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pedward
03-30-2012, 03:23 AM
If 'PropKey' isn't already taken, I was thinking of calling it that.

Yeah, that's a 300-mil DIP reset button, I've got like 29,000 of them. The LED is a 5mm bi-color unit, just what I had. The FT232RL and EEPROM are on the bottom. It runs off USB and plugs right into the port. 28 I/O pins are brought out, as is Vusb, Vdd, and Gnd. The FT232RL supplies a 6Mhz clock to the XI pin and also supplies 50ma for the chip.

I intend for this to be a key FOB kinda toy, for writing code and perhaps some light hacking. I have a couple more ideas, but it will take a PnP machine to make it economical.

My intention is to sell these or get them manufactured by somone else. I'm still thinking of putting a uSD connector on it, on the bottom side.

For "production" the M44 variant would be more appropriate because it leaves a lot more routing space, and of course an SMD reset and SMD leds.

EDIT: So here is the latest go at this idea, on the end is a Molex Micro SD socket. It's a card edge style, very compact.

The Micro SD socket is on P16-P19, I purposely left the P0-P15 contiguous on the one side of the key.

EDIT: Yet more changes. I took an inventory of components on hand and what I needed to order, changed a package and adjusted the layout slightly. I also replaced the slot with a hole, which will be easier
to make and more robust if it is actually hung from a keychain or lanyard.

The MicroSD socket is the small rectangle with the odd pads on the bottom side. The uSD card should extend over the end of the PropKey a little, so it's easy to grasp and remove.

I haven't wired the card detect pin, and I chose to wire the socket for standard SPI mode and not QSPI, to reduce pin usage.

This is the final revision I think, before I send the design off to have some prototype boards made. Turnaround should be 2 weeks.

I won't have any pricing available for a kit format until a later date. I may also sell bare boards if there is a demand.

EDIT: Here is the latest and greatest revision. The major difference is the addition of a crystal and adjustment of the power trace width.

I read about the caveats associated with the clock generator on the FT232, my main concern was poor stability, since the common use case for this board is in a USB socket.

I think I've beat the design to death and I'm ready to send it off to have a few boards made.

EDIT: This *is* the final design, all of the traces are routed how I want, the power traces are beefy (considering only 50ma is possible) and the 4 pin header is on .100 centers to the main 32 pin layout. I also added more labelling to the bottom, though many of the numbers are obscured by parts, between the top and bottom each pin is clearly labeled.

http://forums.parallax.com/attachment.php?attachmentid=91367&d=1333589322
http://forums.parallax.com/attachment.php?attachmentid=91368&d=1333589339

GordonMcComb
03-30-2012, 03:34 AM
For those of you considering these Prop sticklets, you might think about a variation that uses a DIP socket EEPROM chip. Why? Consider outlets like MakerShed, where they like to build up kits of the articles they do in the magazine. People could buy the stick, unprogrammed, then add in the pre-programmed EEPROM (not everyone wants to do the programming, and it's FAR cheaper to inventory EEPROMs than full microcontrollers). The same stick could also be used in other projects, simply by swapping out the EEPROM. The Propeller is unique in this regard, so we might as well take advantage of it. Right?

If there were such a product available, at a reasonable price point, I bet you'd see more articles using the Prop. I know I'd be able to pitch several, and I think there would be a built-in sales channel for the half-DIY crowd -- folks wanting to build, but not yet ready to jump in quite yet with both feet.

-- Gordon

Tubular
03-30-2012, 03:48 AM
Nice work Pedward! One way or another, we really must have usb prop sticks, this year...
I reckon that would fit in one of the usb cases Jazzed and I have discussed (Bud enclosures or New Age Enclosures)

@Gordon
The thing about uSD cards is that they can be "programmed" just by a laptop, or at worst a usb card reader from any computer store, using routines already present in the operating system (right click and "send to"). I'd argue that speaks to a wider crowd than those who can program I2C memories.

Having said that, I personally like the expansion possibilities of DIP8, and the possibilties of "autoscanning" i2c addresses to see what peripherals are attached. We already have Raymans 3AD accelerometer and Vanmunch's gyro. A RTC should be possible and with the new FTDI 'X' chips, I2C<>USB seems possible too.

pedward
03-31-2012, 03:50 AM
Hey, would anyone be interested in one of these as a kit? I have all of the SMD components on hand, reels of them. I could put together kits or sell bare boards, I figure most people would want a finished board or a kit, not a bare PCB. I am also thinking of adding a micro SD socket to the board, Molex has a very compact socket that would be easier to add.

The Prop is a .8mm pitch and the FT232RL is .65mm pitch, the passives are SOT-23, 0603, 0805, and 1208. The reset button is a nice tactile momentary PTH device. The soldering does present a challenge, but not a huge challenge.

EDIT: removed shots and put new ones at top.

GordonMcComb
03-31-2012, 05:28 AM
@Gordon
The thing about uSD cards is that they can be "programmed" just by a laptop, or at worst a usb card reader from any computer store, using routines already present in the operating system (right click and "send to"). I'd argue that speaks to a wider crowd than those who can program I2C memories.

Not what I'm talking about. The EEPROM is shipped to the customer pre-programmed. Two scenarios to consider:

Scenario 1: A mail order company stocks unprogrammed controller boards, useful for a number of kits. A customer buys a kit that has a certain functionality, and the mail order company drops in the appropriate pre-programmed EEPROM chip.

Scenario 2: A customer already has a controller board, and now wants to try it in a different kit. He or she orders the parts-only kit (no controller board this time -- saves them money), which comes with a pre-programmed 8-pin EEPROM. They pull out the old chip, and insert the new. The customer doesn't program anything.

Despite their ease of use, SD and uSD cards are more expensive than 8-pin DIPs, and card readers add to the cost of the controller board. The solution has to be as inexpensive as any other, or else why bother. (However, if there can be a reliable source of very low density uSD or SD cards that cost 40 or 50 cents in quantity, it's certainly an idea.)

The concept rests on a unique aspect of the Propeller, that its program is external. The majority of other controllers used for these types of kits all have internal flash, which means a lot of excess inventory waiting for a sale. Sellers of these ready-to-go kits may be more willing to try non-Arduino offerings if they can stock generic product that can be easily customized.

-- Gordon

StefanL38
03-31-2012, 08:48 AM
Why should plugging the board into a USB-port and using a "flashing"-software to upload new code into the EEPROM such a big problem for users or distributors?
best regards

Stefan

User Name
03-31-2012, 01:10 PM
Hey, would anyone be interested in one of these as a kit? I have all of the SMD components on hand, reels of them. I could put together kits or sell bare boards, I figure most people would want a finished board or a kit, not a bare PCB.
I'd be very interested in them as a kit. Seriously, put me down for a dozen.

Ragtop
03-31-2012, 01:49 PM
Would be an interesting pairing with an xbee.

Rayman
03-31-2012, 02:51 PM
This looks great! You might consider the FT231X instead of FT232RL though to be smaller and cost less...

pedward
03-31-2012, 07:46 PM
This looks great! You might consider the FT201X instead of FT232RL though to be smaller and cost less...

The FT201X series doesn't have DTR, so you can't do reset. I consider this a big omission, or did I miss something?

jazzed
03-31-2012, 07:49 PM
The FT201X series doesn't have DTR, so you can't do reset. I consider this a big omission, or did I miss something?

Apparently RTS reset is supported in the latest Propeller Tool. I'm also adding it to SimpleIDE.

Rayman
03-31-2012, 07:53 PM
Sorry, I meant to say FT231X. It does have DTR. FT230X is even cheaper, but it doesn't have DTR...

pedward
03-31-2012, 10:38 PM
I have revised the design to remove the bi-color LED and put a single TX/RX LED near the USB connector. This is to make space for a micro SD socket. Molex has a nice, compact, socket here: http://search.digikey.com/us/en/products/0473093751/WM3974CT-ND/2421666
The socket is about 5mm deep, which makes it easy to put towards the end of the board, without taking up too much space.

For people that are interested in kits, would you like a *complete* parts kit, or would you like to source some parts locally?

I've got a neat idea of how to provide a kit while making it very obvious which parts are what and to do a quick QA so no parts are left out.

User Name
03-31-2012, 11:57 PM
For people that are interested in kits, would you like a *complete* parts kit, or would you like to source some parts locally?
Speaking just for myself, I've got SMD Props, LEDs, thru-hole switches, and a broad selection of SMD passives. But I'd be interested in having the other ICs supplied as well as a socket for the micro SD - particularly if you were ordering some anyway.

pedward
04-01-2012, 02:37 AM
I added the latest revision to the top post, it has a micro SD socket and I moved to a single SMD LED for USB activity.

I tried to make the layout spacious so that it could be soldered by hand and I haven't used any parts smaller than 0603. I made the pads for the SB socket bigger so they had some space to wick solder up from.

Duane Degn
04-01-2012, 04:31 AM
Speaking just for myself, I've got SMD Props, LEDs, thru-hole switches, and a broad selection of SMD passives. But I'd be interested in having the other ICs supplied as well as a socket for the micro SD - particularly if you were ordering some anyway.

I'm in the same boat as User Name as far as parts are concerned.

Depending on what you end up selling these for, I may be interested in a couple.

Bean
04-01-2012, 02:52 PM
Is the large rectange on the end a cut-out ? If so you will have to radius the inside corners (I'd recommend 1mm).
Inside routing is usually expensive. I'd recommend doing a 4 or 5 large holes instead.

Bean

pedward
04-01-2012, 11:29 PM
I have posted the final design in the top message, unless there is some compelling reason, this version will be sent off tomorrow for a prototype run.

jazzed
04-01-2012, 11:40 PM
How thick is your board?

pedward
04-02-2012, 12:00 AM
How thick is your board?

63 mils is what I'm prototyping with, but I measured a USB connector at .079. I was thinking that a creative way to resolve this is to get some thick plastic adhesive sheeting and adhere it to the back side of the USB connector end. This would make up the difference in thickness without costing a lot extra. I don't do a lot of PCBs, so I'm going through DorbotPDX to get these made, and like most, .063 is the standard. I think the shim idea is solid and innovative, which will keep prices down. I'd bet that it would be completely infeasible to offer these if I had to get .080 thick boards made up.

EDIT: I checked McMaster carr and they have .022 thick UHMW adhesive tape. This is perfect for the shim, since UHMW is very durable stuff and it will not abrade from being inserted. I tested a board here with some scotch tape and .022 is exactly the perfect thickness over the base to get a snug fit in USB ports.

User Name
04-02-2012, 12:57 AM
Looks great! Phenomenal cosmic power in an itty-bitty living space.

Edit: I've got second thoughts about the kitting. If you've already got rolls and rolls of the right passives, perhaps you should include passive devices in the kits. Kludging a 1208 part into a 0603 footprint isn't worth saving a few pennies on the kit price.

Perhaps the only kitting option that makes sense is to offer them with or without Prop.

pedward
04-03-2012, 06:22 AM
Based on the discussion in the GGUSB thread, I reworked the layout to bring p28-p31 out to and added a header for p16-p19 below the uSD socket.

Honestly, the first layout without p28-p31 is cleaner than the revised layout. I also don't see much point in exposing the pins, since it's intended to plug directly into a USB port.

Please review the two layouts and give your thoughts.

Tubular
04-03-2012, 06:44 AM
I think the benefit of having *all* pins broken out outweighs the very slightly less clean layout (it doesn't look much less clean anyway)

While it's designed to plug into a USB port, end users may want to run it from a mains-to-usb plug pack, in which case powering from 1 source and programming from a second (prop plug) is advantageous.

You gain a second version of the board that can be programmed using a prop plug, saving the cost of the ftdi.

Finally, I2C (P28/29) is useful if you want to add an RTC (since you've got a uSD there already).

jazzed
04-03-2012, 06:49 AM
Based on the discussion in the GGUSB thread, I reworked the layout to bring p28-p31 out to and added a header for p16-p19 below the uSD socket.

Honestly, the first layout without p28-p31 is cleaner than the revised layout. I also don't see much point in exposing the pins, since it's intended to plug directly into a USB port.

Please review the two layouts and give your thoughts.

Here's what I did. http://forums.parallax.com/showthread.php?134602-Propeller-USB-Key I plan to re-spin it with the SSOP16 FTDI chip.

Tubular
04-03-2012, 07:09 AM
@pedward, two other things I noticed
- the hole in the corner might be obscured by the uSD card when installed in the molex socket. Hard to tell without a line to see where the extent of the card ends.
- I reckon your design is a good chance of fitting in a ready made usb enclosure. However it may be a good idea to keep tracks as far as possible away from the 'shoulders' in case you need to file away some of the pcb to make your usb connector deep enough. eg the track that passes outside P0/P1 may be better to route in between P0/P1, and there is another track just outside the FTDI that may go inside the FTDI outline instead.

@jazzed,
The FT231X may be a better option as it has DTR for full compatibility. Its about 8c more in 100 off qtys, ie half the price of FT232RL. I only used the FT230X because I really couldn't spare the extra 1.3mm, however I will change to the FT231X when it goes on the other side.

pedward
04-03-2012, 10:47 AM
Tubular, I tweaked the layout a little and tidied up all the traces and vias. The uSD card does interfere with the hole, but if a small lanyard is used, it shouldn't be a problem. There wasn't enough space to move the socket over. The board is 18.5mm wide and ~53mm long, to the shoulder near the USB connector. It's ~64mm long with the USB connector. That works out to 2.08 inches by .728 inches, which is just shy of 3/4 wide.

I'm satisfied with the layout and will probably send the board off tomorrow.

Sapieha
04-03-2012, 12:40 PM
Hi pedward.

Before You send it for production increase Power traces at least to dual thickness.

16 else more mil's


Tubular, I tweaked the layout a little and tidied up all the traces and vias. The uSD card does interfere with the hole, but if a small lanyard is used, it shouldn't be a problem. There wasn't enough space to move the socket over. The board is 18.5mm wide and ~53mm long, to the shoulder near the USB connector. It's ~64mm long with the USB connector. That works out to 2.08 inches by .728 inches, which is just shy of 3/4 wide.

I'm satisfied with the layout and will probably send the board off tomorrow.

pedward
04-04-2012, 02:09 AM
The top post has an updated layout, thicker power traces and a can crystal instead of the FT232 generating the clock.

Tubular
04-04-2012, 02:20 AM
Looking good.

The FT232 can't generate the clock output until USB enumeration is complete. Ok so maybe that isn't as big a deal for your design that will mostly run plugged into a PC.

A few of us have been down that path at one stage or other to try to save an xtal. Separate xtal like you have now is a good idea

Cluso99
04-04-2012, 02:20 AM
Looking good. Just increase the power and ground traces as mentioned by Sapieha.

May I suggest you also add two extra pins in the P16-19, being 5V (or 3V3) and GND in the sequence V,GND,16,17,18,19. Why? Then your PropKey can look like a propplug to another prop board, and you can also supply 5V or 3V3 to this board. I have chosen to supply 5V and put cheap regulators on each of my modules.

If you do this, will the SD card interfere with these pins? If so, you could put them on the underside. I have 1x14 RA female (can be cut down) and 1x6 ST female (can be bent) if you require some.

Presume you are using DorkBox - you can put an overlay on the underside too! I suggest you label the I/O pins on the underside.

pedward
04-05-2012, 02:34 AM
The top post contains the *final* final layout, with consideration given to all of the comments and work that has come before. It's jam packed with parts, traces, and labels.

I'll probably send it off tomorrow, since all of the things that were in the back of my head are resolved and done.

I'm thinking that I'll offer a passives kit and full kit to start. I may even offer a hybrid kit that is partially assembled, with the hard parts mounted.

pedward
04-06-2012, 01:30 AM
Hi everyone, I made the effort to create a Digikey kit of all the components used in the PropKey. I thought this would be useful for transparency and order fulfilment if people just want bare PCBs. I have attached the BOM I created. Unfortunately Digikey's interface makes you think that the 'kit' you create is an actual Digikey P/N, but it's not!

This sort of makes things easy for people because if they want 1 or 10, they can choose and tweak quantities to find the sweet spot for themselves.

I have all of the passives on hand, and the switches, which amount to about $2.50 of the total cost (in kit quantity). The total for the BOM is $18.91.

John_Allen_Stl
04-08-2012, 12:24 AM
Looks fine to me..! I got a project started on the QuickStart board to gather up engine temps, Rpm ect.. and this little guy would work well on a vector buildup..

Kit-em up, and what would you need for a couple copies.. ?

Thanks !

pedward
04-09-2012, 12:31 AM
The design is going out Monday to the board house, I should have 3 protos back in a couple weeks. Once I've worked out the details I'll post the kit cost. Kits will consist of a complete Digikey labeled bag of parts and a PCB, plus some instructions and part layout labelling.

pedward
04-26-2012, 05:14 AM
I finally got the PropKey working and have a final layout figured out. The LED is a biggun and will suck down 20ma, which causes the FT232 to be disrupted. I changed the current limiting resistor to 1K and that fixed it.

The whole Prop side of the board worked fine from the get-go, I was just having USB problems. It runs at 96Mhz (because the cylindrical crystals were easy to find in 6Mhz) and the SD card interface works peachy.

I have included pics of the prototype board, now I have to send the Gerbers out for another board spin. The little board really *IS* cool to hold in your hand!

The overall size is about the same as a DIP-40 with a USB connector on the end.

http://forums.parallax.com/attachment.php?attachmentid=91990&d=1335413562
http://forums.parallax.com/attachment.php?attachmentid=91991&d=1335413571

Duane Degn
04-26-2012, 07:39 AM
That looks really cool!

That uSD socket looks like the same part Tubular uses on his Und3rb3lly board.

Tubular was nice enough to give a couple of his little boards (he doesn't sell them but he'll give them away?) and I had a hard time soldering the uSD socket. I did get it soldered, but I thought it was a lot harder to solder than the smt Prop chip.

I'm not suggesting you use a different socket, I'm just giving my opinion/warning. I think the socket is a good match for this board, I just wish they were easier to solder.

Do you have pull-up resistors on both the data and clock I2C lines? I know some of the I2C objects require pull-up resistors on both lines.

I look forward to seeing what these will cost. (I see the BOM in post #32, but it looks like you still don't know what the PCB will cost.)

Once again, these look really great!

pedward
04-26-2012, 07:53 AM
I think the socket is the same one Tubular is using. I actually reflowed the socket and that side of the board using my hot plate and some paste. It was really easy and quick, surprisingly. The little .8mm pads were a pain, but not really necessary since they aren't connected.

The uSD and I2C both have 10k pullups, so those are compliant.

Wish I hadn't gotten the pad layout backwards for USB on the prototypes ;)

Tubular
04-26-2012, 08:12 AM
Those "uSD headers" are the same, and they come in about 4 different heights. The "375" variant is 3.75mm high and the easiest to solder by running a soldering iron tip across with plenty of flux present underneath. I can't remember which height I sent you Duane as I use 2.65 and 3.75. They aren't as bad as they look once you get the hang. I think in future I'll just solder the socket onto the pcb before sending out.

I checked Pedward's BOM when he posted it, and he had the 3.75mm part listed, but sounds like he's fine with reflow in any case.

Nice work Perry, sure it won't take long to correct the usb footprint. Aren't you thankful the protos are as cheap as they are. I think Laen deserves a knighthood. Certainly many beers.

Cluso99
04-26-2012, 08:53 AM
Congratulations. Nice and small ;)

pedward
04-26-2012, 09:06 PM
Here is a comparison in size between the Quickstart and the PropKey:

http://forums.parallax.com/attachment.php?attachmentid=92005&d=1335470753

pedward
04-28-2012, 12:49 AM
The Propkey RC1 is off to the board house on Monday. I'm hoping to get the protos back before May 14th so I can build and test one before I commit to a medium run (~75). I haven't figured out the costs quite yet, I'm thinking about selling assembled units.

My concerns are this: I think the ideal price for the PropKey is around $40 assembled. For someone who has a proper manufacturing line I think that is a price that can make a profit. I don't want to introduce these at a price that would effectively undercut any future opportunities like this.

Assembling kits doesn't require a lot of technical expertise, but it's tedious and time consuming trimming parts off of reels and tracking them. Digikey offers a kitting service at a premium, then you get bagged and labeled parts. I already have many of the passives on hand, so only a small number of parts would be sourced from Digikey, which makes having them kit up the parts somewhat ineffective.

Below is a picture of the Gerbers from GerbV:

http://forums.parallax.com/attachment.php?attachmentid=92063&d=1335570567

pedward
04-29-2012, 02:15 AM
I designed a breakout board that can be used to interface with the PropKEY.

Here's a first cut at the design:

http://forums.parallax.com/attachment.php?attachmentid=92083&d=1335662132

Duane Degn
04-29-2012, 08:27 AM
Perry,

I would have thought, you'd want the holes for P0 and VUSB near the top edge of the board so the USB connection could still be used while the PropKey is attached to the breakout board.

I'm I missing something?

pedward
04-29-2012, 08:55 AM
The PropKey board sits far enough off the board (with headers) to use a USB extension cable. I wouldn't expect anyone to connect a 2.5x2.5 inch board to something hanging out their USB port.

I could come up with a smaller board that is just a small header extension board, but it wouldn't have any prototype area.

Tubular
04-29-2012, 09:44 AM
I think it would be good to have some power (Gnd and 3v3) holes somewhere near the outer four corners. Also there is room for some more holes for P16..19. P16 and P17 could "run" to the left and P18..19 towards the right

pedward
04-30-2012, 12:05 AM
I think it would be good to have some power (Gnd and 3v3) holes somewhere near the outer four corners. Also there is room for some more holes for P16..19. P16 and P17 could "run" to the left and P18..19 towards the right

I may have to do a little cheating to add more, I'm at 299 "pins" right now.

pedward
04-30-2012, 12:08 AM
I downloaded the PropGCC SimpleIDE and played with it today. I have attached a config file which can be used with the PropKey to program and communicate with it. I have enumerated the SD card pins in the config file so an SD loader can be used. The PropKey has a 64K EEPROM, like the quickstart, etc, so XMMC can be used with that too.

I copied and adjusted the PPUSB config file, since it is very similar, I hope I got the settings configured right.

For the IDE to recognize the new file, put it in c:\propgcc\propeller-load and hit the puzzle piece icon next to the board list in SIDE.

Tubular
04-30-2012, 12:36 AM
I may have to do a little cheating to add more, I'm at 299 "pins" right now.

Lol yes so you are. I think you could do one long 'Gnd bar' the full length along the left hand edge, and possibly the right hand edge. I think you could steal some holes from the "res" line as its unlikely to need many connections if any

pedward
05-03-2012, 08:31 AM
Here are some renderings of a FLASH/RAM board I designed for the PropKey. Jazzed was interested in something like this for PropGCC.

What I've got is 16MB of qSPI flash and 256KB of SPI RAM.

The flash is on P0-P7 and enabled on P26. The RAM is on P0-P7 and enabled on P25. P27 is the serial clock.

The RAM chips are the same part used on the C3 and the flash chips are the Winbond devices that are already supported in PropGCC.

This *should* be the ultimate fastest XMM solution so far.
http://forums.parallax.com/attachment.php?attachmentid=92184&d=1336030197
http://forums.parallax.com/attachment.php?attachmentid=92183&d=1336030197

jazzed
05-03-2012, 05:27 PM
The flash is on P0-P7 and enabled on P26. The RAM is on P0-P7 and enabled on P25. P27 is the serial clock.
The CS and CLK pins could be easily changed with a new driver.

One option is to use P28 for the clock and P26,27 for chip selects. As long as P29 is held high the activity on P28 doesn't matter for GCC. You probably want the hardware to be adoptable by other compiler solutions too, so a wasted pin might be worth it.


The RAM chips are the same part used on the C3 and the flash chips are the Winbond devices that are already supported in PropGCC.
You'll need a pull-up on the CS* line for Winbond QuadSPI chips - see pin notes. I'm worried about higher density part SOIC-8 availability though. Higher density QSON seems more available than SOIC-8 and at minimum they will require no vias under the chip body. Preferably QSON should follow that footprint of course.

The SST SQI parts can also be used with another driver, but our experience so far is that they are not fully single-bit SPI compatible (being fully SPI compatible would be an advantage on P2 for inventory purposes). They are faster than Winbond chips for quad mode address setup, but they are more expensive and don't seem to be readily available in the US.

Some hardware critique if you don't mind: Considering power supply configuration you probably need a few more decoupling caps for the SPI-SRAM and possibly a 10uf low ESR bulk capacitor for both boards. Some folks may insist on series dampening resistor options for the SRAM IO, but the traces aren't really long enough for that - unless the pins get shared. SPI-SRAM is available in 64KByte sizes too for a 512KB solution.


This *should* be the ultimate fastest XMM solution so far.

I'm sure that's arguable, and we will never get any agreement on that argument because of personalities :)
I would call it one of the fastest "XMMC" code cached solutions and faster than code + data XMM solutions.

DR_ACULA's counter clocked SRAM probably will be faster than byte-wide QuadSPI Flash and other designs, but that eats lots of real-estate. It also takes a huge number of "dedicated" pins - he is working on an interesting pin group mechanism that may mitigate the number of pins required.

Thanks for sharing,
--Steve

pedward
05-03-2012, 06:34 PM
To clarify, this is 1 board, top and bottom. The Flash and RAM share the data pins with alternate chip selects.

The 8 pin SOICs are back in stock and it appears that Digikey doesn't maintain more than 100 of any package.

I originally designed it with the 16 pin part, but their pin choices were too goofy to do a clean layout.

I also originally had 1 cap per RAM chip, but that added to the layout space, then I switched to TSSOP to get more clearance. I will go back and add caps now I've got the placement pretty well sorted out. I'll also add another 10uf cap and a 10k bias resistor to the chip selects.

Could you elaborate on the series resistors?

jazzed
05-03-2012, 07:16 PM
Could you elaborate on the series resistors?


Overshoot dampening for long term reliability and noise suppression.
They can also be useful when multiple outputs accidently drive one node - but no one ever lets that happen :)

pedward
05-04-2012, 06:37 AM
I added pullups and additional caps. The 8 SPI RAM chips share 5 .1uf caps that are equally spaced to serve the chips. There is a 10uf tant near the main power pins. I put 10k pullups on the /CS for the flash and RAM.

I did not put series resistors on the data lines (space constraints with current routing), but I did try to ensure the routes were sane (as opposed to the insane routing that the AR generates from time to time).

pedward
05-04-2012, 06:39 AM
BTW, do you have a part number for a 64K SPI RAM chip? I couldn't find such a beast, that didn't cost $11 (because it was the cypress "quantum trap" NVSRAM).

HFS, the Ramtron 2Mbit FRAM chips are $22 each!!! On what planet are they smoking?

jazzed
05-04-2012, 06:56 AM
Send email to Heinz at IPSiLog for 64KB SPI SRAM. His prices are competitive.
http://www.ipsilog.com/content/index.php

pedward
05-04-2012, 09:55 AM
After an email with Heinz, I revisited the design *again* and now have decoupling caps on every chip, very near the VCC. It was tricky, but I managed to place and rout it.

A quote from Heinz is pending, so I'll have a better idea what it will cost me to build the memory boards.

The final tally looks like 16MB of qSPI flash on P0-P7 (I realize you put it on those pins to avoid an extra bit shift) and potentially 512KB of RAM on P0-P7.

This would facilitate DMA transfers from flash to RAM, or any other device on those pins, ala Drac's memory setup. But instead of needing a bunch of external shift registers, the SPI chips handle that for you.

HMM, now I'm wondering if I should route the HOLD pins so you can do setup, HOLD, then resume?

Well, I got /HOLD routed for the SRAM chips, so now everything should be happy.

pedward
05-25-2012, 12:02 AM
Hello everyone!

I got quotes back from an assembler to build the PropKey.

The cost to produce a quantity 25 run of these would be approximately $59 each, that's COST!

The cost to produce them in quantity 100 is approximately $34 each.

I'll be honest, I don't have the capital resources to order 100 of these.

I'm considering another approach or 2, building them in small volume at home, or providing a semi-built kit, which has the fine pitch parts already soldered, and leaves the remaining components for the recipient to solder.

My originally projected price was $40, but after getting quotes, clearly that's cutting it very thin.

It was always my intention to get Parallax interested in producing these as a vector for Propeller adoption, but they have too much on their plate right now.

I'm open to comments and suggestions, I don't want to just drop this because of some shorter term logistical issues.

If I produce/sell boards/kits, I can get the bare board for a very reasonable price via Dorkbot PDX, about half the price of the vendor I contacted.

The BOM is still around $16 in quantity 10, and I have almost all of the passives on hand, I would have to order the semiconductors (which are the bulk of the BOM).

Ken Gracey
05-25-2012, 12:15 AM
@oedward, I'm not at all surprised by these costs. This is why we don't get involved in anything unless we can build 500-1,000 units minimum.

Our first run Propeller BOE costs exceeded $85, and that doesn't include any design/layout/prototyping NRE (that's production only). Building products in the USA is very expensive - period. The only way you can get around this is to build in volume, and often build it yourself (without contractors).

I also want to see PropKey come to production, but I realize the challenges of production are significant in terms of labor.

Ken Gracey

Cluso99
05-25-2012, 01:36 AM
pedward: Welcome to the real world. Setup costs for a manufacturer are huge, and that has to be amortised. I was a partner in a contract manufacturing plant here in Oz a while back. You really see what goes into even just quoting to build an item.

DorkBot is great for tiny boards in low volumes because the overheads are amortised over a huge pcb. However, larger boards are expensive. So too are pcbs in quantities. I suggest you look at getting a large run of pcbs done (say 100) because then you can amortise the setup costs.

From DOrkBot your pcb is approx 2.4"x0.7"= ~1.7"sq @ $5/"sq/3 = ~$2.80 per pcb.

A pcb supplier I used (forget name atm) they make 4x7" panels for about $80 setup, $30 freight, $5 per panel. Add $20 (estimate) for ENIG
You would get 10 pcbs per panel in a 5x2 arrangement with fingers out and vgroove.
100 pcbs = $80+30+20+$50 = $180 / 100 = $1.80 which is not a great deal better considering the outlay.
They may also charge extra for the complex pcb outine routing.
The reason is that your pcbs do not fit their panel size nicely.

This is why I make rectangular shaped pcbs.

This is the reason my pcbs

jazzed
05-25-2012, 02:46 AM
Going to an assembly house incurs a setup cost. For small quantities keeping assembly within a friends and family circle is the only way to go. Even so, having components on both sides is a killer. Small, packed boards inevitably need at least passives on the bottom and that means a costly "second op." Having small boards panelized really helps.

Oldbitcollector (Jeff)
05-25-2012, 03:20 AM
This probably isn't practical, but if there is ANY WAY POSSIBLE to kit PropKey, that will be the direction to go to keep the prices within reason so that you can make enough money to pay for your time, and still have a few people interested in the product.

OBC

Ken Gracey
05-25-2012, 04:24 AM
Setup costs are the big expense. In a low-volume run, P&P programming, parts procurement and dealing with any test fixtures will easily comprise 80% of the total cost. It's necessary to have volume to spread these setup costs across a larger number of units.

If PropKey BOM is $25 and you want to build 100 units, a contract manufacturer will charge $15 labor per unit and $1200 setup cost. That works out to be $42/unit.

Even with the same setup costs, labor per unit and BOM costs, 1,000 units works out to be $31/unit.

But as Perry pointed out, you need volume to make this happen (plus a lot of cash that nobody has lying around). So what's the solution? There are at least five of them:

(a) Human P&P plus home reflow oven. Apply solder paste with dispenser. Yuck.
(b) Find a friend who agrees to run them for you. Some friend!
(c) Send it to a Chinese assembly house, telling them you're just testing their setup for larger volume with a trial run. Not necessarily ethical, but works.
(d) Design the PCB for hobby SMT assembly
(e) Place your parts manually, push them into our reflow oven between other boards.

Did I read somewhere that the PCB has parts on both sides? I hope not. . . please tell me it's not true. Dreaded 2nd op.

Ken Gracey

pedward
05-25-2012, 04:31 AM
I already priced boards through DorkbotPDX, they have a medium run service that costs $1 per sqin, which is very reasonable.

I found a desktop reflow oven on Ebay today, $264 as shipped for an 18x23.4cm reflow area. It's IR with profile control, which looks like a good solution for small volume home assembly.

I *can* kit these up relatively easily and already had an idea of how to do it efficiently and with proper QA before I even thought of selling them.

I think the right way to go is to do a partial kit, where the ICs and uSD socket are reflowed by me and I supply a passives kit for the recipient to solder.

I think I could offer them for $40 as shipped.

How does this sound?

pedward
05-25-2012, 04:42 AM
Setup costs are the big expense. In a low-volume run, P&P programming, parts procurement and dealing with any test fixtures will easily comprise 80% of the total cost. It's necessary to have volume to spread these setup costs across a larger number of units.

If PropKey BOM is $25 and you want to build 100 units, a contract manufacturer will charge $15 labor per unit and $1200 setup cost. That works out to be $42/unit.

Even with the same setup costs, labor per unit and BOM costs, 1,000 units works out to be $31/unit.

But as Perry pointed out, you need volume to make this happen (plus a lot of cash that nobody has lying around). So what's the solution? There are at least five of them:

(a) Human P&P plus home reflow oven. Apply solder paste with dispenser. Yuck.
(b) Find a friend who agrees to run them for you. Some friend!
(c) Send it to a Chinese assembly house, telling them you're just testing their setup for larger volume with a trial run. Not necessarily ethical, but works.
(d) Design the PCB for hobby SMT assembly
(e) Place your parts manually, push them into our reflow oven between other boards.

Did I read somewhere that the PCB has parts on both sides? I hope not. . . please tell me it's not true. Dreaded 2nd op.

Ken Gracey

LOL, the dreaded 2nd op!. Well, there wasn't room on the 1st side for everything, at least with the first round. I reflowed the bottom side with a hot plate (lab style, not walmart) and a thermocouple to get the proper temps. The first try worked out really well, especially because I knew I couldn't solder the uSD connector with it's pad layout.

I'm pretty ingenious, so I think I can make this work out for the main components. I have to design the process so my wife can do it at home, so there is some curve!

I had a machine shop for several years and figured out how to exploit my software programming background to make setups and "1 off" parts economical for me. The trick is in fixtures and standardization.

I'm thinking of making a board holder and plastic templates for placing the components. I can also have some paste templates made to do it "properly".

The way I see it:

*Apply paste on bottom with template
*mount board in array holder
*lay plastic template over array
*carefully place SMT parts in respective cutouts
*remove template
*reflow
*flip and apply paste to other side
*put in holder
*apply template
*place SMT parts
*remove template
*reflow
*INSPECT with microscope
*rework (if needed)

I figure 5 or 6 boards in array, laser cut polymide stencil, laser cut plastic template.

I have found that with care you can freehand place the components, as long as it doesn't take forever, this would probably work, then a simple board holder made from FR4 could be used.

Bean
05-25-2012, 12:35 PM
A year or so ago at my work some board mfg sent in a sample of a PCB that already had the solder paste on it. It was a special paste and they shipped them with plastic over the paste. You basicly peeled off the plastic and started placing parts.
I can't find it but you should be able to google them.

When I did reflow I used a hot air wand that had a large (about 1") end. It worked really well. You could see what areas hadn't reflowed yet and concentrate the heat on them. This would work even better if you had the PCB on a hot place set to about 100C.

I would suggest selling as kit, with a markup ($20 ???) to be populated. Then you can just populate them as they are ordered. There is nothing worse than populating a bunch of board and then not selling them.

Bean

pedward
05-26-2012, 12:31 AM
I communicated with the assembly house more today. The basic gist is that I am stuck at $31-33 each in q100 for the PropKey. What I'm going to do is make an order of ~75 boards with DoPDX and hand assemble those at home. I expect the pilot run to give me a good idea of the demand, then if it is enough, I'll redesign the board. On the new board I'll try to go with QFN parts and smaller passives to get everything on the top side, for easier assembly. I stayed away from the QFN parts because I wanted to be able to hand solder/assemble the boards, but if I know I'm going to have a fab house make them, I'll make it easier to build.

I've got a RAM/FLASH board that I need to send off and test, but it should work real nice with the XMM modes in PropGCC, and in SPIN/PASM if anyone wants. The tentative specs of the RAM/FLASH board are: 512KB 8xSPI SRAM, and 16MB of 2xqSPI FLASH. That's 8-bit wide flash and RAM that can be SPI controlled, including the /HOLD line on the RAM so you can setup a transfer, pause, then clock the transfer on a common bus. This would allow you to do DMA to an LCD display, or stream video data to VGA. You would setup a transfer from RAM or Flash, then run a counter at whatever dot clock you want, to stream the data out of the memory. You can also stream to an LCD this way: setup the RAM transfer, assert /HOLD, setup the LCD to receive, then de-assert /HOLD, and clock the data.

Oldbitcollector (Jeff)
05-26-2012, 05:56 AM
@pedward,

A thought.. Could you make your project as SMT friendly as possible in your design and then push it out as a kit? This might be the perfect project for someone to learn SMT soldering at home isn't as bad as they think.

OBC

pedward
05-26-2012, 06:06 AM
Jeff,

Yes, I want to offer it as a kit too. There are a couple of difficult parts to solder, I'll put those on first, then ship a kit of parts with instructions.

Once I get this rolling, I want to offer another kit that fits in an Ice Breakers mint container. The new containers are plastic, 76mm dia, and ~14mm deep. I was thinking of designing a PTH kit that has the USB chip pre-soldered, but has a USB type B vertical PTH connector, 40pin DIP, LEDs, and a small prototype area. The USB connector is about the same size as the "to share" flap, and the proto area/LEDs will be under the "not to share" flap. You could store some short wires and stuff instide the container and close the flap, easy to carry around or deploy innocuously.

Rayman
05-27-2012, 01:21 AM
I'm curious how hard 2-sided reflow actually is...

I recently tried baking a big 128-pin QFP upside down because I wanted to remove it (and didn't have the hot air gun handy).
But, the thing wouldn't come off!

Wonder now if it's really easy to do 2-sided because things on the bottom don't fall off...

pedward
05-27-2012, 01:32 AM
The major issue is running it through twice, it's like making 2 boards.

Duane Degn
05-27-2012, 03:59 AM
On the new board I'll try to go with QFN parts and smaller passives to get everything on the top side, for easier assembly. I stayed away from the QFN parts because I wanted to be able to hand solder/assemble the boards, but if I know I'm going to have a fab house make them, I'll make it easier to build.

Remember with a QFN part you can't place vias (other than to ground) under the chip. I counted (not carefully) 11 vias under the Prop on your board.

In my very limited experience, I've found QFN parts with a center pad, don't offer much of a space savings because of the lost area to place vias.

I'm sure you already know this, but I've been amazed at how difficult QFN parts are to solder compared to QFP parts.

It sounds like reflowing a second side isn't the issue I thought it would be. I had considered (with my planned double sided board) using lead free solder for the first side and then lead solder for the second. I figured the lead free shouldn't melt while the leaded side is reflowing. But it sounds like it's fine to use the same solder on both sides of the board.

Sapieha
05-27-2012, 06:51 AM
Hi Duane.

That is correct -- But with some correction. On 2 sided PCB's that is correct but on 4 layer PCB's it give much more place to spell on.


Remember with a QFN part you can't place vias (other than to ground) under the chip. I counted (not carefully) 11 vias under the Prop on your board.

In my very limited experience, I've found QFN parts with a center pad, don't offer much of a space savings because of the lost area to place vias.

I'm sure you already know this, but I've been amazed at how difficult QFN parts are to solder compared to QFP parts.

It sounds like reflowing a second side isn't the issue I thought it would be. I had considered (with my planned double sided board) using lead free solder for the first side and then lead solder for the second. I figured the lead free shouldn't melt while the leaded side is reflowing. But it sounds like it's fine to use the same solder on both sides of the board.

pedward
06-01-2012, 09:17 AM
I ordered one of those T-962 desktop reflow ovens this week. I'm going to assemble a Propkey using hand assembly when it arrives. Then I can assess any problems or redesign issues and go from there.

I'm on the fence about a redesign of the board, what I've got now, I'm 99.9% sure works fine, it's just more difficult to assemble because it's got components on 2 sides. A redesign would be aimed at putting all components on the top side, so it is a single step. To be honest, the assembly cost wasn't the largest expense of making batches of these, the components and boards were the bulk of the cost of the assembly quote.

I'm leaning towards just sticking to the known design and moving forward. I've got a memory card that I want to test, and I need a fixed target board for that.

I'll post an update once I've used the new oven. I'll probably order prototypes of the memory board when I make a medium run order for the PropKey.

Cluso99
06-01-2012, 09:42 PM
pedward: Nice. I will be interested to hear how the T-962 performs. Presume its not the larger A version. I am interested to see how smoothly the drawer works.

For double sided, they use a red IR type glue dot on the first side and reflow. This effectively glues the part to the pcb as part of the reflow procedure. Then they turn the pcb over and do the second side.

pedward
06-02-2012, 01:03 AM
Yeah, I read that they use the glue for bigger parts. I'm going to try it with just the solder holding things on.

Cluso99
06-02-2012, 01:07 AM
The glue was used for parts as small as 0604 which were the smallest at the time. It is just a tiny dot placed by the smt robot.

It should be fine without. The smt lines we used were not that vibration free - a conveyor style.

T Chap
06-02-2012, 05:14 AM
I have a few suggestions as a compromise. There are only a few passives anyway, convert to 0604 for easier tweezer placement. For the first versions, don't try to do a double sided with glue... rather sandwich two pcbs together and use headers to tie each side together. You couldn't use both top and bottom parts of the USB insert, so chop off the part of the PCB that doesn't have the traces on it for contacts. Panelize the boards in sets of around 25. Build a hand rest out of 1/2" aluminum tubes spaced out on 2" rows so that you can rest your hand over any area of the panel when placing boards. Use http://www.hitechstencils.com or other company to make a stainless stencil for the panel. Leaded solder is easier to work with at first, manncorp.com has a no clean leaded that works nice. You could crank out 25 sets in a few hours easily. If sales pick up, then maybe it will justify some outsourcing for fabrication.

Cluso99
06-02-2012, 07:09 AM
Its hard to see what is on the back of the pcb. Seems to not be much, so leave that for hand soldering. I use 0805 as they are easy to solder by hand.

John Board
06-02-2012, 08:58 AM
Hi,

Would you be able to add the avaliablity of having an external power source? Or did I miss something in the "schematics"? Is vsub the substitute power source? Other wise, I think this is great.

How much would one cost (pre-assembled... I don't know how to SMD solder)?

Kind Regards,

John

T Chap
06-02-2012, 01:33 PM
Or just make the PCB a little wider, who cares if it is slightly wider than a USB drive. 0603 is just as easy to hand solder as 0805, a lighted magnifier on a swivel arm helps.

Cluso99
06-02-2012, 11:13 PM
Actually I find the resnets easier to hand solder than the 0805 because they sit flat and dont want to tombstone. The 0805 resistors are actually fine, but the larger (as in higher) 0805 capacitors are more of a problem. I wear magnifying glasses - I got them from my jeweler brother.

pedward
06-05-2012, 07:02 AM
I received my T-962 desktop reflow oven today and assembled a double sided propkey entirely with reflow. The process was basically what I expected. I did the bottom side first, then went to the bench and populated the top side. I had an old CPU I put in the oven, pin side up, to rest the board on so it would lay flat, and I didn't have any problems with bottom side components during the second operation. Initially I thought I had a problem because BST wouldn't detect the prop, but it turned out I had minicom running in another terminal and it was taking the port.

Now that I have 2 Propkeys assembled here, I officially have a Propkey cluster! ;)

The T-962 seems to be a sturdy and well constructed device. The complaints I read about excessive fumes and heat on the counter were not my experience. The firmware is definitely rough. It appears to do a crude PI control on heat up, but during cooldown it really could use some help. It oscillates between running the fan to keep the actual within 10degC of target, but then it overshoots and turns on the heaters!

The oven works for the intended purpose, and the tray and interior are all made of stainless steel, quite sturdy too. The slides on the drawer are a little stiff, but not jerky. I suspect loosening the bolts and allowing it to realign may help, that or just working the slides a bit. It appears to have a pair of ball bearing slides, but I didn't look real hard.

I read that it uses an AVR to run the oven, but others said ARM. Perhaps when I get bored I might put a prop in it! :)

After assembling 1 unit by hand, I think it could be doable to hand assemble at home, but I'll need to get a solder stencil for sure, the syringe method didn't work that great.

I'm using some Amtech 63/37 no-clean solder I've had in the fridge for 10 years :) It seems to still work fine, but I may consider getting some more paste in a jar for stencil use.

I really want to build a PnP machine, and I've got some ideas I shared with the guy that started OpenPNP. I just need to get a couple of tools moved into my shed so I can do some prototyping.

Cluso99
06-05-2012, 08:07 AM
Congratulations!

For hand soldering, a fine solder and a temperature controlled iron will be fine. But the real secret here is to use a flux pen to wipe on the pcb and the underside of larger IC pins. They then solder quite well and after a little practice you will not require solder wick to take off the excess. Any bridges can be easily wiped by your iron after removing sloder on the sponge first. I dont use a stencil for hand soldering.

Interesting comments regarding the T-962 software. If its an AVR then you can reprogram with the prop. But I agree, probably easier to control with a prop ;)

pedward
06-05-2012, 08:40 AM
I've got a temp controlled iron and some .020 solder, but that's a bit heavy for the fine pitch stuff. Sure, it works, but it isn't pretty. I was using solder paste applied with a syringe and cut down 20ga needle. It worked, but was a little messy and difficult to control because the force required to get the paste to come out was high, and then the paste was a little finicky. I can get a Polymide stencil for a reasonable price, the chinese folks sell metal stencils for $35, but it's chemical etch and that company has some quality issues. The guy who does the Polymide stencils uses a laser cutter to make them, so they are fairly accurate.

Cluso99
06-05-2012, 09:04 AM
I am using .020" solder. As long as the older joint is good, then a little too muchsolder is not a problem for this market. If I was selling the boards commercially for $x00's that would be a completely different matter.

Yes I understand the polymide stencils are fine for low volumes.

Another tool we need is a prop controlled syringe paste delivery system ;)

pedward
06-06-2012, 05:38 AM
Well, I successfully produced 2 boards tonight, the solder paste application proves to be the most hassle. I used a large bore tip tonight and that was much easier, but messy. I really need a stencil for these.

The reflow oven works quite well. I still haven't had any problems with the bottom side on the second operation. The problem with too much solder seems to be that components move around too much, so I had a bit of hand rework, and solder bridges, to fix.

Placing the components is pretty simple, especially since I picked similar part values for many of the components.

Next up on the list is to order a medium run batch of boards, a stencil, and components. I should also make a test fixture to ensure all the I/O's are operating correctly and not bridged or open. I'll look for some solder pogo pins.

Also, thanks to Tubular's information, I'm going to pick up the 2.65mm tall uSD sockets, making it much less likely to break a uSD card where it plugs in.

T Chap
06-06-2012, 09:53 AM
For those few parts and just for a handful of boards, I would not use a stencil or oven. I would use a combo of rework station and pencil. Radio Shack sells a very fine silver bearing solder that is great for SMT work. I would put some flux on the pads, use the fine solder and coat the pads, then place parts with tweezers and use hot air from a rework station. If you were doing multiples on a panel and had a stainless stencil then it would be much easier.

Please post some pics when you can!

pedward
06-06-2012, 06:44 PM
T Chap, I'm trying to work out a usable small scale production solution. I want to offer the PropKey, but commercial manufacture is too expensive and requires a good chunk of capital that I don't have. Ironically, the most expensive single component in the commercial quote was the PCB. At the end of the day, I'll probably make around 75-100 PropKey's at home and re-evaluate commercial production. I'm also working towards an OpenPnP solution for home assembly.

T Chap
06-06-2012, 08:37 PM
I can relate. I created an app for a PNP that drives a Prop board via USB, the board is dedicated to 3 steppers on a CNC. The board is switchable from USB to parallel port so CNC software can be used or the PNP app. I export the XY coords out of eagle for the boards, load them in the app, save the board with a name. I have a wall with cut tape in strips of 15" pieces, much faster and easier to manage that loading full reels. The tape is manually incremented with a push button, and manually loaded for each tape. Press a but and the part gets placed, increment to the next part and place it or load the next tape. It is slow compared to a real PNP machine, but is a lifesaver since all you do it insert the tape, hit Place Part. An hourly employee runs it, so for example a part that has 125 passives takes an hour, and my cost is under 15 in labor for the board, which I cannot get close to for small volumes with anybody else. Sunstone makes the boards in 12" x 14" panels, with various boards on a panel. They are a 2 day turn, and all I have to do to order is upload the Eagle .brd file only and specify how many. Hi Tech Stencils is pricey but work great.

I use a Rockwell Bladerunner to cut the boards out, and a belt sander to clean the edges.

https://www.rockwelltools.com/us/BladeRunner_Saw-P1564.aspx

If you have a CNC, you can rig up a PNP with a vacuum and syringe, I have some of the sites for the needles if you need. With a cheap benchtop CNC you can crank out your small boards in a day, easily 75 to a 100 in a day or 2 if there were panelized.

Duane Degn
06-06-2012, 08:46 PM
I'll look for some solder pogo pins.

I'm not sure if you know this, but SparkFun sells pogo pins (http://www.sparkfun.com/products/9174).

If someone has a less expensive source, I'd like to know about it.

pedward
06-06-2012, 09:59 PM
TChap, I had a MaxNC 15 once, terrible quality on the spindle assembly. The collet runout on the 1/8" shank was > .005 and caused a load of broken tools. Of course I wasn't aware of this until years later when I fired it up before selling it, then I said to myself: "No wonder I had so many problems!".

I'd recommend Sherline, although the fancy anodizing and purpose-built design hooked me when I bought it! ;(

I'm going to build a gantry design with linear rails on an 18x18 piece of Aluminum. I've already outlined the design, I just need to prototype it. The intention is to have a bunch of space at the front for either reel feeders or cut tape, both will feed with the same method. Then room for trays, with a fixed X/Y zero set of rails to form the left and top sides of the fixturing system. I don't want to go into too much detail at the moment, but once it's ready to show, I'll post.

And it certainly will use a Propeller!

Cluso99
06-07-2012, 02:23 AM
pedward: Just be careful not to assemble too many until you know the demand. I would not like for you to put all you $$s into a project until you knw it is going to succeed. At least if you have unassembled parts you can use them on another project.

pedward
06-07-2012, 02:40 AM
Oh, for certain I'm aware of that folly. I'm going to order the min quantity of medium run boards (150 sqin) via DbPDX, which should be around 65-70. I'll make 10 or 20 to start, then it's just a matter of ordering more components.

pedward
06-08-2012, 10:24 PM
Thought I'd post a picture of 2 of the first 3 prototype release candidates I made using the reflow oven.

http://forums.parallax.com/attachment.php?attachmentid=93398&d=1339190645

Cluso99
06-09-2012, 03:55 AM
pedward: Have you sent your final pcb out for production yet? Now that I can see the assembled board in the flesh perhaps I can offer some suggestions.

pedward
06-09-2012, 06:29 AM
I haven't order a batch yet.

Cluso99
06-09-2012, 08:28 AM
Looking at your design I am wondering if it would be possible to place your more difficult smt parts (prop, ftdi, uSD connector) on the one side of your pcb, with the other jellybean parts on the other.

You can save space by using resnets for the 10K resistors (try digikey CR6S8xxxx) - they are 0603 style in a 1206 package. Use longer smt pads to make the soldering easier.
You can reduce the parts by one by using a sot23 transistor with inbuilt 10K BE resistor with either a series 470R or 1K into the base - saves the BE resistor.

I have not used a reset sw on any of my designs. Is this important??

I note you are using the 3v3 from the ftdi. With a prop and microSD you are likely on the limit of what the ftdi can supply. Have you considered putting an optional 3v3 sot23 regulator on the pcb? Your 10uF cap will be required on the input and another on the output. You can use via's .020" to make the links to minimise space.

These are just some ideas that may interest you. Try and put a gnd and a power plane under the prop if possible.

pedward
06-10-2012, 04:51 AM
Question, I'm working on the final board layout for the prototype memory daughter board for the PropKey. This is a board which is intended to mount on the bottom side of the PropKey and provide 512KB (or 256KB) of SPI SRAM (8 bits wide) and 16MB of SPI flash (8 bits wide). I was thinking of putting a VGA connector on the end of this board. Does anyone think this would be neat, or a feature that really isn't useful? Perhaps a separate board, with VGA and other peripheral connectors would be more useful.

I intended the board to be used primarily for development, but anything is possible, I don't know how others may use it.

jazzed
06-10-2012, 05:52 AM
Question, I'm working on the final board layout for the prototype memory daughter board for the PropKey. This is a board which is intended to mount on the bottom side of the PropKey and provide 512KB (or 256KB) of SPI SRAM (8 bits wide) and 16MB of SPI flash (8 bits wide). I was thinking of putting a VGA connector on the end of this board. Does anyone think this would be neat, or a feature that really isn't useful? Perhaps a separate board, with VGA and other peripheral connectors would be more useful.

I intended the board to be used primarily for development, but anything is possible, I don't know how others may use it.


Maybe Ken can use it for "PropellerPoint" Presentations ...

Rayman has already demonstrated some good graphics reading from SST26VF parts.
Winbond parts and SPI-SRAM would probably be too slow for video setup times.

pedward
06-10-2012, 06:10 AM
Not if the video is on the same pins as the I/O. But then it would be a bunch of garbage during other times. With VGA at 25Mhz, you could make it work if you did 320x240 actual pixels, but 640x480 is too fast. Those SPI parts are around 66Mhz, so that isn't the choke point. If you had 2 COGs reading data, you could get 40MB/s from the SPI.

pedward
06-27-2012, 07:57 AM
I put a medium run order of PropKEY boards on order, 80 to be exact. I don't know when they will show up, but they have been ordered. I'll post more once I've got details.

mindrobots
06-27-2012, 10:18 AM
Yay!! I need one because my coworkers at my day job are starting to wonder about the strange little boxes and boards I plug into my work computer while I sit at my desk....must be some sort of corporate terrorist!!

groggory
06-27-2012, 11:09 PM
Hey, would anyone be interested in one of these as a kit? I have all of the SMD components on hand, reels of them. I could put together kits or sell bare boards, I figure most people would want a finished board or a kit, not a bare PCB. I am also thinking of adding a micro SD socket to the board, Molex has a very compact socket that would be easier to add.

The Prop is a .8mm pitch and the FT232RL is .65mm pitch, the passives are SOT-23, 0603, 0805, and 1208. The reset button is a nice tactile momentary PTH device. The soldering does present a challenge, but not a huge challenge.

EDIT: removed shots and put new ones at top.

I'm down for a kit. This would be super handy for portable testing and prototyping

Peter Jakacki
10-05-2012, 02:45 PM
I put a medium run order of PropKEY boards on order, 80 to be exact. I don't know when they will show up, but they have been ordered. I'll post more once I've got details.
How is the "toy" coming along? Do you have any yet? I could do with one or two.