[N8VEM: 17286] 6x0x prototype board status

Discussion:

Andrew Lynch

2014-02-02 14:37:30 UTC

Hi! Thanks everybody for the great work on the 6x0x prototype board
project.

Please update the notes with your findings from build and test. Especially
when correcting problems with the board.

http://n8vem-sbc.pbworks.com/w/browse/#view=ViewFolder&param=Build%20and%20T
est%20-%20rev008

I am aware of some problems on the PCB so far:

1. The MMU needs a wiring fix to solve a race condition

2. The /RESET line needs to be pulled high

3. The PS/2 keyboard and mouse ports are miswired

4. The jumper (SIL-2) drill holes are too small

5. Clearance issues with the serial port headers

6. There is a problem with the ATX mounting holes which may be related
to a DIN 49612 footprint misalignment

Are there any other schematic and/or PCB problems not in the list above? I
would like to fix all of these items before a production board.

I uploaded the EDA file set to the wiki if this would be of help to the
build and test debugging.

As always, many photos of your build and test greatly appreciated and it
makes fixing PCB issues a whole lot easier.

Thanks and have a nice day!

Andrew Lynch

--
You received this message because you are subscribed to the Google Groups "N8VEM" group.
To unsubscribe from this group and stop receiving emails from it, send an email to n8vem+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/***@public.gmane.org
To post to this group, send email to n8vem-/JYPxA39Uh5TLH3MbocFF+G/***@public.gmane.org
Visit this group at http://groups.google.com/group/n8vem.
For more options, visit https://groups.google.com/groups/opt_out.

Borut

2014-02-02 21:33:41 UTC

Permalink

Andrew,

JP12
Installing this jumper allows /NMI to lock up. /NMI is driven from the

bus on p5. of the schematic, lower left corner. However, it is aliased to
B_/NMI on p10. at the top.
The same applies to IRQ.

There is also a problem with cache ram address lines if you want to use 8k
ram instead of 32k.
My initial plan was to use 61c64, since we are grounding A10-A14. That is
not possible, because
Cypress numbers their address lines different than JEDEC standard 28 pin
pinout - they go the other way
and what is a0 becomes a14. And that means that we are grounding a0-a4 in
other rams.
No big difference if you use a 32Kb part, but not good for 8Kb part.
I would therefore suggest that we change the layout to pull up pin 26 (CE
in JEDEC for 8Kb parts)
and pin 1 (NC) and instead connect this two address lines to pins 6 and 7.
Than both 8 an 32Kb parts could be used.
GND and VCC are equivalent on the unused lines, except VCC is what is
needed on pin 26, the positive CE.

We can pull up: 26, 1, 10, 9, 8.
Or, pull up: 26, 1; and gnd: 10, 9, 8.

I would also appreciate if we could put a pull up 4.7k resistor to PD1
(VIA1) and a header to the ground.
Than it would be possible to select console on serial port or Prop VGA/PS2
with a jumper.
Anyone who doesn't want to use this functionality only has to leave out the
resistor and jumper.

Best regards,

Bo/

Hi! Thanks everybody for the great work on the 6x0x prototype board
project.
Please update the notes with your findings from build and test.
Especially when correcting problems with the board.
http://n8vem-sbc.pbworks.com/w/browse/#view=ViewFolder&param=Build%20and%20Test%20-%20rev008
1. The MMU needs a wiring fix to solve a race condition
2. The /RESET line needs to be pulled high
3. The PS/2 keyboard and mouse ports are miswired
4. The jumper (SIL-2) drill holes are too small
5. Clearance issues with the serial port headers
6. There is a problem with the ATX mounting holes which may be
related to a DIN 49612 footprint misalignment
Are there any other schematic and/or PCB problems not in the list above?
I would like to fix all of these items before a production board.
I uploaded the EDA file set to the wiki if this would be of help to the
build and test debugging.
As always, many photos of your build and test greatly appreciated and it
makes fixing PCB issues a whole lot easier.
Thanks and have a nice day!
Andrew Lynch

John Coffman

2014-02-03 15:32:52 UTC

Permalink

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta content="text/html; charset=ISO-8859-1"
http-equiv="Content-Type">
</head>
<body bgcolor="#ffffff" text="#000000">
My edits are in italics: 
 
On 02/02/2014 06:37 AM, Andrew Lynch wrote:
<blockquote cite="mid:00e101cf2024$4e007cc0$ea017640$@YAHOO.COM"
type="cite">
<meta http-equiv="Content-Type" content="text/html;
charset=ISO-8859-1">
<meta name="Generator" content="Microsoft Word 14 (filtered
medium)">
<style></style>
<div class="WordSection1">
Hi!  Thanks everybody for the great work on
the 6x0x prototype board project.<o:p></o:p>
<o:p> </o:p>
Please update the notes with your findings
from build and test.  Especially when correcting problems with
the board.  <o:p></o:p>
<o:p> </o:p>
<a class="moz-txt-link-freetext" href="http://n8vem-sbc.pbworks.com/w/browse/#view=ViewFolder&param=Build%20and%20Test%20-%20rev008">http://n8vem-sbc.pbworks.com/w/browse/#view=ViewFolder&param=Build%20and%20Test%20-%20rev008</a><o:p></o:p>
<o:p> </o:p>
I am aware of some problems on the PCB so
far:<o:p></o:p>
<o:p> </o:p>
1.       The MMU
needs a wiring fix to solve a race condition<o:p></o:p>
2.       The
/RESET line needs to be pulled high<o:p></o:p>
3.       The PS/2
keyboard and mouse ports are miswired<o:p></o:p>
4.       The
jumper (SIL-2) drill holes are too small<o:p></o:p>
5.       Clearance
issues with the serial port headers<o:p></o:p>
6.       There is
a problem with the ATX mounting holes (unrelated to DIN
footprint, which affects backplanes only) 

</div>
</blockquote>
 
    7.  There is a clearance issue when trying to insert this board
into a VME chassis.  The margins at the sides of the board are not
enough, especially at the 16Mhz oscillator on the right.  Remember,
oscillator cans overhang the socket in which they are used.  Instead
of 100mil clearance, the oscillator requires 150mil clearance. 
 
<blockquote cite="mid:00e101cf2024$4e007cc0$ea017640$@YAHOO.COM"
type="cite">
<div class="WordSection1">
Are there any other schematic and/or PCB
problems not in the list above?  I would like to fix all of
these items before a production board.<o:p></o:p>
<o:p> </o:p>
I uploaded the EDA file set to the wiki if
this would be of help to the build and test debugging.<o:p></o:p>
<o:p> </o:p>
As always, many photos of your build and
test greatly appreciated and it makes fixing PCB issues a
whole lot easier.<o:p></o:p>
<o:p> </o:p>
Thanks and have a nice day! 
 
Andrew Lynch<o:p></o:p>
</div>
-- 
You received this message because you are subscribed to the Google
Groups "N8VEM" group. 
To unsubscribe from this group and stop receiving emails from it,
send an email to <a class="moz-txt-link-abbreviated" href="mailto:n8vem+unsubscribe-/***@public.gmane.org">n8vem+unsubscribe-/***@public.gmane.org</a>. 
To post to this group, send email to <a class="moz-txt-link-abbreviated" href="mailto:n8vem-/***@public.gmane.org">n8vem-/***@public.gmane.org</a>. 
Visit this group at <a moz-do-not-send="true"
href="http://groups.google.com/group/n8vem">http://groups.google.com/group/n8vem</a>. 
For more options, visit <a moz-do-not-send="true"
href="https://groups.google.com/groups/opt_out">https://groups.google.com/groups/opt_out</a>. 
</blockquote>
</body>
</html>



-- 
You received this message because you are subscribed to the Google Groups "N8VEM" group. 
To unsubscribe from this group and stop receiving emails from it, send an email to n8vem+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/***@public.gmane.org 
To post to this group, send email to n8vem-/JYPxA39Uh5TLH3MbocFF+G/***@public.gmane.org 
Visit this group at <a href="http://groups.google.com/group/n8vem">http://groups.google.com/group/n8vem</a>. 
For more options, visit <a href="https://groups.google.com/groups/opt_out">https://groups.google.com/groups/opt_out</a>.