[Coco] Kip's Single Board Computer

[Dave Philipsen]

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.