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68HC11 Project

Started by nilesfantasy November 18, 2005
A while back I uploaded a piece of code that would interface a 68HC11 to a 7221 or 7219 LED driver, and a computer. The ZIP file is called Picktolight Demo. There is a bug in the code for the 68HC11 that does not allow displaying more than 2 characters. Since the project that I developted the code for didn't take off, I didn't work any further on troubleshooting it. I figure that perhaps you could take the clock idea and create a simple circuit that is complex at the same time. What I am saying is that you could create a clock, but instead of having the 68HC11 do the timing and display for the clock, create a small VB program that displays the time, sends the characters to the 68HC11, which in turn displays the charachters via the LED driver chips. This project would encompass subjects such as PC to 68HC11 communication, 68HC11 to LED driver interfacing, etc.

Or, instead of a clock, perhaps a Scoreboard would be more your speed. I found this project whilst working on the Pick-to-light project and the folks that worked on this project are still around. Here is the link:

http://64.233.161.104/search?qhe:uIN4yWw0TGMJ:www.messiah.edu/acdept/depthome/engineer/Projects/edr_finalreport/pdf/TeamScoreboard.pdf+68hc11+scoreboard&hl=en

Just a thought.

LF
Mark Schultz <n9xmj@n9xm...> wrote:
--- In m68HC11@m68H..., "nilesfantasy" <nilesfantasy@y...> wrote:
>
> I was wondering if anyone could suggest a simple project that could be
> conducted on the Motorola 68HC11.
...

One of the first "real" projects I did with a microcontroller was a
simple digital clock.

If you go with this idea, I'd suggest using a dedicated LED driver IC
(see http://www.maxim-ic.com for some good candidates) or a character
mode LCD module for a display. The only other hardware you'll need
(other than your micro development board) are a few pushbuttons tied
to inputs (with pull-up or pull-down resistors) that you'll use to set
the clock.

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Seems there's a fair spread of potential sophistication here.

Presuming this to be non-trivial, then any concept should have a few
special "features" provided by the availability of computing power. The
tacho idea is such an example - signal processing, but I won't butt into
the current argument.

I have been unable to find the reference, but for a digital clock, one
novel design used a dot-matrix (mini-"Times Square") display and
interpreted time in alphanumerics such as "it's nearly ten past seven".
Another concept; this kit: http://tinyurl.com/d92jq speaks for itself.

The "propeller clock" and its commercial incarnations are of
course, legion nowadays. There's a kit version on my bench (somewhere).

Many of these designs are more suited to a PIC or AVR (faster,
cheaper, smaller) and one such which is dear to my heart - but I haven't
done it yet - is the digital metronome which with a 2.5 digit display
and a few buttons would allow setting of the beat by tapping it into one
button, the corresponding rate would then be displayed and it would
proceed from there. Clearly the rate could alternately be incremented
and decremented by "up" and "down" buttons.

A *really* minimal design (12C509) - two input buttons and two
outputs, is the "ultimate" windscreen wiper controller (well OK, not the
rain-sensing one!).

--
Cheers,
Paul B.


BobGardner@BobG... wrote:

>
> In a message dated 11/18/05 4:01:53 P.M. Eastern Standard Time,
> Mike.McCarty@Mike... writes:
>
> I recommend against this. There are three problems with it
> which are, I deem, enough to make it unsuitable for the
> newbie >
> =====================
>
> HehHeh.... yeah... its a neat project tho...I bet he picks this one >


I agree. Mike is missing the point of student projects. The goal is to
demonstrate the ability to recognize and deal with a variety of
technical challenges with (hopefully) inovative ideas - not to produce a
commercially viable product. As for the demo, most students video tape
the demo beforehand in case Murphy visits during the "live" presentation.

Dave > SPONSORED LINKS
> Freescale semiconductor inc
> <http://groups.yahoo.com/gads?t=ms&k=Freescale+semiconductor+inc&w1=Freescale+semiconductor+inc&w2=Microcontrollers&w3=Pic+microcontrollers&w451+microprocessor&c=4&s6&.sig=K2HGv-zFlv5OYUv_QxIq_Q>
> Microcontrollers
> <http://groups.yahoo.com/gads?t=ms&k=Microcontrollers&w1=Freescale+semiconductor+inc&w2=Microcontrollers&w3=Pic+microcontrollers&w451+microprocessor&c=4&s6&.sig=SYHwNJjjGQXRvtt_GybT4g>
> Pic microcontrollers
> <http://groups.yahoo.com/gads?t=ms&k=Pic+microcontrollers&w1=Freescale+semiconductor+inc&w2=Microcontrollers&w3=Pic+microcontrollers&w451+microprocessor&c=4&s6&.sig=umVbbnUwsPzEzKKD_pQfUw>
>
> 8051 microprocessor
> <http://groups.yahoo.com/gads?t=ms&k51+microprocessor&w1=Freescale+semiconductor+inc&w2=Microcontrollers&w3=Pic+microcontrollers&w451+microprocessor&c=4&s6&.sig=NO-nSKjHoAlh9XtZ8LB1_A >
>
> >. >
>


Dont laugh! And Dont be Gay!

David Lincoln <davel@dave...> wrote: BobGardner@BobG... wrote:

>
> In a message dated 11/18/05 4:01:53 P.M. Eastern Standard Time,
> Mike.McCarty@Mike... writes:
>
> I recommend against this. There are three problems with it
> which are, I deem, enough to make it unsuitable for the
> newbie >
> =====================
>
> HehHeh.... yeah... its a neat project tho...I bet he picks this one >


I agree. Mike is missing the point of student projects. The goal is to
demonstrate the ability to recognize and deal with a variety of
technical challenges with (hopefully) inovative ideas - not to produce a
commercially viable product. As for the demo, most students video tape
the demo beforehand in case Murphy visits during the "live" presentation.

Dave > SPONSORED LINKS
> Freescale semiconductor inc
> <http://groups.yahoo.com/gads?t=ms&k=Freescale+semiconductor+inc&w1=Freescale+semiconductor+inc&w2=Microcontrollers&w3=Pic+microcontrollers&w451+microprocessor&c=4&s6&.sig=K2HGv-zFlv5OYUv_QxIq_Q>
> Microcontrollers
> <http://groups.yahoo.com/gads?t=ms&k=Microcontrollers&w1=Freescale+semiconductor+inc&w2=Microcontrollers&w3=Pic+microcontrollers&w451+microprocessor&c=4&s6&.sig=SYHwNJjjGQXRvtt_GybT4g>
> Pic microcontrollers
> <http://groups.yahoo.com/gads?t=ms&k=Pic+microcontrollers&w1=Freescale+semiconductor+inc&w2=Microcontrollers&w3=Pic+microcontrollers&w451+microprocessor&c=4&s6&.sig=umVbbnUwsPzEzKKD_pQfUw>
>
> 8051 microprocessor
> <http://groups.yahoo.com/gads?t=ms&k51+microprocessor&w1=Freescale+semiconductor+inc&w2=Microcontrollers&w3=Pic+microcontrollers&w451+microprocessor&c=4&s6&.sig=NO-nSKjHoAlh9XtZ8LB1_A >
>
> >. >
>

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David Lincoln wrote:
> BobGardner@BobG... wrote: >>In a message dated 11/18/05 4:01:53 P.M. Eastern Standard Time,
>>Mike.McCarty@Mike... writes:
>>
>>I recommend against this. There are three problems with it
>>which are, I deem, enough to make it unsuitable for the
>>newbie
>>
>>
>>
>>=====================
>>
>>HehHeh.... yeah... its a neat project tho...I bet he picks this one
>>
>>
> >
> I agree. Mike is missing the point of student projects. The goal is to

I have not missed anything. I note that you didn't argue against
any of the facts I presented. Also note the careful use of the
words "recommend" and "deem".

> demonstrate the ability to recognize and deal with a variety of
> technical challenges with (hopefully) inovative ideas - not to produce a
> commercially viable product. As for the demo, most students video tape

I didn't say that it was. OTOH, I realize the limitations of
students. If they take on this particular project, I suspect that
the project would work. For a half hour or so. And then mysteriously
stop working. When the AC kicked in. And the processor board
(presumably costing approximately $100 for a demonstrator,
or equivalent amounts of time to construct) would have problems
which might be beyond either the fiscal or electronic
capabilities to replace or repair. Blown voltage regulator,
probably blown uC, possibly blown 74HC573 or similar if
expanded mode, possibly blown op amp(s), possibly blown RAM
chips.

Unless you've designed a uC board with 70+V 50-100ms long pulses
applied to it, and seen what happens, then I suggest that
you not recommend others to do so.

I deem this is not a good project. You may deem it is, but I
suspect you haven't had a controller board blown on you from
being connected to an automotive supply.

One way around this would be to isolate the supply for the
uC by running it off a separate battery supply, and attach
the "battery voltage" through some heavy filtering, using say
a resistor feeding reverse connected zeners of about 24V and
then using AC coupling.

Students will make mistakes. I expect three or four in such
a project. This shouldn't also cost the students $300 to
$400 in blown uC boards.

Another issue is a safety one. Direct connections to the
battery can supply 200+ amps. True, the voltage is not
dangerous, but students probably do not know to remove
all jewelry before dealing with such a connection.
Even the "cigarette lighter" connection can supply in
excess of 10 amps. 120 W is a serious amount of power.

> the demo beforehand in case Murphy visits during the "live" presentation.
>
> Dave

Mike
--
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