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'[PIC]: propellor clock - finally'
2002\08\11@190619 by Tony Nixon

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Hi all,

Finally, I finished that propellor clock.

I got a black and white image of the Wright bothers' first take off from
the web then modified it so that it looks sepia coloured and got a high
quality print onto heavy grade photo paper. I tried to back light it,
but failed slightly due to lack of space. Oh well, it's not too bad and
I just wanted to give an "ON" indication. As the missus pointed out,
"How can you tell the time when it doesn't run all the time". Ya got to
love em :-)

Here is a GIF of it running...

http://www.bubblesoftonline.com/prop4.gif

--
Best regards

Tony

mICros
http://www.bubblesoftonline.com
spam_OUTsalesTakeThisOuTspambubblesoftonline.com

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2002\08\11@192322 by Shawn Mulligan

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It's beautiful! -Shawn

{Quote hidden}

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2002\08\11@195059 by Olin Lathrop

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> Finally, I finished that propellor clock.
>
> ...
>
> http://www.bubblesoftonline.com/prop4.gif

Nice job, Tony.  So that's what you meant by a propellor clock!

I have done something similar (rotating LEDs to make pixels), and I'm
curious how close the implementations are.  I used a 16C66.  It receives a
timing pulse from an opto interrupter once per revolution.  This is captured
by a CCP module, and the instructions per pixel calculated from that.  Timer
0 is then used to cause an interrupt when it's time to update the LEDs twice
each pixel.  Twice because the display looked stupid if the LEDs were on for
the whole pixels.  I had to match the dots caused by the discrete LEDs in
the sweep direction by having the LEDs completely off every 1/2 pixel.  The
message is stored as ASCII characters, and conversion to pixels is done on
the fly using a font table that takes up most of the program memory.  You
can see a small picture of it at
http://www.embedinc.com/ourportfolio.shtml#eyeball.

If you're willing to tell, how did you do it?  I'm mostly curious whether
convergent evolution drives these kinds of designs mostly in the same
direction, or whether there are fundametally different ways of doing this.
The way I did it seemed obvious to me, but I have no way of knowing what I
didn't think of.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

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2002\08\11@201648 by Tony Nixon

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Olin Lathrop wrote:
>
> > Finally, I finished that propellor clock.
> >
> > ...
> >
> > http://www.bubblesoftonline.com/prop4.gif
>
> Nice job, Tony.  So that's what you meant by a propellor clock!

> If you're willing to tell, how did you do it?  I'm mostly curious whether
> convergent evolution drives these kinds of designs mostly in the same
> direction, or whether there are fundametally different ways of doing this.
> The way I did it seemed obvious to me, but I have no way of knowing what I
> didn't think of.

Hi Olin,

I was going to post it as a project, but unless the builder has a lathe,
it couldn't be done my way. I have since seen a design that is a
rotating PCB with 2 brass fingers rubbing onto a fixed PCB attached to a
motor that has circular tracks as part of the PCB design which would be
easier to make.

I got the original idea from Bob Blick, but I needed a "propellor" theme
for the aero club, so I had to start from scratch.

I use a LED sensor to sense each rotation and this triggers the RB0INT
interrupt. It just outputs each column of pixel data for a few uS from a
RAM buffer which is loaded with new data each time the minutes change.
Here's the simple IRQ code. The LEDs are driven directly from PORTB.

       movlw Digit_HR          ; FSR = 1st display data byte
       movwf FSR
DispLoop        movf INDF,W
       movwf PORTB
       incf FSR

       movlw 0x75              ; pixel delay
       movwf HSCount
HSLoop  decfsz HSCount
       goto HSLoop

       movlw Digit_HR + d'31'  ; 31 bytes per display field
       xorwf FSR,W
       btfss STATUS,Z
       goto DispLoop

       movlw 0xFF              ; display = off
       movwf PORTB

I didn't want to hack a motor for this design like Bob did, so I just
fed AC to the rotating PCB via slip rings. This supplies power as well
as a 50Hz signal for time keeping. The 16F627 is working with it's
internal clock source.

The tricky part was setting the time with external buttons when all I
had was a 2 wire 50Hz AC supply to work with. I ended up switching a
series diode in and out of the input feed which half wave rectifies the
power supply. The PIC detects this drop in frequency and this is used as
a signal that a "switch" is pressed. Half wave is still ok to power the
circuit although the LED brightness drops slightly.

To keep the project free of buttons which could have made the project
look messy, I used Q-Prox sensors to detect finger touches on the glass
panel.

I have seen a rotary display like on you web page and they look quite
good.

The simulator is also interesting, some members of my aero club is
building a sophisticated rig right now.

--
Best regards

Tony

mICros
http://www.bubblesoftonline.com
salesspamKILLspambubblesoftonline.com

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2002\08\12@131745 by Robert E. Griffith

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It looks great!

--BobG

-----Original Message-----
From: pic microcontroller discussion list [.....PICLISTKILLspamspam.....MITVMA.MIT.EDU]On
Behalf Of Tony Nixon
Sent: Sunday, August 11, 2002 7:05 PM
To: EraseMEPICLISTspam_OUTspamTakeThisOuTMITVMA.MIT.EDU
Subject: [PIC]: propellor clock - finally

Hi all,

Finally, I finished that propellor clock.

I got a black and white image of the Wright bothers' first take off from
the web then modified it so that it looks sepia coloured and got a high
quality print onto heavy grade photo paper. I tried to back light it,
but failed slightly due to lack of space. Oh well, it's not too bad and
I just wanted to give an "ON" indication. As the missus pointed out,
"How can you tell the time when it doesn't run all the time". Ya got to
love em :-)

Here is a GIF of it running...

http://www.bubblesoftonline.com/prop4.gif

--
Best regards

Tony

mICros
http://www.bubblesoftonline.com
salesspamspam_OUTbubblesoftonline.com

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2002\08\12@133224 by Pic Dude

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Tony,

This is really awesome!  Congrats!
Perhaps you can appease "the missus" by having a "chime" every
half hour or so, and let it fire itself up for a minute.

Cheers,
-Neil.



> {Original Message removed}

2002\08\12@194421 by Tom Handley

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   Tony, that really is first class. Outstanding job!

   - Tom

At 16:05 11-08-02, Tony wrote:
{Quote hidden}

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