[Coco] CoCo Altera DE1 interface

Fri Jan 16 23:32:21 EST 2015

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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