"Prop Dongle" Protoboard 1.5" x 2.75". Available for purchase!

Bean

I got this idea to make a Prop Dongle. A very small propeller development board that plugs right into a USB port (or you could use a USB extension cable) and is powered by the USB, has 12 I/Os and a small prototype area.

I will probably build some for myself, but was wondering what you guys think of it. Too small ? Too large ?

It is 2.75" x 1.5"

U1 is the propeller, U2 is FT232RL, U4 is 128KB eeprom.

[noparse][[/noparse]edit] See further down for updated pictures.

Bean.
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“The United States is a nation of laws -· poorly written and randomly enforced.” - Frank Zappa

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Post Edited (Bean (Hitt Consulting)) : 6/25/2007 8:45:18 PM GMT

Mike Green

Bean,
It's a great idea although I would prefer to see more I/O pins available. It's a Prop version of a BS1USB.

Phil Pilgrim (PhiPi)

Bean,

I've got a similar module (MoBoProp) in proto form. It's 2.75" x 1.35", can be powered from the USB port, and accepts Parallax's standard daughterboards (including the PropCAM). The photo shows it alongside the Parallax Proto-DB prototyping daughterboard. I need to make a couple changes, though. The A/V connector (a 3/32" stereo phone jack) has not proven itself to my satisfaction, nor has the A/D converter section.

But the fact that you're thinking along similar lines tells me the basic concept is sound!

-Phil

Mike Green

Phil,
I like yours too and it may be more versatile for the sort of things I have in mind. The Proto-DB is cheap enough for building temporary projects. I do like the idea of having more I/O (including A/V) available. Do you include a Prop A/D converter? Those really have to be planned in because of the noise and lead length issues.
Mike

Phil Pilgrim (PhiPi)

Mike,

Thanks! Yes, there's a Prop-based A/D section (lower-right corner of the board), capable of two channels for each daughterboard. It was designed in before the advantage of balanced caps was demonstrated, so it only has caps to ground. That's something I need to address in the next rev. Frankly, I'm not terribly enthused about doing A/D this way, but there just isn't room for anything else...

-Phil

Bean

Phil,
I like you idea of having daughter boards.

I haven't heard about the "balanced caps" method. Where is it posted ?

I wanted something cheap and simple, I was going to put more I/Os on the other side, but I was afraid it was getting too big. I want to use it like a memory stick. Just plug the board into a USB port on the front of my computer.

I'm making these mainly to use-up the parts I bought for the overlay board. Plus I want to get some experience with the FTDI chips. Most likely I'll make everything freely available on the forum (expresspcb layout, parts list, etc.).

I hope that's not stepping on you're toes Phil ? Let me know if it is, I'll just keep it to myself.

Bean.

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“The United States is a nation of laws -· poorly written and randomly enforced.” - Frank Zappa

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Post Edited (Bean (Hitt Consulting)) : 6/1/2007 6:42:43 PM GMT

Phil Pilgrim (PhiPi)

Bean,

You can see these caps in the schematic of the Propeller Demo Board Kit. They're in the microphone input circuit: two 1nF caps, one to Vdd, the other to ground (rather than just one to ground). This is done to make the A/D input more resistant to noise on the 3.3V supply rails.

And don't worry about my toes! The more choices people have, the better!

-Phil

rokicki

I'd love one of these for simple prop development. A lot of times I want to try something out
but I don't want to drag down all the little pieces (cables, wall wart, demo board); it would be
nice just to keep one of these in my backpack and shove it into whatever USB port is available.

-tom

mynet43

Is there enough power/space to include an MCP3208 on the board?

That would give you 8 adc ports with only 3 propeller pins in a small form factor.

There's already code for it and it doesn't have the other problems.

Tracy Allen

Same here. I'd want something really simple and inconspicuous that I could use in an airplane or something like that. Not to test out a hardware interface, but more to test out things like math routines that could be verified through the serial interface to the Mac. I might even cut off most of Bean's prototyping area, except for two or three rows for leds or a header.

I like TI's EZ430-F2013 development board for the MSP-430. $20 and it looks like a USB memory stick.

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Tracy Allen
www.emesystems.com

rokicki

Yeah, I think a single LED (or maybe a "power" and "user" LED) and a small header area (just holes; people can solder on pins if they want)
would be ideal. The smaller, simpler, and cheaper the better. Indeed if these could be made cheap enough, they would give people another
*easy* way into the prop; get one of these now and they'll quickly want to move up to the Demo board, but this will give them a taste without
requiring them to build anything. And in general, once they've had a taste of the prop, they'll want more very quickly.

Tracy Allen

Another wild characteristic of the prop is that you can load one cog with a virtual peripheral that can be the testbed for something you are working on in another cog. It may be just a matter of looping back from one pin to another. Kind of like Phil talked about with the encoder emulator.

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Tracy Allen
www.emesystems.com

Timothy D. Swieter

I also like the idea of a Prop/USB memory stick size device.· I have one of TIs MSP430 that Tracy mentioned and love it.· I like being able to test code while I was working through some C tutorials and learning about the MSP430 line of micros.· A similar device for the Prop would find good uses in my tool box.

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Timothy D. Swieter
tdswieter.com

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One little spark is all it takes for an idea to explode

hkimball

I agree that a usb prop like stick would be a very useful tool.· I am in three or 4 different places doing development any given day and it would be nice to be just carry a stick around to test code like string and math routines and send the output back through the usb port to a terminal window if possible.· I would definitley buy a couple of usb style props.

Bean

Thanks everyone, it looks like there IS interest. So I'll keep working on the design.

I'll keep everyone informed in this thread.

Bean.

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“The United States is a nation of laws -· poorly written and randomly enforced.” - Frank Zappa

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Graham Stabler

Bean,

Initial reaction was, I like that but what the heck would I use it for? Answer, testing/developing code anytime any place especially with the prop terminal so you don't need a TV with you. For me the smaller the better.

Graham

Bill Henning

Very cute!

Seems ashame not to bring the other I/O pins out though...

Bean (Hitt Consulting) said...
I got this idea to make a Prop Dongle. A very small propeller development board that plugs right into a USB port (or you could use a USB extension cable) and is powered by the USB, has 12 I/Os and a small prototype area.


I will probably build some for myself, but was wondering what you guys think of it. Too small ? Too large ?



It is 2.75" x 1.5"



U1 is the propeller, U2 is FT232RL, U4 is 128KB eeprom.



Bean.

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www.mikronauts.com - a new blog about microcontrollers

John Abshier

I think there is definite use for a small Propeller board. Bean, I do think that your board needs mounting holes.

Bean

Okay I've done some more work on the board.

You can cut off the prototype area (making it 1.5" x 1.5"), added two LEDs, reset circuit, connected more of the layout.

John, since this is meant to be used by plugging directly into the USB port on a PC, I doubt I will put mounting holes on it. I really don't have the room anyway.

As always comments welcome, this will become YOUR toy when I'm done.

Bean.




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“The United States is a nation of laws -· poorly written and randomly enforced.” - Frank Zappa

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Post Edited (Bean (Hitt Consulting)) : 6/2/2007 7:46:42 PM GMT

Forrest

Do you have a case in mind that this board would fit into? If not, can you make some minor adjustments for it to fit inside a Serpac Model 110-I case? Electroniic Goldmine sells this case for $1.99 in black. Your current board would almost fit, but you would need to change the board width around the USB connector to clear the mounting boss in the Serpac case - the USB board connector end would need to be 1 inch wide .

www.serpac.com/products_s-110-i.htm

Graham Stabler

I would have thought heatshrink would have been a more suitable case for a dongle like this, you won't be able to plug it into a PC if there are other things plugged in at the same time otherwise.

Simple folded cases are good too, see attached (not mine) and if you want to make a really fancy one check out this cool software:

www.tamasoft.co.jp/pepakura-en/

The gallery is well worth a look at.

If you really want a proper box I suspect you are looking for product built for a different design brief, possibly more like Phil's unit.

Graham

Graham Stabler

One other suggestion might be 0603 leds on any unused IO so you have some thing to play with if nothing else.

Graham

Max Wooden

I think the perfect case for this would be an altoids tin! This sounds like a really good idea, I would definitly use one.

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Max Wooden

Graham Stabler

TicTacs surely? [noparse]:)[/noparse]

Graham

Dennis Ferron

I set aside some parts to make an Atmel "dev board" inside an altoids tin. The idea is that you would open it up and have the Atmega 8 on one side and a tiny breadboard on the other (same breadboard as is on the Basic Stamp Board of Education). I planned to put a small LCD inside the lid, or on the lid. Looks like this board would be good for the same thing with a Propeller.

Bean

Here is what I'm getting for prototype boards. After I check them out, I'll order "real" boards.
Please let me know if you see anything not connected correctly. (Sorry I don't have schematic yet, I Know, I know bad form).

[noparse][[/noparse]edit] see further down for updated pictures.

Bean.
·

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“The United States is a nation of laws -· poorly written and randomly enforced.” - Frank Zappa

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www.hittconsulting.com


Post Edited (Bean (Hitt Consulting)) : 6/4/2007 4:32:47 PM GMT

Forrest

I think you need to beef-up the ground connection in the breadboard area - the top side circuit is isolated and only connected thru 1 ground hole.

Graham Stabler

I like the way you have added more io on the back of the board, could you add even more if you put the through holes under the propeller? I realise you could only surface mount wires to those holes but it might still be handy on occasion. You could even add space for optional TV resisitors on the back.

Graham

Bean

Thanks for the comments guys.
Here is an updated layout.
I added a 2-pin header for the TV output.
Only one LED on-board.
Added vias for pins 16-19

Bean.


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Graham Stabler

Looks super!

If the vias could via into slightly larger pads that would be even better if its possible.

Graham

Bean

Holy cow it works !!!!
I think this is the first time a circuit worked the first time.
Forgive my hack-job with the paper cutter.

Only thing is the TV out doesn't have any color ???
Now I used a 220 ohm, 470 ohm, and 1K ohm for the resistors. Do you think that is causing it ?

Graham,
Would you like to play with...I mean test, one of these prototypes ? If so I'll send you one.

Bean.

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“The United States is a nation of laws -· poorly written and randomly enforced.” - Frank Zappa

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Post Edited (Bean (Hitt Consulting)) : 6/8/2007 1:14:26 AM GMT