[Coco] Kip's Single Board Computer

[John W. Linville]

Well, that seems fine.  But I think a simple capacitor will do the job... :-)

John

On Tue, Sep 15, 2015 at 12:34:59PM -0500, Dave Philipsen wrote:
> So I just sent Jim an offer to send a couple of DS1233-10 chips.  The chip
> basically holds a CPU in reset for 350ms after the power supply comes up and
> is stable.  I have used probably 1,500-2,000 of these over the years in a
> little 68HC11 board I designed about 20 years ago:
> 
> http://www.davebiz.com/HC11.jpg
> 
> You can see the DS1233-10 in the upper left corner of the board next to the
> oscillator chip.
> 
> Dave
> 
> 
> On , John W. Linville wrote:
> >On Tue, Sep 15, 2015 at 12:06:04PM -0500, RETRO Innovations wrote:
> >>On 9/15/2015 11:49 AM, John W. Linville wrote:
> >>>On Tue, Sep 15, 2015 at 12:15:15PM -0400, RETRO Innovations wrote:
> >>>>    The new board, as it were (it's getting less new by the month) is Kip's
> >>>>    take on Searle's 6 IC 6809.  His is 8, and offers some interesting
> >>>>    enhancement options.
> >>>>
> >>>>    But, when I try to bring the board up, I'm struggling:
> >>>>
> >>>>      * there is no signal on Q or E.
> >>>>      * Nothing of interest on the crystal pins (though my Tek could be
> >>>>        interfering with the feedback).
> >>>>      * I took the CPU off the board, breadboarded with HALT and RESET
> >>>>        high, crystal and caps installed, and still no Q or E.  I tried a
> >>>>        known working 6809 from my SuperPET, and nothing.
> >>>>
> >>>>    I'm new to 6809/6309, so I am not sure where to start.  I am sure once
> >>>>    I get the CPU running, the rest will be quick work, but the fact that I
> >>>>    can't seem to get a 6809 by itself to generate Q and E bothers me and
> >>>>    lowers my confidence that the board is ready to be debugged.
> >>>>
> >>>>    Kip, send the man a board.  I'll buy it for him.
> >>>>
> >>>>    Jim
> >>>I'm fairly certain that the clock problem is caused by the lack of
> >>>RC circuit on the RESET^ line, as I described in my earlier note...do
> >>>I get a board too? :-)
> >>>
> >>>John
> >>Happy to buy you one.  My time is precious, and saving 2-3 hours on the
> >>bench is worth quite a bit at this stage in my life.
> >>
> >>So, for the 6809 noob, is there a data sheet page I should reference for
> >>the
> >>correct cap/resistor values?
> >
> >So, the RESET^ reference on page 6 points to Figure 7 (which is on
> >page 8).  There it refers to the initial low time as "tRC".
> >
> >Near the bottom of the chart in Figure 1 (on page 3) it shows a maximum
> >value for tRC as 100mS.  Oddly, no minimum is listed.
> >
> >Referring to the Simon6809 schematic, it looks like he is using an R
> >of 10Kohm and a C of 10uF.  That should put you right at that 100mS
> >"maximum", but it works fine.
> >
> >Anyway, I would suggest something approaching 100mS.  Since Kip seems
> >to have a 2.2Kohm pull-up on RESET^, maybe a 47uF capacitor from
> >there to ground?  Of course, that ignores the R10 and LED path...you
> >may have to try some different cap values if that doesn't work...
> >
> >>I remember the reset controller from my 68hc11 days.  Man, Motorola was
> >>picky on reset.
> >
> >:-)
> >
> >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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-- 
John W. Linville		Someday the world will need a hero, and you
linville at tuxdriver.com			might be all we have.  Be ready.