Programmers and ISP cable length...

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#1
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Hi,

I've been using a Sure Electronics ISP programmer and also my STK500 for ISP programming and I've never really given any consideration to ISP cable length. The one coming off my Sure model is 2 feet and I routinely add another 1-2 feet to it. I've never had an issue programming even up to at 1.8mhz or so.

I'm thinking about getting a dragon, but I keep reading how sensitive it is to ISP cable length. Why would it be so much more than the sure or stk500?

I admit to not needing a long length, but it can be flexible..

Thanks,

Alan

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This must be discussed already - Dragon do is sensitive to longer ISP cables. In another words - less than 10 inches IIRC.
That's because of different buffering circuits in different programmers.

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Many programmers suffer from ringing: for MISO and MOSI that's not a killer, but for SCK it is. Read the page in my signature.

A GIF is worth a thousend words   They are called Rosa, Sylvia, Tricia, and Ulyana. You can find them https://www.linuxmint.com/

Dragon broken ? http://aplomb.nl/TechStuff/Dragon/Dragon.html for how-to-fix tips

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Quote:
I admit to not needing a long length, but it can be flexible..

I much prefer flexible cable... So much easier to work with.
If you really want long cables, just design and add your own line drivers/buffers to the output's. But do remember, small (about 4-6 inches) is beautiful :)

--greg
Still learning, don't shout at me, educate me.
Starting the fire is easy; the hardest part is learning how to keep the flame!

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Hi,

Does this have something to do with why the JTACICE mkii comes with that flexible cable with probe? Does that flexible cable do something special in terms of preventing ringing, etc?

Thanks,

Alan

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The cable is causing the ringing. The drivers must drive the cable with the correct impedance in order to prevent ringing.

A GIF is worth a thousend words   They are called Rosa, Sylvia, Tricia, and Ulyana. You can find them https://www.linuxmint.com/

Dragon broken ? http://aplomb.nl/TechStuff/Dragon/Dragon.html for how-to-fix tips

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alank2 wrote:
Does that flexible cable do something special in terms of preventing ringing, etc?

It certainly does something special to Atmel's tool division bottom line. It easily breaks and Atmel sells replacements for $39.

Stealing Proteus doesn't make you an engineer.

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Hi plons,

Does the 2.0 version of the DragonLair on your site work with the latest dragon to protect it from the outside world? Also, does the buffer you added allow for longer ISP cable lengths than the short <8" I keep reading about for the dragon?

Thanks,

Alan

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Quote:
Does the 2.0 version of the DragonLair on your site work with the latest dragon to protect it from the outside world?
Yes.
Quote:
Also, does the buffer you added allow for longer ISP cable lengths than the short <8" I keep reading about for the dragon?
That's an affirmative as well. I use 60cm cable.

A GIF is worth a thousend words   They are called Rosa, Sylvia, Tricia, and Ulyana. You can find them https://www.linuxmint.com/

Dragon broken ? http://aplomb.nl/TechStuff/Dragon/Dragon.html for how-to-fix tips

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Hi,

Plons wrote:
Yes.

That's an affirmative as well. I use 60cm cable.

Excellent.

By the way, what does the warning about "be aware of the kanda cable rotation" mean?

Thanks,

Alan

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Kanda supplied a programmer that came with the STK200 with a 10 pole connector that was 180 degrees rotated. Boooo ....
In order to "correct" that they supplied a 10 pole cable of which one of the connectors was put on rotated as well.

A GIF is worth a thousend words   They are called Rosa, Sylvia, Tricia, and Ulyana. You can find them https://www.linuxmint.com/

Dragon broken ? http://aplomb.nl/TechStuff/Dragon/Dragon.html for how-to-fix tips

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Hi Plons,

Forgive me if these questions have already been answered. I'm thinking of building a dragonlair. I'm thinking of a pcb that mounts on top of the dragon using a 2x9 (over jtag/isp) and a 2x3 (over the vtg/gnd).

1. What does the /PGM in the ISP header do?

2. I want to make the board so that the HV/target section of the dragon is still usable. I noticed your note "since HV programming is not used now there is no need to allow the /reset-line to raise to 12V". Does this mean that the dragon lair (not connected to any targets, but connected to the dragon) wouldn't tolerate HV mode?

3. Are there other headers that should be present for features the dragon supports like PDI? I looked at the PDI hardware description and it says "bidirectional half duplex" which data on the same pin as MISO, but MISO is a one way buffered into d_TDO...

4. I noticed you are using a 1x4 dW connector - is there a more standard connector like the 2x3 ISP without MOSI/MISO/SCK ? Would there be a reason to have an extra header lacking MOSI/MISO/SCK connections? The dragon docs say they will tristate these when in dW mode - is that enough to not run a seperate header for it without the connections?

5. In your note "If you don't use dW, you can replace /Reset on pin5 of P2 with /B_Reset (is on P1). That makes the Lair even tougher." could one implement a jumper/switch that switches between the "tougher" for non dW use and the "less tougher" for dW use. If PDI requires a bidirection line for data (MISO), could a jumper/switch do the same thing here? Switch between stronger (one way via buffer) or weaker (design similar to the reset)?

Thanks,

Alan

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1. For STK200
2. Unplug the protection board when you need HV programming
3. There was no Dragon-PDI when I made this; so it has not been taken care of
4. I don't know about a standard for dW. Easiest ? Make a specific cable for dW
5. There are quite a few variations one can think of.

I don't need the Dragon for PDI or HV programming; I use the STK600 for that.

A GIF is worth a thousend words   They are called Rosa, Sylvia, Tricia, and Ulyana. You can find them https://www.linuxmint.com/

Dragon broken ? http://aplomb.nl/TechStuff/Dragon/Dragon.html for how-to-fix tips

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Hi Plons,

Thanks for the answers. I started another thread with what I want to try to do in case you have any time to comment on something you haven't already answered:

https://www.avrfreaks.net/index.p...

Thanks,

Alan