43
www.pathwayconnect.com



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#7 Nov. 26, 2005 06:57:17

Joerg W.
Registered: 2009-11-02
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[avr-gcc-list] OCDEN Fuse


Gary Douglas <> wrote:

> Now I get it. I was hoping for some advanced debug magic, but to no
> avail.

The OCDR register can be used to exchange extra information during
debugging. AVaRICE doesn't use it. I'm not sure what AVR Studio
might use it for. At least, it's not strictly required for debugging,
everything works without that as well.

--
cheers, J"org .-.-. --... ...-- -.. . DL8DTLhttp://www.sax.de/~joerg/NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)



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