Any! Combine all ideas on a board that makes everyone happy then I can check the final design for you guys.
There yu have it guys. Start your list of what you need and want.
#1) 0.1" headers
#2)
I think we ought to focus on the pins that have multiple uses and are interrupt-capable. At least one UART, at least one SPI, I2C, etc.
I think putting some of the other pins in another header is a great idea.
wow nice idea… to keep cost down do you think a simple square with 0.1" header pins sticking up on all four sides (all pins available)[no crystal, buttons…etc]
Alex: all 4 sides means you don’t get compatibility with breadboard. Is that something you’d want? Personally, I like the idea of having a semi-permanent home that I can wire/reroute as needed.
#2: crystal on board next to CPU.
#3: USBizi 144 (as that’s what I have 
Hi Brett… I dont know… maybe some ppl would like the low cost “bare bones” version. 
…ok lets add the crystal and the USB.
know what just came to my mind… the Pentium 2 Cartridge = if the typical breadboard has about [depending on manufactor] 64 pins on one side, using both sides gives us 128 [thats more tha enough for the UBizi100] but the USBizi144 will need more… thats when you can use the Top of the “Board” to access the rest of the pins( with wires) think of a Pentium 2 Cartrige with both sides insertible or flipable… the crystal, the USB conector, and the LDR button can be in the middle with the processor while its placed Vertical… hope this helps 
Socket?
http://parts.digikey.com/1/parts/411006-dev-0-5mm-pitch-100-pin-socket-b-m3a-0656g02.html
But at $330 it is a bit more than a panda… 
So how about something like this but with 100 pins?
http://iteadstudio.com/store/index.php?main_page=product_info&cPath=10_22&products_id=272
Yeah, this one fits the USBizi100…
[url]http://iteadstudio.com/store/index.php?main_page=product_info&cPath=10_22&products_id=272[/url]
just 50 pins each side,
but for the USBizi144, same 0.1" headers, but access on top for the rest of the pins… one long strip.
Think of the FEZmini in one 50pin each side board for USBizi100, and for the USBizi144 same but with 0.1" header pins along the top sides.
thats my guess or just do the compact “barebones” square… hope this helps.
But it’s only 80 pin?
I mean, we can just use the FEZmini board design; with more pins;… …
cheers.
I don’t think you should add usb to the breakout.
If you are thinking of the way it is meant: (program it, and stick it into a project) the usb would be useless and taking unneeded space.
The header pins on 4 sides is easy for projects to stick the pcb into, but not for breadboard prototyping.
If you want both (the easiness of the pins on all 4 sides and breadboard prototyping) you might need to make a rectangular pcb with pins on two sides instead of four.
Or design it in such a way that you can, if you want to use it in a breadboard, only populate two of the four headers? Then you can still add fly leads to the top/bottom pads.
You might have to add USB to the breakout board. I don’t know how happy USB will be to travel over a header, into a bread board, over some random length fly leads,back into the bread board somewhere else, over another header, and into a USB socket.
USB has some tight impedance tolerances and the trace lengths should be matched.
Regarding the usb connector I was more thinking of some sort of program pcb.
You stick the module into the program pcb and you can program it via the usb connector on the program pcb.
And then you plug it back into your breadboard?
Plugging it out of your product/breadboard to program would remove the benefit of in circuit debugging…
Which is why I put a usb connector on my “micro hex walker robot thingy” design, even though I was really tight on space. I used a micro usb connector and the connector used almost the same board space as the buck/boost regulator, but having USB was a requirement for me.
When you get down to it, is USB “optional”?
I’ve been collecting ideas for several years now for a “Small volume production-ready prototyping system”. I got quite far in writing some specs etc. and the idea is to put it in the public domain as part of OSH (Open Source Hardware).
Maybe I should resurrect this and work with you guys to come up with a wish list for a base UsbIzi module and a set of compatible peripheral modules. I really don’t like the odd pin spacing legacy from Arduino
What I’d like out of this is a general consensus on a standard footprint for modules. What goes on those modules is then open.
So here’s a screenshot of one of the base footprints - 2U in this case. A 1U, 3U etc. just becomes narrower or wider with more pins at the top.
The idea is to break out the popular Bus Pins and Power Rails at the bottom - and run those on a “motherboard” of sorts and the top row contains the Function Pins. It still remains hobby-friendly because of the 0.1" spacing.
This design has the following features (and trust me, it takes long to get to the obvious )
- Breadboard friendly - plug in the top F-row pins on the edge of a breadboard.
- Wire-wrap friendly - use the break-out pins. Yes I use Wire-Wrap - nothing beats it for speed of construction.
- Jumper-wire friendly - use the break-out pins (like Arduino/Fez)
- IDC cable friendly - use ribbon cable (like Spider)
- Perfboard (Vero-board) friendly - 0.1" spacing on all pins. Vertical buses.
- Single layer PCB friendly - You can wire 2 common buses on a single layer.
- Multi-later PCB friendly - Yes, you can wire all the buses on a 6 layer PCB (my dream!)
- Enclosure friendly. Create re-usable motherboards or pre-cut enclosures.
- Production ready - simply plug into a pre-fab motherboard or etch directly on PCB.
- Contains dedicated pins for all the popular power and data buses - including provision for PoE.
- Extensible - Add function pins at the top or new buses at the bottom while maintaining footprint compatibility.
- Small to large boards - just grow sideways.
So there you have it - SmartiBlox. If I can get some support from the community I’m sure we can start something here.
and here’s why collaborative efforts fail We haven’t agreed on long sides or square, single or multi row ;D
If you want to go with a shape like the itead breakout, then I think that would be easy to do - but not so easy on a breadboard. Certainly keeps the board size down though, so it would be easier on Eagle (there’s an 80mmx100mm limit on the version I have). I actually don’t mind that layout, but as mentioned it doesn’t really allow easy breadboarding.
What are people’s thoughts on USB? What about a specific header that will allow connecting a “daughterboard” for programming? Kind of like what you get with a USB port on a PC motherboard and a front-face USB port.
And this is what a 1U module might look like that only implements the 3V/5V rails and SPI/I2C and USB buses. Slightly bigger than the Fez Mini - and ridiculous considering all those unused pins
The point here is it is a standard pinout on all modules on the buses.
I like Brett’s idea. All pins broken out on the 4 sides of the pcb. Have a 4 pin header on the breakout board to connect a usb cable for easy programming (debugging should not be needed anymore since you’ve done that on the Panda/Domino/…). I don’t think it needs to be breadboard friendly, after all, thats where the Panda/Domino/… comes in. Use those for initial testing and debugging. The breakout board should have as only purpose to create final designs. My 2 cents…
I think you guys need to come up with a goal list like this before talking about any design:
- breadboard friendly or not
- beginner friendly or not (loader button, reset button)
- USB connector or not
- powered from USB only or through other means? How would you protect it from dual power
- USBizi100 or 144 if you need dedicated USB Host?
- ultimate goal from product is?
- how many IOs is plenty?
Designs is EASY but making decisions on a design is not easy at all