SimmSticks - Why?

I have been out of the hardware scene for a while.
While getting up to speed, I have noticed that the "SimmSticks" seem to be insanely popular.
Perhaps I am just missing the obvious - however, I have some questions:
1. Many Simm sockets have a minimum life expectancy of 25 insertions. After that you are on borrowed time. Has anyone noticed a problem in this area during prototyping?
2. I don't see what the spectacular advantage is over using the little .100 single and dual headers and stacking the boards together. Back in the day (> 10 years) this was *the* method we used for Z80 and 68HC11 boards and I/O.
If we were protyping, we let friction hold them together. For permanent use, we fastened them together with standoffs.
3. Lastly, in this modern day of space travel and microwave ovens, why hasn't SPI or I2C become the bus of choice for uC projects. No backplane required, few wires, almost unlimited I/O address range...
I'm probably doing a lot of point missing. Cal C.
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Cal Craughton wrote:

Not everybody is that fond of them. I use them because the Systronix products I use are based on the SimmStick form factor.

Ayup.
This is why I am going to do this to my Systronix JStik.

Ayup.
I use SPI on the SimmStik bus for most of my communication.
I want to design a bus around this sort of thing.

The SimmStick is a standard of sorts, and people like standards.

-- D. Jay Newman http://enerd.ws/robots /
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On Thu, 11 Sep 2003 01:30:05 GMT, "D. Jay Newman"
-snippage-

You know the saying - the great thing about standards is that there are so many.
I wouldn't mind someone coming up with a _new_ pseudo standard. Business card sized? Credit card sized?
Maybe both 4"x4" and 2"x4" PCBs? With .100 headers at each end of the 2"x4"?. I am thinking the 4"x4" would be more for I/O boards. (room to mount opto22 type stuff)
Cal
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I'd like the headers to have a standardized pinout, so that you could stack them similar to PC104 and have power, SPI, I2C, and I/O ports running up the stack. Bottom layer can be your microcontroller, and then add on boards as needed. The 2x4 board would have a subset of the signals, so you could stack it on a 4x4 board. Even better to have certain groups of pins set aside for sensors, motor control, etc so you can just plug in someone else's board and have a good chance of it working.
No different than a lot of us have done for millions of years already, but there's no hobby-wide standard like that.
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Garrett Mace wrote:

I'd probably differ in the technical details, but otherwise I like this.
I think it could be done.
I'm not even sure I'd have the 4x2 PCB have a subset, though I'd put a header on the long end just to have support.
It would be interesting to design such a thing. -- D. Jay Newman http://enerd.ws/robots /
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It's very simple to design, the interesting part is getting everyone to agree on it.
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wrote:

If there is enough interest, I would propose that we start a SIG of some sort. Perhaps on SourceForge? - assuming that this is an "open" project.
Someone with more imagination than me can come up with a nifty name like "Open Robotic Bus Standard"...
Cal
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Garrett Mace wrote:

I'd say the *difficult* part is the agreement.
I think when I have time I'll just work up a design and prototype and then let people know, after releasing the entire specs open-source.
I've seen too many group-designed projects come to nothing because of this type of disagreement. -- D. Jay Newman http://enerd.ws/robots /
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Ok, but I think there should be hard standards and loose standards in this...for example, power and I2C are hard standards which are always on the same pins. The soft standards would be "heavily suggested" such that one group of eight pins is usually associated with the interrupt-settable pins on a microcontroller, another group of pins is usually set up for motor control signals, etc. And of course a group of pins completely up for grabs, with a machine-pin DIP socket to route the signals with jumper wires.
But you probably don't agree! Yes, it's best if one person designs it and then everyone either agrees to use it or isn't part of the club.
Nice thing about this idea: consider what would happen if a set of boards were designed for some common microcontrollers, motor drivers, and generic I/O. The robotics community as a whole could order the PCBs in bulk, thus getting a VAST discount!
Could the robotics community (if there really is one!) coordinate this? Maybe. It would be a first. Loners tend to dominate here.
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the
grabs,
As a starting point you might take a look at: http://www.rcs.hu/simm-sys/index.htm . This is a simple bus definition along your guidelines: some hard-defined pins and some not-so-hard defined pins. You can find the documentation here: http://www.rcs.hu/simm-sys/documents.htm . We've already designed a couple of CPU/Peripherial cards for this bus and so far it proved to be useful. It's currently a 72-pin SIMM module design though we have plans to release a version with a 72-pin '100 header (and a slightly different pinout). If you plan to adopt this bus standard, you're more than welcome: the interface is free (as in freedom) for you to use it for whatever you whish. The products we have might have a stricter license but that's irrelevant in this thread...
Regards, Andras Tantos
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<snip>

Ok, I understand your viewpoint. However, I am needing some Z8 Encore boards for my own purposes. In order to help recover some of the cost, I would like to sell the extra boards.
So, before I send the plots off to the board house, I would like to hear what other people would like to see in form-factor, headers, and onboard additions (like MAX232, LEDs, etc). This is why I would like a standard of some sort. I would rather make a separate MAX232 board that just stacks on the headers...
-dave
-- David Tillman
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On 18 Sep 2003 09:07:13 -0500, David Tillman spake:

I would like an economical 2" x 3.5" pcb with headers for power, SPI, I2C, and general I/O. Perhaps room for a max-232 type chip also, but that is more optional. Incoming power should be able to take 24VDC and have onboard regulator(s) for the processor and periphs.
-------------
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I was thinking about laying out some Z8 Encore boards in a few weeks. If it looks like things might gel up somewhat, I might wait and try to incorporate this design.
-dave
-- David Tillman "Panic now and avoid the rush!"
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I would like to see this also. In particular, I would like:
1. A multi-purpose address and data bus - big enough that I can at least swap between 8 and 16 bit mcu's. (which would be I/O also)
2. As you noted, power, SPI, and I2C.
3. I don't think it would be a terrible crime to allow two clocks in the bus. (but that is just for my own quirks)
4. Some sort of bus control where I can have more than one processor on the bus. (so that I can have a DSP tell the MCU what it thinks about the situation. Now that I think about it, that would probably be better handled by I2C)
-dave
-- David Tillman "Don't Panic!" (there will be plenty of time for that later)
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David Tillman wrote:

Well, this really isn't a computer bus, but rather a controller bus.
Perhaps 32 bits of general I/O.
SPI/I2C with 8 chip select lines. Four of these could also go out to external connections.
Hmmm. I'm not a big one for clocking on a bus. Improper use of that was one of the SimmStick's biggest problems. But it really wouldn't hurt that much to have clocks.
I agree that the bus control could be done easier w/SPI/I2C.
Also at least two standard serial connections. -- D. Jay Newman http://enerd.ws/robots /
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Cal Craughton wrote:

http://www.dontronics.com/simcon.html http://www.dontronics.com/ssinfo.html
we have had them on the market for about 7 years.
socket endurance? http://www.dontronics.com/ssinfo_dg.html#cycle

you can do this with these boards too, you don't have to use the sockets at all. There is a row of holes behind the edge connector see: http://www.dontronics.com/simcon.html

yes, cable clamps or whatever, we do this too.

SimmStick uses these buses also, as well as several third party products that have USB on a SimmStick.

Hundreds of thousands of these boards have now been sold. Editorial staff at N&V, and Circuit Cellar have also used them. First commercially available proto boards for the AVR family was a SimmStick.
http://www.dontronics.com/dt006.html for the AVR family is directly supported by Imagecraft C, Codevision C, and Bascom AVR.
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