AVR-Chat

Hi Folks,

Is it possible to change the output voltage on a Dragon?  I have the
unit and I'd like to hook it up to a 3.0V circuit but I'm not sure
that I can change the voltage from the Dragon and I don't want to blow
out my prototype.

Thanks,

Richard Cooke

John,

I think that's good news but how do you hook up the Dragon to the
external board?

Looking at the "Devicesheet for the ATmega48 in the Dragon's help file
it looks like pin 6 of the VCC header (on the Dragon) is connected to
pin 2 on the ISP header (also on the Dragon).  Pin 4 of the VCC header
is shown connected to the ATmega's pin 7.  

What is the purpose of the "Board" tab in the AVR Dragon dialog box? 
I see that you can adjust the ISP frequency but what is the VTarget
used for?

Thanks,

Richard Cooke

--- In AVR-Chat@yahoogroups.com, John Samperi <samperi@...> wrote:

>
> At 08:22 AM 19/04/2007, you wrote:
> >Is it possible to change the output voltage on a Dragon?
> 
> Not that I know of, unlike the STK500. The voltage output
> is 5V from the USB bus. You can put a 3V LDO regulator on your
> board and run it that way, you should be able to read the
> VTG from the Dragon in programming mode.
> 
> >I have the unit and I'd like to hook it up to a 3.0V circuit
> 
> No problem I have worked with 3.3V circuit. The Dragon uses
> the VTG voltage from the target board to adjust the it's I/O
> level, in other words the target voltage can be anything from
> 1.8V to 5V and the Dragon should work.
> 
> 
> Regards
> 
> John Samperi
> 
> ********************************************************
> Ampertronics Pty. Ltd.
> 11 Brokenwood Place Baulkham Hills, NSW 2153 AUSTRALIA
> Tel. (02) 9674-6495       Fax (02) 9674-8745
> Email: john@...
> Website  http://www.ampertronics.com.au
> *Electronic Design * Custom Products * Contract Assembly
> ********************************************************
>

At 08:22 AM 19/04/2007, you wrote:
>Is it possible to change the output voltage on a Dragon?

Not that I know of, unlike the STK500. The voltage output
is 5V from the USB bus. You can put a 3V LDO regulator on your
board and run it that way, you should be able to read the
VTG from the Dragon in programming mode.

>I have the unit and I'd like to hook it up to a 3.0V circuit

No problem I have worked with 3.3V circuit. The Dragon uses
the VTG voltage from the target board to adjust the it's I/O
level, in other words the target voltage can be anything from
1.8V to 5V and the Dragon should work.


Regards

John Samperi

********************************************************
Ampertronics Pty. Ltd.
11 Brokenwood Place Baulkham Hills, NSW 2153 AUSTRALIA
Tel. (02) 9674-6495       Fax (02) 9674-8745
Email: john@ampertronics.com.au
Website  http://www.ampertronics.com.au
*Electronic Design * Custom Products * Contract Assembly
********************************************************

At 08:52 AM 19/04/2007, you wrote:
>how do you hook up the Dragon to the
>external board?

It's the standard ISP setup, it is well documented in the STK500
docs.

>Looking at the "Devicesheet for the ATmega48

If you are using the M48 go to my website's download page
and have a look at the MTERM2 diagram and the ISP connector (PROG).
The board shows the M8 but it is pin compatible with the M48/88/168
series also. REMEMBER NOT to put the cap (C9) in the reset pin if you
intend to use DW for debugging

>I see that you can adjust the ISP frequency

Set it at 250KHz as it will work with all chip with a clock
of >1 MHz

>but what is the VTarget used for?

With the Dragon is shows what voltage the target is running at.
With the STK500 which has a VTG output you can actually set the
prototype area voltage.

Regards

John Samperi

********************************************************
Ampertronics Pty. Ltd.
11 Brokenwood Place Baulkham Hills, NSW 2153 AUSTRALIA
Tel. (02) 9674-6495       Fax (02) 9674-8745
Email: john@ampertronics.com.au
Website  http://www.ampertronics.com.au
*Electronic Design * Custom Products * Contract Assembly
********************************************************