[Coco] Kip's Single Board Computer

[Kip Koon]

Hi John,
Thank you for your suggestions.  I will definitely check them out.

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 John W. Linville
> Sent: Tuesday, September 15, 2015 11:33 AM
> To: CoCoList for Color Computer Enthusiasts
> Subject: Re: [Coco] Kip's Single Board Computer
> 
> On Mon, Sep 14, 2015 at 09:31:37PM -0400, Kip Koon wrote:
> 
> > I apologize for not responding sooner as I have not been doing well.
> > Once I saw and read all the emails and requests to help, thanks guys,
> > here are PDFs for the Kipper SBC v1 that Retro Innovations and I have been working on.
> 
> I found your earlier post from back in the Spring and took a look at those schematics this week...
> 
> > I guess looking at the same schematic for long periods of time is not
> > good for finding errors since I could not find any until recently.
> > Here are the few errors I have noticed.
> >
> > Looking at sheet 1 of the schematic, I noticed there is no capacitor
> > across the reset pushbutton hence no RC circuit to pull the reset pin
> > low.  In the next version, I will be using an MC340649 Voltage level
> > Sensor in a TO-92 package built to properly reset microprocessors and microcontrollers.
> 
> I'm fairly certain that this is your "no clock" problem.  Page 6 of the datasheet says "During initial power on, The RESET^ line should be
> held low until the clock oscillator is fully operational."
> The missing RC circuit performs that task.
> 
> I have a Simon6809 board here that has the proper RC circuit on the RESET^ line.  As an experiment, I pulled out a pin of the capacitor
> in that circuit, essentially replicating the "no RC on RESET^" circuit as in your Kipper SBC v1 schematic.  When I did that, the board
> would not start-up when powered.  Replacing that capacitor pin connection made the board run again.
> 
> Anyway, I suspect that the "RC on RESET^" bit is all you need to get the clock running.  I don't think you need the MC340649 bit at all,
> but YMMV...
> 
> > Second, though I studied the datasheet for the 6809 microprocessor
> > carefully to make sure I did not exceed maximum current limits on
> > pins, I probably should have put buffers between the cpu signals and
> > the LEDs.  Buffers will be included in the next design.  I'm sure
> > there are other improvements that could be done as well.
> 
> Buffering would be good, if you really need those LEDs at all.  I doubt if they are particularly useful, and they probably don't make a
> great light show either -- just my $0.02...
> 
> > There are numerous notes in the schematic, however, feel free to ask
> > me or Jim at Retro Innovations any questions you may have.
> >
> > In the folder Kipper SBC v1 in my dropbox are the schematics and board
> > layout with dimensions at the following link.
> >
> > <
> > https://www.dropbox.com/sh/lhpa2j2qy78wi1u/AADQENXcZltISTHB_6_IE5oYa?d
> > l=0>
> >
> > Everyone is welcome to chime in.  I'm looking forward to our collaboration.
> > I'd like to make this first version the best it can be for what it is
> > designed to do.  Thank you all in advance for your help.  Take care my
> > friends.
> 
> Well, good luck -- maybe you will be on the right track now!
> 
> John
> --
> John W. Linville		Someday the world will need a hero, and you
> linville at tuxdriver.com			might be all we have.  Be ready.
> 
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