The smallest ISP connector

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#1
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Hello,

often I develop small SMD board where the standard 100 mils 3+3 header for ISP is too large. Sometimes I also need to remove it after programming to save z-space.

A colleague of mine suggested to reduce the pitch of the header to 90 mils so you can insert and remove the connector without solder it.

What do you recommend in these situations?

I'm talking about production boards - not to develop firmware. They come with the MCU already soldered and I need to program them one time.

Marco

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I know someone who puts the JTAG connector for his very small MSP430 boards on a snap-off piece on the PCB. He just cuts it off when the board is programmed.

Leon Heller G1HSM

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I have put a row of SMT pads on the board and used a hand-held fixture with pogo pins to program some boards.
/mike

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There are finer pitch connectors available. Take a look at the AVR Raven boards and see what Atmel used.

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Before someone else mentions it - do a thread search for "pogo pins" and you'll hit a LOT of the prior threads about this.

EDIT: apologies to n1ist - I must be blind - he already mentioned this

Last Edited: Thu. Sep 2, 2010 - 08:14 PM
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For production, do not use a connector at all.. Unless it needs field updates there's no use for it, just use a SMD footprint and pogo pins or something similar.

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Did anybody mention pogo pins? That's what I'd use. ;)

I actually used one of these on a project where I had to program over 100 boards individually:
http://www.hmcelectronics.com/cgi-bin/scripts/product/7420-0001/Pomona-5250

While it worked initially, eventually the clip started to fail and I'd have to wiggle it to get ISP to work. Finally, it died and I had to connect the programmer to pins manually. A fellow freak actually warned this would happen, but alas I tried it anyway to save space.

In the future I'll be spending the time to create a programming/testing fixture. See: http://www.sparkfun.com/commerce/tutorial_info.php?tutorials_id=138

I have too many hobbies.
s-conductor.com

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Thank you, I didn't know their name was pogo pins.
I have a couple of soic-8 pogo pins by 3M which I bought some month ago.

But the ones I have got are not reliable: the pins don't connect well to the soic IC.

I'm going to try the Pomona ones.

EDIT: unfortunately they don't ship outside USA/Canada for order less than 500$ :(
I will look for pogo pins in another online store

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Sparkfun sell pogo pins

Scattered showers my arse -- Noah, 2348BC.
Rob Gray, old fart, nature photographer, embedded hardware/software designer, and serial motorhome builder, www.robgray.com

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Those IC clips are not called pogo pins, the gold springy pins in the Sparkfun link are.

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Quote:

unfortunately they don't ship outside USA/Canada

A bit closer to home for you:

http://it.farnell.com/emulation-...

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iw2nzm wrote:
I'm going to try the Pomona ones.
The Pomona clips are really nice, but they too will wear out quickly (right when you need it most). A setup with pogo-pins will last longer, and if you design it correctly you can replace the pins as they wear out.

I have too many hobbies.
s-conductor.com

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I had a board whose thickness was the same as the distance between the rows of a DB9 connector. So I brought the RST,SCK,MISO,MOSI,gnd lines to the edge of the board and made pads that were the same distance apart as the solder cups on the DB9 connector. Then I just pressed the connector onto each board for programming. It worked OK.

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Interesting that you see 2 by 3 pads inside many mice. Perhaps their ISP connectors?

274,207,281-1 The largest known Mersenne Prime

Measure twice, cry, go back to the hardware store

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mhatter wrote:
iw2nzm wrote:
I'm going to try the Pomona ones.
The Pomona clips are really nice, but they too will wear out quickly (right when you need it most). A setup with pogo-pins will last longer, and if you design it correctly you can replace the pins as they wear out.

I searched into the forum but I can't find a good setup for an AVR ISP with pogo pins.
Anyway, how they works? I need to push the pins against the board while programming, don't I?

It would be nice if I can leave the connector for some time without hands.

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Pogo pins are spring loaded PCB probes that make contact with your DUT (in your case a PCB with AVR). The pogos are inserted into an insulated carrier with a pattern that matches the programming pins on your PCB. Alignment pin holes should be added to your PCB so that the PCB will contact the probes. Your alignment pins will also need a shoulder. This is to establish the proper spring compression onto the pogos when the DUT is placed on the fixture. Usually, there is also some sort of clamp that holds the DUT to the fixture (especially for production fixtures). But, you can hold the board down by hand if your volumes aren't that high. If you don't have room for alignment pins inside the PCB outline, you can also create alignment pins outside the board perimeter, but the positioning won't be quite as accurate.

A link to a 0.050" center to center probe from IDI is shown. There are other sizes of probes and receptacles as well.

http://www.idinet.com/flash/probeload.aspx?SR=ICT&SE=50C&MD=&CP=25&PG=1&CC=11

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Thank you very much for you clear answer. Now I can figure out the situation.

by the way, the link you wrote doesn't work (404)

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Link works just fine for me.

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mhatter: I wrote a post about my similar experience and available alternatives https://dzrmo.wordpress.com/2017/07/04/chinese-soic-8-test-clips-for-in-circuit-programming-part-2/

Last Edited: Wed. Sep 13, 2017 - 06:55 PM
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This thread has been quiet for 7 years!  I think the topic has closed.

 

Jim

If you want a career with a known path - become an undertaker. Dead people don't sue! - Kartman

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB user

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Maybe the thread is not completely necro because the OP (iw2nzm) is still posting in other threads.

iw2nzm wrote:
I searched into the forum but I can't find a good setup for an AVR ISP with pogo pins.
Tag-Connect may have been created after your year '10 post.

I had one that worked great with my AVRISP mkii.

by hobbss

...

http://www.avrfreaks.net/forum/tag-connect#comment-1640206

 

"Dare to be naïve." - Buckminster Fuller

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gchapman wrote:
Tag-Connect may have been created after your year '10 post.

I met the inventor, Neil Sherman, at an exhibition in October 2010,  when it was being shown as a new product - so it wouldn't have been well-known or widely available at the time of the opening post in this thread.

 

Since then, I have used it a couple of times - see: http://www.avrfreaks.net/comment... and following posts.

 

TagConnect disconnected from target board (with mini ARM connector for reference)

(standard miniature ARM connector is also shown for reference)

 

It gets a whole thread here: http://www.avrfreaks.net/forum/t...

 

Search this site for "tagconnect" or "tag-connect" to find many other references: http://www.avrfreaks.net/search/...

 

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Often a standard FR4 fiberglass printed circuit board is about 0.1 inch (2.5mm) in thickness.  With this thickness, you can use a standard 0.1 inch dual header where the pins are in two rows and use this as a card-edge connector.  One row can be on the top side of the board and the other row on the bottom side.  On the dual header pin strip, there is usually about 0.2 inches between the tip of the header pin and the black plastic that holds the pins.   You could route the ISP traces to the edge of the board, press (but don't solder) a 2x3 or 2x5 header onto these top-and-bottom card-edges for programming, and then remove the header once the AVR has been programmed.  The pads can be any size, but their centers need to be spaced 0.1 inches apart.

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That could work for hobbyist or prototyping (done it myself), but the OP specifically stated:

I'm talking about production boards