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I'm struggling to find a decent way to program a production run of some boards. The boards are going to be about 2cm by 3cm ovals with a surface mount SOIC 8 pin Atmel attiny13a microcontroller. The board is too small to have jumpers and jumpers are too expensive anyway.

This is a small production run of about 1000, but will lead to a greater production run.

What is the cheapest/easiest way to program these without adding any physical components to my board besides copper traces/pads?

If there is no easy way, how much extra would it cost to buy my attiny13a microcontrollers preprogrammed? And where could I buy them like this?

Thanks!

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You likely want something like a Tag-Connect:

tag-connect

They're available in 6 and 10 pin versions, with and without the plastic retaining clips. You can find them at places like Digikey. They are not cheap ($35), but you'd only need to buy a couple to program a ton of boards.

As a side note: I think when you say "jumpers" you really mean "headers". Headers are the pins, jumpers are usually blocks that short pairs of those pins.

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  • \$\begingroup\$ Ahh. Yes I meant jumpers. I have done too many silkscreens with header's reference designators starting with J... Thanks. And those Tag-Connects are really useful! Thanks for sharing this. Unfortunately though, my board is covered on one side, so whatever I connect to it can't go through the board... \$\endgroup\$ – Unsure Pony Aug 21 '12 at 20:03
  • \$\begingroup\$ Do you mean to type "yes I meant headers"? Trying to discuss technical things gets very confusing if you're using the wrong words! \$\endgroup\$ – Jim Paris Aug 21 '12 at 20:35
  • \$\begingroup\$ Regarding tag-connect: you could always cut the leads that go through the board, so that they still go into the board (for alignment) but don't protrude through it. \$\endgroup\$ – Jim Paris Aug 21 '12 at 20:36
  • \$\begingroup\$ hahaha "yes I meant headers" is correct... And, arent the leads that go through the board spring loaded or something? I feel like you would have to hold the connector tightly against the board during the programming which would get tedious for 1000+ boards. It seems to me that something like the soic clip would be better since you wouldn't have to hold it? Or am I not understanding this tag-connector?: tme.eu/en/katalog/pom-5250_klips-pomiarowy-soico8/… \$\endgroup\$ – Unsure Pony Aug 22 '12 at 0:23
  • \$\begingroup\$ The leads that go through the board are just metal pegs -- it's the 6 (or 10) gold pins that are spring loaded. It doesn't take much force to hold it against the board, and usually it's only a few seconds to program a micro. We've had our production house using them for a while and they seem to like them. \$\endgroup\$ – Jim Paris Aug 22 '12 at 13:46
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You might be able to buy them preprogrammed from vendors like Arrow as a value added http://www.arrownac.com/services-tools/physical-value-add/device-programming.html. I know Microchip provides this service directly, but I can't find that option on the Atmel site. I believe Microchip charges somewhere between a dime and a quarter (US) per unit for the service. Some assemblers I've used also offer this service at a similar price, depending on the specific microcontroller. If you use this sort of route, I highly recommend getting and testing a programmed sample before doing a run.

I use and like the Tag Connect. For me, I often include them on PCBs even if preprogrammed MCUs are used. Relaxes me to think that if I screwed up the firmware, I can reprogram, even if it takes a long time.

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I've only ever used ISP clips for interfacing to logic analyzers for test purposes. But as long as none of the surrounding circuitry will mind the programming signals, there should be no reason you can't use an ISP clip to program the device in-circuit.

As with most things, they vary in price:

Expensive

Not So Expensive

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Ask 10 people for advise on this and you'll get at least 11 answers!

Here are some options:

  1. Buy them programmed from the disty.
  2. Get a bed-of-nails test fixture made, where each nail contacts a small randomly placed test point on the PCB. This could also apply power. This method is most useful for high volume production. It might be possible to program a whole panel of PCB's with the same bed of nails fixture.
  3. Use something like the Tag-Connect connector that Jim Paris mentioned, or something similar.
  4. Use an edge-card connector. This requires nothing more than pads on your PCB. There are edge connectors with as few as 10 pins available. This takes the most PCB space of all options, but allows the use of cheap connectors and can bring out more signals than others. You can bring out serial ports, power, reset, led's and other signals to a small "debug and production" board that might be useful. I've used this method for bringing up prototypes as well as production and it works well. Pay attention to the number of mating cycles for the edge connector and plan on replacing them regularly.

Usually the most appropriate method is the one that fits in best with your manufacturing line. Some places normally use a bed-of-nails so that would be appropriate for that factory. Places that are not so automated might prefer the Tag-Connect thing. Etc.

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