Reset/Dragon Interface

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How are people designing their Dragon Interface and mixing it with their reset button/filter?

Typically I use a Switch and a pullup resistor with a .1uf cap to ground, the docs say that the .1uf cannot be hooked up wihen the dragon is attached. Do you guys jumper the .1uf or just omit it?

Also does anyone have the pinout of the dragon interface so I can put a header on my board?

Just looking for ideas on my new MEGA48 project I'm working on.

Thanks,

Mycal

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The Dragon interfaces are the standard JTAG, ISP & Debug wire facilities that are defined in the datasheets of most Mega & Tiny controllers.

If you look in the "Help" section if AVRStudio SP3, build 485, 488 or 490, full details of these interfaces are fovered under the Dragon section.

As for the reset issue, I always use an external borwn-out detector (BOD). I place the RESET switch on the input of the BOD and it has no adverse effects on the RESET line, proper, of the microcontroller.

You can avoid reality, for a while.  But you can't avoid the consequences of reality! - C.W. Livingston

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I think the OP is talking about the debugwire interface, as the capacitor on the reset line screws with how debugwire works, it's not Dragon specific.

-Curiosity may have killed the cat
-But that's why they have nine lives

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Sceadwian wrote:
I think the OP is talking about the debugwire interface, as the capacitor on the reset line screws with how debugwire works, it's not Dragon specific.

Well, I can't see where the OP specified anything specific so...

You can avoid reality, for a while.  But you can't avoid the consequences of reality! - C.W. Livingston

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but why use of BOD when there is one internal to the chip? But I will look at the help section and check it out, thanks,

-lp

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mycal wrote:
but why use of BOD when there is one internal to the chip? But I will look at the help section and check it out, thanks,

-lp

I have alway used an external BOD in my designs and, always will. This comes from my MC68HC11 days. I learned a very long time ago that when it comes to EEPROM, a BOD is a very, very cheap insurance policy.

By using an external BOD device, the resistor & capacitor is placed on the BOD input and there is no capacitive loading placed directly on the RESET pin - it's isolated by the BOD device and that will illiminate the issue that seems to be present with DebugWire and capacitive loading.

If you use a BOD with an internal PULL-UP resistor, such as a Panasonic or Microchip BOD, you only have one extra component, the BOD itself.

You are asking to have the problem solved... I gave you one possible solution. You can place an external BOD device, or even a handful of descrete components on the PCB to solve the problem or, you can live with the problem as it currently exists.

Your choice !!!

You can avoid reality, for a while.  But you can't avoid the consequences of reality! - C.W. Livingston