[Gmecm] Any USB developers out there?

Thu Dec 28 19:01:51 UTC 2006

Dave,

Not really, just wanted to get some components in tight spots. I could probably upsize to 0603 or maybe even 0805 and get the same 
effect.

Best regards,
Craig Moates

----- Original Message ----- 
From: "David Murray" <murr32 at shaw.ca>
To: <gmecm at diy-efi.org>
Sent: Wednesday, December 27, 2006 12:00 PM
Subject: Re: [Gmecm] Any USB developers out there?

> Craig,
>
> I have used an Alpha-Metals solder with a water soluble flux core, available through Digi-Key (www.digikey.com) I think.  Any 
> reason you jumped directly to 0402 components from 1206 (or 0805)?  I have found I can squeeze most designs, with the exception of 
> high-complexity small space boards like cell phones, using 0603 parts; though I haven't looked at your scematic or layout yet to 
> see how tight a fit everything is.
>
> Cheers
> Dave
>
> ----- Original Message -----
> From: Craig Moates <craig.moates at cox.net>
> Date: Wednesday, December 27, 2006 10:23 am
> Subject: Re: [Gmecm] Any USB developers out there?
>
>> Hi Steve,
>>
>> Here's a link to DB9 cables:
>> http://www.obd2cables.com/products/
>> Cheapest I could find around, sub-$10 in bulk, sub-$20 even
>> individually.
>> My wife and I do the 0402 all the time by hand (she doesn't like
>> them!), it's not bad at all but it definitely takes some getting
>> used to. Of course if you drop one, might as well forget about it
>> and grab another. Just use magnifying head gear, 0.015" organic
>> core solder, tweezers, and a fine tip. Regarding paste, I've used
>> it with hot air and not had the best of luck. Little balls tend to
>> float around and up under stuff (was trying to do a TQFP144
>> package that way). Had a lot better luck just laying it down
>> normally
>> and coming back with the wick as needed. Not sure about the aging,
>> but I gave up on it. I suppose it's fine for volume production
>> using stencils and pick-n-place.
>>
>> By the way, anyone know of a water-soluble fluxed wick that works
>> well? The stuff I use works OK, but leaves solvent-needy residues
>> instead of full water clean. I'd like to have some better wicking
>> material.
>> Yes, you can supply a good 100mA or so from just about any USB
>> bus. Fairly decent power supply, not too noisy.
>>
>> I did cross-check the board dimensions compared to the recommended
>> PCB size for the Pactec enclosure, and I have some of them in
>> hand. Appears to be correct, but they'll need to be trimmed pretty
>> closely to actually fit. Also, the hole for the USB side is
>> actually for an RJ11, so it'll be slightly too big. I've seen
>> where some folks have used a rubber O-ring around the USB
>> connector to
>> center that end of the assembly in the enclosure, that works well.
>> But the USB side of the board might need to be set back slightly
>> to allow for that placement.
>>
>> I'll see about setting something initial up in C then. Been trying
>> to force myself more in that direction on new projects. Gives a
>> lot more flexibility and portability.
>>
>> For PCBs, if you've got anything you want run, just let me know. I
>> can saddleback what you've got into one of my submissions. I try
>> to put some 'known good' stuff in with the proto projects so that
>> it isn't a waste if it doesn't work out. I put in 60 square inches
>> of various prototypes to www.4pcb.com at least every 2 weeks under
>> their www.33each.com offer. For the arrays, you can squeeze a lot
>> of stuff into 60 square inches (their limit) and get 3 boards
>> (their minimum) for $99 plus $50 (their upcharge for
>> step/repeat/array
>> characteristics). Lead time is 5-7 business days. Not a bad deal.
>> There's some other deals out there, but I've had good luck with
>> these guys. As long as you keep your spacing wider than 8 mils or
>> so, and use traces of 8 mils or better and vias of 12 mils or
>> better you should be OK. I usually go with 10 mil spacing, 10 mil
>> trace width, and 16 mil via mininums.
>>
>> Best regards,
>> Craig Moates
>>
>>
>> ----- Original Message ----- 
>> From: "Steve Ravet" <Steve.Ravet at arm.com>
>> To: <gmecm at diy-efi.org>
>> Sent: Wednesday, December 27, 2006 1:14 AM
>> Subject: RE: [Gmecm] Any USB developers out there?
>>
>>
>> Hey Craig, thanks for sharing.  I have a few questions:
>>
>> Is the 9 pin to OBD2 cable something that is standard or one of your
>> cables?  I used a DB-15 on mine, but was planning on moving to a
>> DB-25
>> to allow more of the PIC pins to be pinned out (ie misc analog and
>> digital I/O).  But if the DB9 is standard I may switch to it.
>>
>> I guess you use solder paste to do 0402?  In your experience (or
>> anyoneelse), does solder paste really go bad within a month?
>>
>> After looking at yours I realized there's no reason to have the 5V
>> regulator in there, might as well always have the VCC stuff
>> powered from
>> USB.  Eliminates parts and makes the BOM that much cheaper.  I'm also
>> going to use your board layout to fit the Pactec enclosure.
>>
>> I'm writing my firmware in C, since microchip assembly makes my head
>> hurt.  As far as the host interface, I had planned on implementing the
>> SAE J2534-1 API.  (Yes, this is an SAE spec that specifies a windows
>> API).  This is a standard API for vehicle reprogramming but the
>> API is
>> generic enough to work for normal scan tool operations also.  The spec
>> requires support for all vehicle protocols but USBVPW will only do
>> VPW.That SAE spec is now on the USBVPW wiki page, take a look.
>>
>> What do you think your BOM cost is, including the PCB?
>>
>> Speaking of PCBs, I have a number of small (couple square inches or
>> less) projects I've been wanting to do but it seems like most PCB
>> housesget offended if you do arrayed PCBs.  Is there a PCB place
>> that will do
>> a 4x6 PCB with many individual circuits on it and not want to give me
>> all kinds of per project charges?  Otherwise the cost for these
>> one-offs
>> is prohibitive.
>>
>> --steve
>>
>> > -----Original Message-----
>> > From: gmecm-bounces at diy-efi.org
>> > [gmecm-bounces at diy-efi.org] On Behalf Of Craig Moates
>> > Sent: Monday, December 25, 2006 3:01 PM
>> > To: gmecm at diy-efi.org
>> > Subject: Re: [Gmecm] Any USB developers out there?
>> >
>> > Folks,
>> >
>> > I updated the layout, and it's probably ready for a proto
>> > run. Check it out if you like:
>> > www.moates.net/projects/
>> > Got tired of trying to squeeze those beefy 1206s in there so
>> > went to mostly 0402. They're doable with magnifier and tweezers.
>> >
>> > All the components are specified, laid out pretty well, and
>> > labeled on the schematic and silkscreen.
>> >
>> > I'll start working on the firmware shortly. Prefer C++ or
>> > ASM? Guess I'll make it compatible with some of the 'other'
>> > stuff out there.
>> >
>> > Best regards,
>> > Craig Moates
>> >
>> >
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