[Coco] CoCo Altera DE1 interface

Sat Jan 17 10:15:06 EST 2015

Kip,

Fortunately, I just meant that where I once was able to focus and get
precision by just putting my eye 1/2" away from the surface I now need to
be 8" away and/or use a loupe to do the same job.  :-)  It makes SMD
harder, but it's actually easier than you might think if you choose
reasonable devices.  Sorry for the misunderstanding.

The main two advantages of the chip I chose is high density and the ability
to interface with 3.3v logic.  The LS244/245 set are fine, but you would
need 5-6 chips, and you would still only be able to work at 5v.  It all
depends on what problem you want to solve.  I wanted to hook it up safely
to newer microcontrollers and FPGAs, which necessitated at least having
3.3v support.

Like everything else, SMT soldering requires practice.  Also, a nice pair
of tweezers.

Matt

On Fri, Jan 16, 2015 at 11:32 PM, Kip Koon <computerdoc at sc.rr.com> wrote:

> Hi Matthew,
> I sorry to hear you eyesight is failing.  My prayers are with you.
> I have been thinking of using the buffers chips you used for your CoCo
> Interface PCB you made to connect to a DE1 PCB in my Coco Hardware
> Interface Kit.  I have also been thinking of using some 74LS244N and
> 74LS245N Buffer chips as well in my next version.  I really admire how you
> as well as others are able to wield surface mount chips!  I suppose I will
> have to get my SMT feet wet in the near future.  :P  Do you have any advice
> from one designer to another?
>
> Kip Koon
> computerdoc at sc.rr.com
> http://www.cocopedia.com/wiki/index.php/Kip_Koon
>
>
>
> -----Original Message-----
> From: Coco [mailto:coco-bounces at maltedmedia.com] On Behalf Of Matthew
> Stock
> Sent: Friday, January 16, 2015 11:30 AM
> To: CoCoList for Color Computer Enthusiasts
> Subject: Re: [Coco] CoCo Altera DE1 interface
>
> No, I don't see them anymore, so I figured I'd put the design out for all
> to use.  The caps are just 0805 (I think) .1uF decoupling caps.  I used
> more than is really needed, but they are cheap and don't take up a lot of
> room.  But I think Kandur's question might have been related to the other
> board, which uses Cn as a connector - looks like a 40 pin .1" header
> similar to mine.  Main difference between the two designs is that I have
> the buffering on the board and lay the 40 pin header out differently.  I
> believe Kip was also building his own breakout board using through hole
> materials.
>
> Even with my eyesight slowly failing, I have a fairly reliable way to
> solder these chips.  Use a flux pen on all of the pads, and use tape to
> position the chip exactly where you want it - use a magnifier to make sure
> everything lines up well.  Then, put a fair amount of solder on all the
> pins - don't worry about bridging.  Finally, use solder wick to pull up all
> of the solder.  There will be just enough solder under the pads remaining
> to keep a good connection.
>
> The other method is to use solder paste on each of the pads, place the
> chip reasonably accurately, and then indirectly heat the board/chip to melt
> - I use one of the SMD heat guns for this, but the right way to do it is a
> real temp controlled oven, etc.
>
> I've had more luck with the first method, but obviously it only works for
> low volume jobs.  Good luck!
>
> Matt
>
>
>
> On Fri, Jan 16, 2015 at 11:17 AM, Gustavo Ranaur Schoenaker <
> ranaur at ranaur.net> wrote:
>
> > Mathew,
> >
> > Do you still sell them? If not ... no problem, it will be fun to
> > solder SMD. I'll do it on OSHPark, but, reinforcing the question from
> > Kandur, what are the capacitors (Cn) on the board?
> >
> > Thanks!
> >
> > On Fri, Jan 16, 2015 at 1:33 AM, Matthew Stock <stock at bexkat.com> wrote:
> >
> > > Hi Gustavo,
> > >
> > > Yes, I'm still lurking.  I have used the board pretty extensively
> > > for my FPGA projects and found it useful.  A few others have used it
> > > as well so far as I know.  Since it does the level conversion for
> > > 3.3v logic and follows the same pinout as the Altera boards, you can
> > > use a straight
> > ribbon
> > > cable to connect the two.
> > >
> > > Some of my Coco FPGA work is up on Github
> > > (http://github.com/mattstock/, including a few iterations of a
> > > multi-ROM system that was programmable
> > via
> > > SPI from an Arduino, the start of a microSD-based disk drive
> > > replacement (that was implemented much more elegantly by Darren well
> > > before I
> > finished
> > > mine), and some other odds and ends.  Feel free to take a look, and
> > > let
> > me
> > > know if I can be of any assistance.
> > >
> > > I haven't been working on Coco projects recently though - I've
> > > actually been working on a new CPU and machine design implemented in
> > > an FPGA as a fun little experiment.  I've needed to delve into
> > > building a cross assembler and cross compiler, and doing all three
> > > in parallel has been
> > very
> > > enlightening.  Not Coco, but if you're interested feel free to take
> > > a
> > look
> > > at these and other projects at Github.
> > >
> > > I may bring it back around to the Coco at some point, who knows.
> > > :-)
> > >
> > > Matt
> > >
> > >
> > >
> > >
> > > On Thu, Jan 15, 2015 at 9:31 PM, Gustavo Ranaur Schoenaker <
> > > ranaur at ranaur.net> wrote:
> > >
> > > > Hi
> > > >
> > > > While browsing in OSHPark I found two projects: CoCo Buffer (
> > > > https://oshpark.com/shared_projects/1qtqcHjF) and Slot Extender (
> > > > https://oshpark.com/shared_projects/ixlqJKlZ).
> > > >
> > > > Looking on the old posts of the list I think the first one was
> > > > made by Mathew. (are you there, Matt? :)
> > > >
> > > > Does anyone used it? Is there any project example to connect the
> > > > Altera FPGA with the CoCo? I would love to try it,
> > > >
> > > > On Fri, Oct 31, 2014 at 12:41 PM, Matthew Stock <stock at bexkat.com>
> > > wrote:
> > > >
> > > > > Hi Tim,
> > > > >
> > > > > I don't have any on hand, but if you can solder the fine pitch
> > > > > chips
> > > you
> > > > > can order them from Digikey and OSHPark directly.  I can order
> > > > > and
> > > > assemble
> > > > > them too if you prefer, but it will be more expensive that way.
> > > > > Send
> > > me
> > > > a
> > > > > note directly if you want to discuss either option:
> > > > > stock at bexkat.com
> > .
> > > > >
> > > > > This little buffer interface is useful for non-Altera boards,
> > > > > but the pinout allows you to take a normal 40-pin ribbon cable
> > > > > and plug it
> > from
> > > > > Coco to DE1 without any fuss.  It's been really handy for my
> > > > > projects
> > > and
> > > > > tinkering.
> > > > >   -Matt
> > > > >
> > > > >
> > > > > On Fri, Oct 31, 2014 at 10:29 AM, tim at franklinlabs.com <
> > > > > tim at franklinlabs.com
> > > > > > wrote:
> > > > >
> > > > > > Yeah, at this point it's the LE count. I don't need 1/3 of the
> I/O.
> > > I'm
> > > > > > really
> > > > > > not sure yet on the LE count either. Just thinking ahead. I
> > > > > > haven't prototyped the design yet but I will using a DE-1. I
> > > > > > am planning on using the
> > > > > Cyclone
> > > > > > series on the final design.
> > > > > >
> > > > > > I need to get in touch with Matt Stock (CoCo e-mail participant).
> > He
> > > > was
> > > > > > selling
> > > > > > a DE-1 interface board at one point. I found his board on OSH
> Park.
> > > If
> > > > > he's
> > > > > > still around and reading this... Can I still get one or two of
> > those
> > > > > > boards??????
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > > > On October 31, 2014 at 9:09 AM Mark McDougall <
> > > msmcdoug at iinet.net.au
> > > > >
> > > > > > wrote:
> > > > > > >
> > > > > > >
> > > > > > > On 31/10/2014 3:42 AM, tim at franklinlabs.com wrote:
> > > > > > >
> > > > > > > > I actually haven't chosen the actual FPGA yet because I'm
> > > > > > > > not
> > > sure
> > > > > how
> > > > > > much
> > > > > > > > LE
> > > > > > > > space I need. I was considering a small Cyclone III or
> > > equivalent.
> > > > > The
> > > > > > one I
> > > > > > > > was
> > > > > > > > looking at I thought was 264 pins but it actually was 408.
> > > > > > >
> > > > > > > Wow, do you *need* that much I/O for your project? Or is it
> > > > > > > a
> > case
> > > of
> > > > > the
> > > > > > > smallest package for that many LE's?
> > > > > > >
> > > > > > > I've done TQFP soldering by hand, but I think that was
> > > > > > > 144-pin,
> > and
> > > > > > quite a
> > > > > > > few years ago before my sight started failing me. It's not
> > > > > > > as
> > hard
> > > as
> > > > > > you'd
> > > > > > > think as the solder tends to stick to the pin/pad.
> > > > > > >
> > > > > > > I've got a homebrew project now with a PQFP 240-pin Cyclone
> > > > > > > III
> > and
> > > > I'm
> > > > > > not
> > > > > > > going to stuff around with, I'll bite the bullet and get it
> > > > assembled -
> > > > > > > probably a run of 8.
> > > > > > >
> > > > > > > Regards,
> > > > > > >
> > > > > > > --
> > > > > > > | Mark McDougall | "Electrical Engineers do it
> > > > > > > | <http://members.iinet.net.au/~msmcdoug> | with less
> > resistance!"
> > > > > > >
> > > > > > > --
> > > > > > > Coco mailing list
> > > > > > > Coco at maltedmedia.com
> > > > > > > https://pairlist5.pair.net/mailman/listinfo/coco
> > > > > > mattstock <https://oshpark.com/profiles/mattstock> .
> > > > > >
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> > > > > >
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> > > > >
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> > > >
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> >
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> >
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