[Coco] Kip's Single Board Computer

Tue Sep 15 14:03:38 EDT 2015

nice board
Mathieu

On Tue, Sep 15, 2015 at 2:00 PM, Dave Philipsen <dave at davebiz.com> wrote:
> Yep, it probably will.  The beauty of the 'reset' chip is that it
> continuously monitors VCC for an out-of-range value and will put the CPU
> back in reset if it finds that.  A lot of times what causes a CPU to 'lock
> up' is some dirty supply voltage that cause the something abnormal to show
> up on the data/address lines and then the CPU takes a hike to la-la land.
> This chip is like a power supply watchdog.  It also conditions a reset
> button input because, as you probably know, mechanical switches can be
> noisy/bouncy.
>
> Here's a photo of a more recent revision of the board that I did with
> onboard 5v regulator and a power supply barrel connector.  The 'HC11 runs at
> 4 MHz bus speed, has full 16-bit external address bus, buffered data lines,
> some decoded chip selects, internal 1K SRAM, internal 512-byte EEPROM,
> serial port, SPI port.  The board has all of the signals brought out to
> expansion connectors, the reset chip, a 16 MHz oscillator, RS232 port, power
> LED. socket for RTC and external EEPROM, 27C256 EPROM socket, etc.  If
> anyone's interested in playing around with one or building it from scratch I
> could make up some documentation for it along with a basic monitor in EPROM.
> I think I still have quite a few bare boards floating around that I would
> sell for cheap.  And, it's a tried and tested design.  As I said, I produce
> somewhere in the neighborhood of 1,000-1,500 of these and they're all still
> running now.
>
> http://www.davebiz.com/HC11-new.jpg
>
> Dave Philipsen
>
>
>
>
> On , John W. Linville wrote:
>>
>> 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.
>>>
>>> --
>>> Coco mailing list
>>> Coco at maltedmedia.com
>>> https://pairlist5.pair.net/mailman/listinfo/coco
>>
>>
>> --
>> John W. Linville                Someday the world will need a hero, and
>> you
>> linville at tuxdriver.com                  might be all we have.  Be ready.
>
>
> --
> Coco mailing list
> Coco at maltedmedia.com
> https://pairlist5.pair.net/mailman/listinfo/coco


-- 
A te quaeso, sicut in Aeneidos libro quarto Aeneas, elocutus
desiderium erigendi suum obeliscum in templo Venereo Didonis, ab ea
quaesivit, tuae domi an meae?