cheap and small programming header

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Dren
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Posted by Dren: Thu. Oct 14, 2010 - 01:03 PM
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Hello All,

I am looking for a cheap way to connect an ISP to a PCB. The project is making a LOAD of PCBs and we want to save the cost of a connector and the real estate of 0.1" pitch.

I thought of laying out some pads and pressing some spring loaded (pogo) pins onto them. I could have a test jig built, but I would rather have a way of clipping a programming header directly onto the PCB.

A few years ago there was a neat little header that came from a 3rd party dev kit for PICs. The PCBS were laid out with small pads and a few holes and this connector clipped through the PCB and was remarkable well fixed. Does anyone know where I could find something like this ?

Any constructive ideas always welcome

Dren :)

<º))))><

I am only one lab accident away from becoming a super villain.

Tags:

AVR Microcontrollers, megaAVR and tinyAVR
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clawson
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Posted by clawson: Thu. Oct 14, 2010 - 01:09 PM
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Pads and Pogo Pins is the usual solution. Perhaps even using pre-existing thru hole vias or test pads.

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millwood
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Posted by millwood: Thu. Oct 14, 2010 - 01:55 PM
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I use those hook-up wires: very easy to solder, remain flexible forever, and always provide good contact. when I don't need them, I would put the insulation sleeves back on them.

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theusch
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Posted by theusch: Thu. Oct 14, 2010 - 02:07 PM
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Quote:

The project is making a LOAD of PCBs

A good/best answer depends on what a LOAD is.

If in 5 figures, give-or-take, then a good answer is to get the AVRs pre-programmed from the distributor.

Another good answer for those levels of production is to see what facilities the board house has. They may be able to program the AVRs on the way to the pick-and-place machines.

For my quantities, measured in 3 figures per batch, traditional ISP with test code at the board house is common. Good-old [much maligned] cheap ATAVRISP2. We use a single row of six 0.1" spacing holes, and adapt the tail of the MkII. (We used to use 2mm.)

Either a keyed header is mounted, or the holes are just left naked and a row of header pins is inserted, held sideways to maintain contact, and Program All.

In total there are many thousands of AVRs each year programmed this way for our production apps. 1000+/month.

The space for the holes is a problem only on the tightest of apps. Those signals tend to be close to each other on an AVR anyway.

Oh, yeah--what package are you using? For DIPs and even most SOIC styles, a test clip works quite well.

Lee

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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Dren
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Posted by Dren: Thu. Oct 14, 2010 - 02:48 PM
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LOADS is well over 10K, probably several 100K, who knows we may break the 1M mark if the sales guys pull their fingers out and we are allowed to supply them to South America.

Sadly we can't do any outside construction or even programming as they are used in a secure military project and they are red hot about this sort of thing :( Some will also need individual programming due to encryption, security and functionality. I hate military stuff by the way, I object to it on moral/ethical grounds, but for a whole series of little steps that made sense at the time - here I am ! (The road to hell is paved with good intentions).

It not going to be allowed to tack some wires onto the PCBs, and that's not a good plan anyway. The press pins seems to be the best solution, however, my colleague is looking into the possibility of sharing the programming pins onto one of the inter-PCB connectors.

I was really looking for a press on connector that was fixed to the PCB. Something like this :

http://www.tag-connect.com/

But with smaller fixing holes.

<º))))><

I am only one lab accident away from becoming a super villain.

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mbotherway
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Posted by mbotherway: Thu. Oct 14, 2010 - 11:35 PM
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The tag-connect looks awesome. Might have to try and use them on future designs. I too just use a 0.1" 6 way DIL header, without the header. Just insert the pins, give slight sideways pressure and program.

Is the no-legs tag-connect still too big?

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gchapman
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Posted by gchapman: Thu. Oct 14, 2010 - 11:46 PM
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"PogoBeds: SparkFun Production and Testing"
http://www.sparkfun.com/commerce/tutorial_info.php?tutorials_id=138

"Dare to be naïve." - Buckminster Fuller

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valusoft
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Posted by valusoft: Fri. Oct 15, 2010 - 12:52 AM
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Is a set of edge connector contacts out of the question?

Ross McKenzie ValuSoft Melbourne Australia

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Dren
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Posted by Dren: Thu. Oct 21, 2010 - 01:08 PM
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The Tiny is inside a screened case, so we can't take any connections to the edge of the PCB without EMC problems. I think that we will go with the http://www.tag-connect.com/ solution, and have to live with pushing the connector on rather than clipping it.

I like the Sparkfun programming bench, until you don't have any PCBs on it and lean on the pins :S !

<º))))><

I am only one lab accident away from becoming a super villain.

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dksmall
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Posted by dksmall: Thu. Oct 21, 2010 - 03:48 PM
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Dren wrote:

I like the Sparkfun programming bench, until you don't have any PCBs on it and lean on the pins :S !

Ah yes, memories of years doing in-circuit test developments with bed-of-nails fixtures. Had to use a needle probe once in awhile in tight locations, and darn it if they aren't a little taller then the standard probes, so you'd get pricked all the time! Ouch!!

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John_A_Brown
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Posted by John_A_Brown: Thu. Oct 21, 2010 - 05:49 PM
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Quote:
Sadly we can't do any outside construction or even programming as they are used in a secure military project and they are red hot about this sort of thing

As you probably already know, an ATTiny is never going to be that secure.

Four legs good, two legs bad, three legs stable.

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frankvh
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Posted by frankvh: Thu. Oct 21, 2010 - 10:41 PM
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We use the much shorter versions of the pogo pins, from MilMax (called spring-loaded headers) available at Digikey and other places. The same basic concept as the pogo pins, but shorter and much less susceptible to being damaged. Then just some pads on the bottom of the PCB for the springy header to push up against.

http://www.frankvh.com

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gchapman
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Posted by gchapman: Fri. Oct 22, 2010 - 12:21 AM
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frankvh wrote:
We use the much shorter versions of the pogo pins, from MilMax (called spring-loaded headers) ...
Mill-Max's intro to these:
http://www.mill-max.com/images/products/pdf/005N.pdf

"Dare to be naïve." - Buckminster Fuller

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split63
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Posted by split63: Tue. Aug 18, 2015 - 10:50 PM
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Dren wrote:

I am looking for a cheap way to connect an ISP to a PCB. The project is making a LOAD of PCBs and we want to save the cost of a connector and the real estate of 0.1" pitch.

I thought of laying out some pads and pressing some spring loaded (pogo) pins onto them. I could have a test jig built, but I would rather have a way of clipping a programming header directly onto the PCB.

 

Anyone find a solution for this?  We already have a 2x6 0.1" hole pattern on our PCB and we would like to push-in, snap-on, a temporary cable to program AVRs.  Our product has been shipping for years, and we would like something that is retroactive....so we can't change the PCB.

 

Here is a solution, but I'm looking for something that can me made into a commercial low cost, simple cable

 

Last Edited: Tue. Aug 18, 2015 - 10:58 PM
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awneil
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Posted by awneil: Tue. Aug 18, 2015 - 11:28 PM (Reply to #14)
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split63 wrote:
I'm looking for something that can me made into a commercial low cost, simple cable

Look no further - it already has: https://www.avrfreaks.net/comment...

 

 

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split63
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Posted by split63: Wed. Aug 19, 2015 - 02:19 AM (Reply to #15)
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That Tag connector requires a special board layout.   I'm working with existing boards as stated above.
 

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awneil
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Posted by awneil: Wed. Aug 19, 2015 - 05:54 AM
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https://www.sparkfun.com/product...

 

https://www.tindie.com/products/...

 

http://protofusion.org/wordpress...

 

 

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  3. Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
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Who-me
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Posted by Who-me: Wed. Aug 19, 2015 - 06:23 AM
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Dren wrote:

 and we want to save the cost of a connector and the real estate of 0.1" pitch.

 

Another very compact and low cost approach is to use standard 0.05" pin headers, and a clothes-peg means of PCB connect, to a row of 0.05" spaced holes.

 

The holes give positive location, and the spring action ensures all pins contact.

If you do not want the spring, an alternative is to stagger the holes very slightly, so the pins friction lock going in.

Accept some finite life on the pins+carrier PCB & treat it as a consumable.

 

We have also used clips straight over gull wing MCUs.

 

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split63
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Posted by split63: Wed. Aug 19, 2015 - 03:17 PM (Reply to #17)
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Was hoping for something that did not use high cost pogo pins.   I was envisioning a pin shape that split in half and then rejoined.....looks like a squashed letter "O".   As the pin is inserted into the hole the split shape deforms to tightly grip the hole.   I know I have seen something like this....perhaps it was a Press-pin design.....update...see picture below.   Unfortunately, the pins shown are press-fit and would never push into existing holes by hand.  Plus press-fit are meant to be permanent.   But you get the idea, something more pliable/flexible that would push in by hand provide adequate temporary contact....just long enough to program.

 

 

 

Last Edited: Wed. Aug 19, 2015 - 04:04 PM
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Torby
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Posted by Torby: Wed. Aug 19, 2015 - 10:00 PM
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You  can just put through holes for a header, but not populate it. Then stick a header in your ISP, poke it into the holes and apply a little torque to jam the pins in the holes.

The largest known prime number: 282589933-1

It's easy to stop breaking the 10th commandment! Break the 8th instead. 

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split63
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Posted by split63: Wed. Aug 19, 2015 - 10:13 PM
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Yep, that is what I do now, but I want something even a customer could use.

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Torby
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Posted by Torby: Thu. Aug 20, 2015 - 12:56 AM (Reply to #21)
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split63 wrote:

Yep, that is what I do now, but I want something even a customer could use.

 

Now THAT's a different can of worms!

The largest known prime number: 282589933-1

It's easy to stop breaking the 10th commandment! Break the 8th instead. 

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Who-me
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Posted by Who-me: Thu. Aug 20, 2015 - 04:03 AM (Reply to #19)
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split63 wrote:

 But you get the idea, something more pliable/flexible that would push in by hand provide adequate temporary contact....just long enough to program.

 

See my post above, - if you stagger the holes carefully, a std pin header 0.1" or 0.05" will 'friction lock' into the holes, using the springiness of the pins.

Press-pins as you show, can do the same, if you carefully size the holes, and stagger.

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valusoft
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Posted by valusoft: Thu. Aug 20, 2015 - 04:37 AM
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You can read about the staggered (offset) holes idea here.

 

https://www.sparkfun.com/tutoria...

 

Ross McKenzie ValuSoft Melbourne Australia

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