SimmStick Bus Specification
SimmStick(tm) started with a PIC 16F84 Single Board Computer designed by Antti Lukats from Estonia based around the 30pin SIMM socket used on PC motherboards. The initial bus design was versatile enough that in addition to the PIC16F84-based design, there are now boards for 20 & 40 pin Atmel AVR and non-AVR micros.
Boards are re-usable and reconfigurable for many different applications. You can prototype a design on a breadboard with a 30 pin Simm Socket for your PIC16Cxx or Atmel micro, then a final board design can include or exclude the SimmStick module.
The best part is the price - about $6USD per bare printed circuit board for single quantities. This is for a 3.5" by 1" double-sided, plated-through, solder-masked board.
The DT001 8 slot Development Platform also contains an inexpensive PIC programmer for the SimmStick bus.
A SimmStick bus structure isn't a definite requirement as these modules can also be connected together with straight or right angle 30 pin male and female pins, as a set of header pin holes are provided just behind the edge connector pads.
A DT Series Board 2 Inch Simmstick is 2.025" high and has the top
holes .175" from the top edge.
A DT Series Board 2.5 Inch Simmstick is 2.65" high and has the
top holes .175" from the top edge.
What are the 3 special I/O lines used for?
Why connect D0 to D15 together on the motherboards?
On larger applications, or where multi-processors are used, you may need to
custom design or jumper a motherboard to suit.
If you need to design and manufacture a custom motherboard and use off the shelf SimmSticks, then future design is easy. You don't need to cut tracks and run jumpers on SimmSticks if you do all your configuration on the motherboard.
More info can be found at: http://www.simmstick.com
simm sockets, etc.
I have used the DT101 and DT001/DT003/004 for a number of projects. One I remember had a DT003 connected to a number of peripherals with a 16F84 on a DT101 simmstick. I continually modified and expanded on what it could do d display, and in so doing must have moved the DT101 from the DT003 based product to the DT001 programmer board hundreds of times.
Never a hickup and examination of the sockets/contacts shows no appreciable wear. The advantage of the DT101 socket is that it is pressed together with no sliding (read scraping) motion.
Simm Socket Footprint
Yes, the simple PIC stuff is pretty "low-cost", but you must realise it has limited memory and I/O capacity. As you start to get to the 40-pin chips with plenty of I/O and more memory, costs start to escalate toward the "other" controller boards.
> I found some terms that I didn't know, one of which was SimmSticks.
At risk of repetition, as others have replied, these use the format of 30-pin SIMM memory cards. The PCBs are small, fairly easily produced (but not D-I-Y) and the SIMM sockets are dirt cheap from disposals outlets. It makes for a neat means of stacking modules; the "motherboard" can even be Vero®. (A fibreglass laminate version of Vero would be **really* nice...)
> I get hit with the fact that I must pay for some sort of controller
Maybe, maybe not. *Any* parts can be hard to find, and many old parts such as the Z-80 are pretty cheap. Most of the CMOS processors, which are almost always the ones you want for economy of power, are still current, but priced proportional to their capabilities. The trick in the Atmel AVR and PIC16F84 parts is that they are easily reprogrammable *and* fairly cheap.
> or the STAMP module which is out of my price range.
That very much depends on how many you want. You can hack a single Stamp module into a design much more cheaply and easily than building Don's system; the module is complete and the software off the Web; you need very little else. You can cobble together a PIC'84 programmer *much* cheaper than Don's however, but you won't have an application board. (Maybe you could use his DT-101s and cobble a version of the DT-001, but I doubt it'd be worth the mess!)
Once you've got the DT-001 up and running though, DT-101 modules *are* going to be cheaper and more versatile than Stamps though and you get an excellent base controller. Neither contains interface as such (but Don does those too).
> I guess what I'm asking is would someone please give me a little help
Done it? - not at this point. I'd say though they are at worst, equal to the Stamp (but you have to learn Assembler instead of Stamp "Basic") and I'd advise you to go for it.
> a few small dc motors,
You'll have to build drivers (whichever way you go) unless you can use standard servos (worth considering; cost starts to mount).
> some simple sensors circuits,
Pretty much processor-independent. Pin count has to be monitored. A clever trick is to have your sensor board contain a parallel-in, serial- out shift register to clock in 8 or more inputs on only three lines.
> decent progamable memory size, expandable and upgradeable
1K of PIC instructions goes a fair way; if you can learn to write the interface to external serial EEPROM you can have 8K or so of token code on the DT-101, or there is a form of Stamp-like "Basic" to do this.
> The controllers usually used by many robot buffs are STAMP's,
I think you can better the Stamp with Don's stuff fairly well. The others you mention, particularly the Botboard however are not comparable to my mind. You are getting there to 68HC11 boards with major memory resources (32K or more) and much more I/O, programmable in FORTH which is still ace for robots. They are almost certainly worth the money, when you need them.
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