A propeller USB stick

Tubular · 2012-03-27 14:55

The new compact FT230X lets me do something I've wanted to do for a while - a plug in "memory stick" prop circuit, for development. Just the basics - FT232R (equiv), xtal, micro sd, regulator, eeprom.

This board is 1.44" (37mm) long, and 1/2" wide

There are 8 GPIO (P16~23) are connected by a 10 pin IDC ribbon to the back of the board, and superglued or heathrink for strain relief.

I'm not using the 'extra components' associated with the FT230XS. If it doesn't work there are links for standard TTL (ie prop plug)

Edit: Assembled photo added

jazzed · 2012-03-27 15:29

Tubular wrote: »

The new compact FT230X lets me do something I've wanted to do for a while - a plug in "memory stick" prop circuit, for development. Just the basics - FT232R (equiv), xtal, micro sd, regulator, eeprom.

Nice board. My USB stick suffered from my fat soldering fingers with the QFN.
I've been thinking about that smaller chip too

I have 9 or 10 clear USB enclosures if you want them.

Tubular · 2012-03-28 18:06

Thanks Jazzed

I bought a couple of similar enclosures from Element14. They may even be the same - one half has an oval recess and the other half a rectangular recess. Does that sound right?
Here's the link to what I bought... http://au.element14.com/multicomp/mcg1901/box-usb-plug-in-clear/dp/1603603

If it is the same, the board fits in easily as you can see from the photo below.

There's another company New Age Enclosures who have small usb enclosures, available through Mouser. It would be great to make an even shorter board, my mounting most of the components on the underside below the prop.

Cluso99 · 2012-03-28 21:54

Nice job tubular

Peter Jakacki · 2012-03-28 22:34

Looks good. How come you went with the 8-pin LDO? I normally just use the SOT-23 packages. I'm guessing that the one you are using is stable with small output caps? The reset transistor could easily be a digital type so you wouldn't need the base resistor (minor). However I really hate HC49 rocks, they are big and bulky and the leads are really too far apart for my liking. Have you tried the NX5032GA series available from DigiKey, they are very cheap and small and smd at only 5mm x 3.2mm.

The microSD header looks neat, I didn't realize they were available.

Can I get an assembled pcb off you when you're done? Just for the fun of it.

Tubular · 2012-03-28 22:56

Sure you can get one. I'll be up your way in about 6 weeks, perhaps can deliver in person. You can give me a QFN soldering lesson.

The LDO - I like the way it lets the P0-P3 pass under en route to the SD card, and the symmetry with the msop eeprom. Its stable with 1uF, and its easy enough to get 4.7~10uF ceramic in 0603 for extra margin. But yes there are more compact alternatives. Rearranging it may be possible to squeeze 5mm of length by changing to a small reg, and putting the xtal where the tc1107 is now...

The Xtal certainly is the elephant of the design now. Previously it was the FT232RL.

Thanks for the link, I'll check those xtals out. The xtal is about the same size as the uSD socket ("header").

jazzed · 2012-03-28 23:05

Tubular wrote: »

Thanks Jazzed

I bought a couple of similar enclosures from Element14. They may even be the same - one half has an oval recess and the other half a rectangular recess. Does that sound right?

That's the one.

That leaves plenty of room for options like byte-wide QuadSPI chips for big XMMC programs.
I was planning to distribute PropellerGCC packages on the SD Card later.

For +5V to +3.3V regulation I've been using TI 73633 in 5SOT-23, 0.4A Iout, 75mv Vdo, 0.3ma Iq, 1% Accuracy, Caps optional.

jmg · 2012-03-28 23:09

The best idea for a 'user board' is a range of XTAL footprints : Give users the option.

Whilst the HC49/u may be large, it is widely available.

Note too, that the relatively low default clock of the Prop, excludes some packages.

jmg · 2012-03-28 23:11

Tubular wrote: »

I'm not using the 'extra components' associated with the FT230XS. If it doesn't work there are links for standard TTL (ie prop plug)

I'd be more relaxed about leaving off the Caps, than the series R's. They will help the ESD tolerance, and on something that will be on a bench, with cables connected, that detail matters.
I'm sure there is room to fit 2 SMD resistors, even on the back of the board ?

Peter Jakacki · 2012-03-28 23:20

Have you tried using cap arrays which have 4 caps in the one tiny package? I noticed that you kept everything on the one side of the PCB but I have had no problems assembling one side at a time. When you bake one side in the oven you can then assemble the other side of the pcb and put it back in the oven and the previous parts on the bottom just stay on through the process. Provided you don't have any big and bulky parts this method always works.

Tubular · 2012-03-28 23:36

jazzed wrote: »

I was planning to distribute PropellerGCC packages on the SD Card later.

For +5V to +3.3V regulation I've been using TI 73633 in 5SOT-23, 0.4A Iout, 75mv Vdo, 0.3ma Iq, 1% Accuracy, Caps optional.

That's a great idea (the packages dist on SD card...)

And nice regulator too. I like the "caps optional" - haven't seen that before.

Tubular · 2012-03-28 23:41

jmg wrote: »

I'd be more relaxed about leaving off the Caps, than the series R's. They will help the ESD tolerance, and on something that will be on a bench, with cables connected, that detail matters.
I'm sure there is room to fit 2 SMD resistors, even on the back of the board ?

I did think about it, but they are only 27 ohms. I'm actually quite curious about their exact purpose - is it something in the USB spec? Or are they trying to match cable impedance that varies from one manufacturer to another, or a slight EMC filter on output (27 ohms + 47pF)?

But you're right I could add some pads on the back. There are a few "optional component" pads on the back already - a TAJ-B tantalum in case its needed for SD card reliability, and some leds and corresponding resistors for power and P16~P23.

Peter Jakacki · 2012-03-28 23:43

The TI part is expensive and definitely overkill. I use several different regulators but the TC1185 is more than adequate and cheap. Sure it's only 150ma but I use it in Prop systems with SD cards no problems whatsoever.

BTW, Resistor arrays save a lot of room and are the same price as a single resistor. Use this for the 27R in the USB line. You could also use 56R resnets and parallel etc.

Tubular · 2012-03-28 23:47

Peter Jakacki wrote: »

Have you tried using cap arrays which have 4 caps in the one tiny package? I noticed that you kept everything on the one side of the PCB but I have had no problems assembling one side at a time. When you bake one side in the oven you can then assemble the other side of the pcb and put it back in the oven and the previous parts on the bottom just stay on through the process. Provided you don't have any big and bulky parts this method always works.

I didn't really enjoy soldering Cluso's Ramblade resnets, but I guess I could revisit 4-packs...

I might have a crack at revising the layout based on two sides heavily populated, and your component suggestions (thanks). This is the target case it would be great to squeeze into...

Peter Jakacki · 2012-03-28 23:56

You're not supposed to "solder" these components. Spend $29.95 and get yourself a toaster oven to dedicate for this and grab a syringe of fresh solder paste. I get my paste and stuff from OKAY Technology (Chemtools). Let me know if you need some details. I bought a tube of paste from Jaycar one time in desperation, it was supposed to be fresh but it was totally unusable.

MacTuxLin · 2012-03-29 01:40

Tubular,

This looks great!

Cluso99 · 2012-03-29 02:23

I am now used to hand soldering the smt resistor pack w/o any problems at all. Still to try the toaster.

Here is the SOT23 regulator 6Vin 3V3 out 250mA (use big pads) MCP1700T3302ETTCT-ND

Here are two 0805 10uF 6V3 Ceramic caps from DigiKey...

445-1363-1-ND490-1718-1-ND

A t/hole xtal will actually take less pcb space but of course both sides. If you use 0.040" holes you can fit the xtal socket pins.
ED5037-ND

Not sure if you have the transistor reset cct. I am now using a SOT-23 transistor with series base and base-emitter resistors (Thanks Peter). IIRC they are 470R series and 4K7 B-E. It saves the 10K B-E resistor. You could actually omit the series resistors (or use resnets) for P31 & P30 since the FT chip is 3V3 I/O. (I have not checked your circuit to see if they are present.

And as Peter said, put some components underneath - at least the resistors and caps.

I have some of all of the above, and 56R (IIRC) resnets if you need a few.

Peter Jakacki · 2012-03-29 06:55

The NX5032GA crystals are very small and I buy them for around 48 cents each. Here's a screen shot of a SMD HC49 just above the NX5032GA crystal so you can use it for size comparison. Like Cluso I have used through-hole HC49s in the past because they take up less room than their SMD counterparts and do not have those huge pads that SMD versions do. I have also used TH cylindrical crystals as well since the leads are close together and the casing is small, but as you can see the 5x3mm crystal is just the ticket and at the right price.

jazzed · 2012-03-29 07:04

Peter Jakacki wrote: »

The NX5032GA crystals are very small and I buy them for around 48 cents each.

Nice part. You use the 150ppm stability spec? Any drawbacks such as video artifacts?

Peter Jakacki · 2012-03-29 07:08

jazzed wrote: »

Nice part. You use the 150ppm stability spec? Any drawbacks such as video artifacts?

Can't really say about video as I haven't really tried it (yet) although I have boards I could try it on. The part is specified as being +/-30ppm though.

jazzed · 2012-03-29 07:46

Peter Jakacki wrote: »

Can't really say about video as I haven't really tried it (yet) although I have boards I could try it on. The part is specified as being +/-30ppm though.

I look forward to hearing your results. It's a nice package.
At least a 30ppm precision/stability part is available at a price.
Is there a second source?

Tubular · 2012-03-29 16:54

Peter Jakacki wrote: »

You're not supposed to "solder" these components. Spend $29.95 and get yourself a toaster oven to dedicate for this and grab a syringe of fresh solder paste. I get my paste and stuff from OKAY Technology (Chemtools). Let me know if you need some details. I bought a tube of paste from Jaycar one time in desperation, it was supposed to be fresh but it was totally unusable.

I guess my parts choice reflect the limit of my soldering confidence, and I traditionally have drawn the line at QFN/DFN. During our summer holidays I set up a toasting area at work, complete with tiny peltier fridge to keep the tub of solder paste (as well as other chemicals) at 4 degrees or so. Got some stencils from ohararp.com (great), and other bits and pieces (solder tub etc) from Mektronics. I've run 2 or 3 tests with satisfactory results, and only had one failure which happened to be a QFN prop.

Need a more "compliant" oven - looking at what Elektor come up with, as well as some other units from France etc.

@MacTuxLin, thanks!

Peter Jakacki · 2012-03-29 20:36

I've got one of those camping coolers, the peltier effect ones too that I keep all my perishables in including the paste and even the glues etc. They draw around about 100W continuously but it's worth it to have one. I picked mine up at Aldi for around $69 or so. I have another oven that I am converting to handle this temperature control better but really the unmodified oven always seems to work well enough.

As for pcbs and stencils I've been using Storm Circuit lately and I've been really happy not only with their work but also their professionalism I guess you would call it as they check on your work and zip off a question or two if needed unlike some places that blindly follow your mistranslated instructions without any "are you sure"s. They are based in Hong Kong but they communicate like locals and are very helpful.

Second source distributor for NDK crystals is also AVNET as far as I aware. If you mean manufacturer then I'm not sure but I do dual foot-prints to allow for cylindrical ones in case there is a supply problem or else maybe allow for more choice in frequencies.

Tubular · 2012-06-08 13:53

Here's the final result. Happy with this one, though I haven't powered it up just yet.

This board was the last one added to the Smorgasboard, when there was a small 1.44"x0.51" space left over

One application might be as a automated propeller based slideshow presenter - based on the great work in the recent thread. Some monitors have a usb port which could power this. The VGA connector at the other end would plug into the VGA port of the monitor or projector.

Will get one up to you shortly, Peter.

pedward · 2012-06-08 14:22

Tubular, similar concept, but different execution:

Tubular · 2012-06-08 14:32

Yes indeed, what luxury, having enough width for GPIO pin breakout

pedward · 2012-06-08 14:45

600-mil 32 pin DIP

Tubular · 2012-06-08 16:13

One option for getting the I/O out without going wider might be to horizontally offset multiple ribbon terminations on the back. They would stack up vertically, and once out of the heatshrink that holds them all together they could go to different locations, such as different Digilent Pmod modules.

A propeller USB stick

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