Led display using basic stamp (is that possible?)
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Posts: 46,084
Hi,
please help :
The problem is:
how to display 20 characters, each character has
40 leds (8x5) .
Total= 20 x 40=800 outputs
Is that posible ?
Thanks: Joe
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please help :
The problem is:
how to display 20 characters, each character has
40 leds (8x5) .
Total= 20 x 40=800 outputs
Is that posible ?
Thanks: Joe
__________________________________
Do you Yahoo!?
Yahoo! Finance: Get your refund fast by filing online.
http://taxes.yahoo.com/filing.html
Comments
please help :
The problem is:
how to display 20 characters, each character has
40 leds (8x5) .
Total= 20 x 40=800 outputs
Is that posible ?
Thanks: Joe
__________________________________
Do you Yahoo!?
Yahoo! Finance: Get your refund fast by filing online.
http://taxes.yahoo.com/filing.html
it.
-- Jon Williams
-- Applications Engineer, Parallax
-- Dallas Office
Original Message
From: Joe Terk [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=zJiIVAybk8nTRKeboU0rgOBYfwWGR-g2t10ukeU4X0GqJcu32k0tqHCOrRJySxzKnqwFs8VLEOk]joeterk@y...[/url
Sent: Monday, February 16, 2004 2:41 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Led display using basic stamp (is that possible?)
Hi,
please help :
The problem is:
how to display 20 characters, each character has
40 leds (8x5) .
Total= 20 x 40=800 outputs
Is that posible ?
Thanks: Joe
of the character bit-patterns from the
BS2, this is possible. But basically
you'll need a co-processor to remember
the data at each character position, and
refresh the LED's.
There's several ways to
do this. The typical approach is to 'scan'
through each column of LED's at a certain
rate -- typically 60 Hertz. To do that requires
hardware which can change 8 outputs, strobe a
signal low to display 8 LED's, then move on to
the next row, and do this fast enough that the
eye sees no 'flicker'. This is not hard for
a typical micro -- but probably beyond what
a BS2 can do. You'd need 100 rows, and
100 bytes (one per row). Too much. It
would be much more efficient to use a
single PIC 16F876 (which has enough SRAM)
and 6 74HCT595's for the scan pulse,
and program it in assembly.
Another approach is to have a 74HCT595 for
each row and use the 595's to 'remember'
the data. That's still a lot of '595's.
The MAX7219 can drive 64 discrete LED's
each chip, and they do the scan and
current limiting themselves. If you
were doing one chip per character,
this could be a good solution. That
would be 20 chips, but somebody still has to
load the bit patterns. If you stored the
bit patterns in EEPROM, the BS2 could
support this.
--- In basicstamps@yahoogroups.com, Joe Terk <joeterk@y...> wrote:
> Hi,
>
> please help :
>
> The problem is:
> how to display 20 characters, each character has
> 40 leds (8x5) .
>
> Total= 20 x 40=800 outputs
>
> Is that posible ?
>
> Thanks: Joe
>
>
> __________________________________
> Do you Yahoo!?
> Yahoo! Finance: Get your refund fast by filing online.
> http://taxes.yahoo.com/filing.html
Is it practical? I'm not sure.
I drive 7-segment displays which have BCD-to-7 segment decoders available
using SHIFTOUT and several shift registers (see the example and demo program
in the BASIC Stamp manual for the SHIFTOUT commeand used with a 74HC595
shift register). This requires one 8 bit shift register for 2 digits.
You could use this method for all 800 LED's. Determine which LED's have to
be on and which off; send 1's or 0's serially to the shift registers (all
800 bits!); when the data is transfered, move it to the output latch. The
upside is you could do it all with 3 I/O pins. The down side is it would
take 100 8-bit shift registers! Thus the statement questioning the
practicality.
A more practical approach would be to multiplex the display. Connect all 20
digits to one set of 5 8-bit shift registers. Then turn on each digit in
turn while loading the data for that digit into the shift registers. If you
do it fast enough, the eye is tricked into seeing all digits on all the
time. The BASIC Stamp may not be fast enough to do this, however, (I've
never tried it) especially depending on what else your program does.
Good luck.
Bill, WB8ZRN
Original Message
From: "Joe Terk" <joeterk@y...>
To: <basicstamps@yahoogroups.com>
Sent: Monday, February 16, 2004 3:52 PM
Subject: [noparse][[/noparse]basicstamps] Led display using basic stamp (is that possible?)
> Hi,
>
> please help :
>
> The problem is:
> how to display 20 characters, each character has
> 40 leds (8x5) .
>
> Total= 20 x 40=800 outputs
>
> Is that posible ?
>
> Thanks: Joe
>
>
> __________________________________
> Do you Yahoo!?
> Yahoo! Finance: Get your refund fast by filing online.
> http://taxes.yahoo.com/filing.html
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
> Yahoo! Groups Links
>
>
>
>
>
>
>
> _____________________________________________________
> This message scanned for viruses by CoreComm
>
why not [noparse]:)[/noparse]) they make for businesses once. It had 7 rows by 80 columns of
LEDs. It controlled them using multiplexing. It used 10 8-bit shift
registers, one pin of the shift register per column, so one shift register
would run 8 coloums. The sign then would go through the rows updating the
shift registers for every row. I was thinking about using this method as
well but as Bill pointed out the stamp may not be fast enough as it would
have to shift out 80 bits for every row and do it fast enough so the eye
doesn't see flicker. Additionally memory is another big hitch the stamp
would have to remember the values for every single LED. There is ways
around the memory issue with the stamp but for the speed nothing can be done
short of using a BS2P which still may not be fast enough. The sign that I
took apart was built using a Z80 CPU which is definitely more powerful then
a stamp. So like Bill said it is possible but it may be well beyond the
capabilities of one stamp to handle so it's probably not practical. I've
been meaning to investigate this for myself when I do I'll make sure to
report back to the list with what I find out.
Chris Shuster
Original Message
From: "Bill Reese" <breese@r...>
To: <basicstamps@yahoogroups.com>
Sent: Monday, February 16, 2004 6:20 PM
Subject: Re: [noparse][[/noparse]basicstamps] Led display using basic stamp (is that possible?)
> Is it possible? Yes
> Is it practical? I'm not sure.
>
> I drive 7-segment displays which have BCD-to-7 segment decoders available
> using SHIFTOUT and several shift registers (see the example and demo
program
> in the BASIC Stamp manual for the SHIFTOUT commeand used with a 74HC595
> shift register). This requires one 8 bit shift register for 2 digits.
>
> You could use this method for all 800 LED's. Determine which LED's have to
> be on and which off; send 1's or 0's serially to the shift registers (all
> 800 bits!); when the data is transfered, move it to the output latch. The
> upside is you could do it all with 3 I/O pins. The down side is it would
> take 100 8-bit shift registers! Thus the statement questioning the
> practicality.
>
> A more practical approach would be to multiplex the display. Connect all
20
> digits to one set of 5 8-bit shift registers. Then turn on each digit in
> turn while loading the data for that digit into the shift registers. If
you
> do it fast enough, the eye is tricked into seeing all digits on all the
> time. The BASIC Stamp may not be fast enough to do this, however, (I've
> never tried it) especially depending on what else your program does.
>
> Good luck.
>
> Bill, WB8ZRN
>
>
Original Message
> From: "Joe Terk" <joeterk@y...>
> To: <basicstamps@yahoogroups.com>
> Sent: Monday, February 16, 2004 3:52 PM
> Subject: [noparse][[/noparse]basicstamps] Led display using basic stamp (is that possible?)
>
>
> > Hi,
> >
> > please help :
> >
> > The problem is:
> > how to display 20 characters, each character has
> > 40 leds (8x5) .
> >
> > Total= 20 x 40=800 outputs
> >
> > Is that posible ?
> >
> > Thanks: Joe
> >
> >
> > __________________________________
> > Do you Yahoo!?
> > Yahoo! Finance: Get your refund fast by filing online.
> > http://taxes.yahoo.com/filing.html
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed. Text in the Subject
and
> Body of the message will be ignored.
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >
> > _____________________________________________________
> > This message scanned for viruses by CoreComm
> >
>
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
> Yahoo! Groups Links
>
>
>
>
>
>
http://www.adaptivedisplays.com/Pages/a_one.htm
They have an rs232 interface so the stamp would control output
at the character level. The series 300 allows for 20 characters.
The device handles the storage, power and multiplexing issues,
and your stamp runs the show.
regards peter
Original Message
From: "Chris Shuster" <cpuman3@h...>
To: <basicstamps@yahoogroups.com>
Sent: Tuesday, February 17, 2004 3:07 AM
Subject: Re: [noparse][[/noparse]basicstamps] Led display using basic stamp (is that possible?)
> I took apart one of those large LED ticker signs (it was broken so I
figures
> why not [noparse]:)[/noparse]) they make for businesses once. It had 7 rows by 80 columns of
> LEDs. It controlled them using multiplexing. It used 10 8-bit shift
> registers, one pin of the shift register per column, so one shift register
> would run 8 coloums. The sign then would go through the rows updating the
> shift registers for every row. I was thinking about using this method as
> well but as Bill pointed out the stamp may not be fast enough as it would
> have to shift out 80 bits for every row and do it fast enough so the eye
> doesn't see flicker. Additionally memory is another big hitch the stamp
> would have to remember the values for every single LED. There is ways
> around the memory issue with the stamp but for the speed nothing can be
done
> short of using a BS2P which still may not be fast enough. The sign that I
> took apart was built using a Z80 CPU which is definitely more powerful
then
> a stamp. So like Bill said it is possible but it may be well beyond the
> capabilities of one stamp to handle so it's probably not practical. I've
> been meaning to investigate this for myself when I do I'll make sure to
> report back to the list with what I find out.
>
> Chris Shuster
>
>
Original Message
> From: "Bill Reese" <breese@r...>
> To: <basicstamps@yahoogroups.com>
> Sent: Monday, February 16, 2004 6:20 PM
> Subject: Re: [noparse][[/noparse]basicstamps] Led display using basic stamp (is that
possible?)
>
>
> > Is it possible? Yes
> > Is it practical? I'm not sure.
> >
> > I drive 7-segment displays which have BCD-to-7 segment decoders
available
> > using SHIFTOUT and several shift registers (see the example and demo
> program
> > in the BASIC Stamp manual for the SHIFTOUT commeand used with a 74HC595
> > shift register). This requires one 8 bit shift register for 2 digits.
> >
> > You could use this method for all 800 LED's. Determine which LED's have
to
> > be on and which off; send 1's or 0's serially to the shift registers
(all
> > 800 bits!); when the data is transfered, move it to the output latch.
The
> > upside is you could do it all with 3 I/O pins. The down side is it would
> > take 100 8-bit shift registers! Thus the statement questioning the
> > practicality.
> >
> > A more practical approach would be to multiplex the display. Connect all
> 20
> > digits to one set of 5 8-bit shift registers. Then turn on each digit in
> > turn while loading the data for that digit into the shift registers. If
> you
> > do it fast enough, the eye is tricked into seeing all digits on all the
> > time. The BASIC Stamp may not be fast enough to do this, however, (I've
> > never tried it) especially depending on what else your program does.
> >
> > Good luck.
> >
> > Bill, WB8ZRN
> >
> >
Original Message
> > From: "Joe Terk" <joeterk@y...>
> > To: <basicstamps@yahoogroups.com>
> > Sent: Monday, February 16, 2004 3:52 PM
> > Subject: [noparse][[/noparse]basicstamps] Led display using basic stamp (is that possible?)
> >
> >
> > > Hi,
> > >
> > > please help :
> > >
> > > The problem is:
> > > how to display 20 characters, each character has
> > > 40 leds (8x5) .
> > >
> > > Total= 20 x 40=800 outputs
> > >
> > > Is that posible ?
> > >
> > > Thanks: Joe
> > >
> > >
> > > __________________________________
> > > Do you Yahoo!?
> > > Yahoo! Finance: Get your refund fast by filing online.
> > > http://taxes.yahoo.com/filing.html
> > >
> > >
> > > To UNSUBSCRIBE, just send mail to:
> > > basicstamps-unsubscribe@yahoogroups.com
> > > from the same email address that you subscribed. Text in the Subject
> and
> > Body of the message will be ignored.
> > >
> > > Yahoo! Groups Links
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > _____________________________________________________
> > > This message scanned for viruses by CoreComm
> > >
> >
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed. Text in the Subject
and
> Body of the message will be ignored.
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
> Yahoo! Groups Links
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>
>
>
>