Mass-programming microcontrollers?

InSilico

Just curious,

How are microcontrollers programmed in a mass-production situation? Let's use the Basic Stamp as an example.

The Basic Stamp has a microcontroller that is loaded with the PBASIC interpreter already. Is that microcontroller programmed before it is soldered onto the board? Is there a special programmer device that can program many chips at once? How are the SMD devices programmed since I don't see a breakout to accept a programmer anywhere.

Especially for the Basic Stamps powered with an SX microcontroller, do you Parallax people have a special sx-key you designed for mass production? I can't imagine having to program each chip one at a time with a single SX-Key!

Leon

Gang programmers can program several chips at the same time time with the same program.

The Basic Stamp probably uses a mask-programmed chip, that is programmed by the manufacturer when it is made.

Leon

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Timothy D. Swieter

Further to Leon's point. There are manual gang programmers where an operator places ICs in programming sockets and the programming starts. There are also automatic programmers that you feed a tube or reel of ICs into and the other side of the machine spits out programmed parts.

Some production runs may use ICP - in circuit programming and program the part using a test jig that makes contacts with pin or pads on the IC or MCU or special headers on the PCB could be used too.

Other design - seriously high volume designs with locked code has the code permanently placed in the IC like Leon stated.

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Timothy D. Swieter, E.I.
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Brian Carpenter

i have seen the machine that Parallax uses and it is just as Timothy suggests. It is an automated machine that takes the tubes and programs the IC. Parallax offers a service (or used to) where they will program your SX chips for you at a per ic cost. It is really a good value when you figure it takes a full minute or two to do it in circuit yourself

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It's Only A Stupid Question If You Have Not Googled It First!!

Phil Pilgrim (PhiPi)

In the designs that I do using AVRs, the AVRs are programmed in-circuit as part of the production test procedure. (One of the reasons I choose 8-pin AVRs over PICs is that they're a lot friendlier for in-circuit programming.) In the MoBoStamp-pe, for example, the AVR coprocessors are programmed (and can be reprogrammed by the user) with a BASIC Stamp program. Smaller modules, like the SoundPAL, use a cabled SOIC gripper clip that grabs all eight pins, powers the AVR, and programs it from an external BASIC Stamp. You do have to be a little careful what's connected to the programming pins, though. In a design that I'm currently working on, all three programming pins are connected to LED cathodes. With a 5V supply, the current required to pull the pins down was too much for the programmer. Switching to 3.3V fixed the problem. (It's actually fun to watch the LEDs twinkle as the chip is being programmed!)

One reason I favor in-circuit programming is that it makes updating the firmware possible without replacing the micro. Some of Parallax's other products have "pogo pin" pads for (re)programming the onboard SXs. Attached is a photo illustrating these on the GPS and Ping))) units. Even without them, all you would need for an SX is to power it up and clamp onto the ends of the resonator to program it.

-Phil
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Leon

I know someone who designs his PCBs with a little break off section which has the pads for programming. When programmed, the section is chopped off. His boards have to be as small as possible.

Leon

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Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle