XMEGA-A1 Xplained: JTAG connector mounted too low on PCB?

Go To Last Post
8 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Happy new year 2014 to everyone!

I would like to connect the XMEGA-A1 Xplained Kit ("A09-0560/07", green PCB) to a dragon board via a 10pin ribbon cable. http://www.atmel.com/Images/doc8... (Atmel Application Note AVR1924 XMEGA-A1 Xplained Hardware User's Guide).
There is a breakout in the PCB, probably for a 'nose' of an appropriate connector (assumingly, that it may not plugged-in up-side-down).
It seems that my connectors are too thick ( http://www.reichelt.de/Pfosten-W... ) or that the 90° pinheader of the kit is mounted too close to the PCB.

Has also somebody else noticed this fact?
Or do you have better connectors types / cables?

michaeL

PS: The fugure 4.1 in http://www.atmel.com/images/doc8... shows a matching cable/connector (blue PCB).

In the beginning was the Word, and the Word was with God, and the Word was God.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

It sometimes a bit tight, but it gets better after the first use. Just apply a bit of pressure.

NOTE: I no longer actively read this forum. Please ask your question on www.eevblog.com/forum if you want my answer.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Quote:
It sometimes a bit tight, but it gets better after the first use. Just apply a bit of pressure.

Yea. that's what she said.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Quote:
There is a breakout in the PCB, probably for a 'nose' of an appropriate connector (assumingly, that it may not plugged-in up-side-down).

I am curious how exactly this "PCB key" construction could prevent IDC connector from being plugged upside-down, Michael?

Quote:
It seems that my connectors are too thick

There is a datasheet pdf on a linked site. Download, take calipers and report. The IDC connectors dimensions and tolerances are normalized (not arbitrary).

No RSTDISBL, no fun!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

You can only connect a JTAGICE-mkII round one way.
Yes, I think you can connect a regular IDC 5x2 socket both ways. However the key gives you a pretty good clue about the correct orientation.

Most Atmel boards seem to have no foolproof headers. i.e. you have to use your eyes to identify the pin#1 and read the printed legends.

David.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Quote:
However the key gives you a pretty good clue about the correct orientation.

You are pulling my leg, aren't you?

You can call and stick it the way you like but in Polish such design is called "partactwo" (derived from the noun "partacz"(sorry, no English translation).
It does not describe the reduction of material cost and low quality (like in "Made in China" nowadays) but rather the inadequate qualifications of the designer.

Quote:
It seems that my connectors are too thick

You can see that the width of an IDC female connector is 6mm +-0.1mm wide [5.9:6.1]mm so you must assume that it requires [2.9:3.1]mm from its center line to the PCB. The standard pin headers with 100mils pitch are made with 2.54mm distance from the center line (between the rows) to the edge +- tolerances.
No, your connector is not too thick, it has the size the IDC connector should have.

Quote:
or that the 90° pinheader of the kit is mounted too close to the PCB.

It is not mounted too close, it is simply a wrong connector.

No RSTDISBL, no fun!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Thanks for your feedbacks.

Also with force it was impossible to plug-in the IDC connector. After carefully bending up the pins with a screw driver the connector fits. => OK.

Quote:
I am curious how exactly this "PCB key" construction could prevent IDC connector from being plugged upside-down, Michael?

It would only work with an asymmetrical connector type, where the opposite side of the 'nose side' is higher.

But as stated in the datasheet http://www.reichelt.de/index.html?&ACTION=7&LA=3&OPEN=0&INDEX=0&FILENAME=C150%252FPFL.pdf, the connector is symmetrical with exception of the 'nose'.
@Brutte: yes, your calculation is right:
The 90° degree pin header connector is soldered so, that the black plastic fixture is lying on the PCB. => Less than 3mm distance.

Conclusion:
The commonly used female IDC connectors do not provide in conjunction with the 90° pinheaders and PCB break-out any foolproofed turn-around protection.
The break-out in the PCB has the same function like a pin 1 marking.
The hardware design is very questionable.

In the beginning was the Word, and the Word was with God, and the Word was God.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I just tried the mkII connector. You can use the grey socket either way. It just seems awkward with the ribbon coming out of the underneath. You can't use the green socket at all.

Using a Dragon with a regular IDC cable will fit both ways.

I don't have a JTAGICE-3. The whole mk3 adapter arrangement looks very delicate. I would guess that using it the 'wrong' way would guarantee a broken adapter/ribbon.

Yes. I quite agree. The hardware design is not foolproof. Atmel probably rely on enough fools to buy replacement mkII or mk3 adapters at $80 or $35. (approx prices)

David.