How can I add more outputs?
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Posts: 46,084
I recently was introduced to the basic stamp as a possible solution to a
project that I'm working on by a former electronics teacher at my school. To
get to the point, originlly the device only required 9 outputs so I was
fine, but then, I decided that I needed 25 in total. I presented this
problem to the teacher, who recommended the 74154 chip, a multiplexer, 4
input lines, 16 output linues. When I learned more about this chip however,
I found that I would have to continually send data to it in order to keep
the lines the way I wanted them. Is this the best solution, or is there a
different chip that I could, for instance shift out 4 bits to toggle the
value of a line, or even a chip that I could send 5 bits, first 4 to specify
line, next to specify high or low? The main thing I guess I'm interested in
is that it keeps the state of a particular line similarly to how the basic
stamp does. Is there a better way than a 74154?
-Randy
project that I'm working on by a former electronics teacher at my school. To
get to the point, originlly the device only required 9 outputs so I was
fine, but then, I decided that I needed 25 in total. I presented this
problem to the teacher, who recommended the 74154 chip, a multiplexer, 4
input lines, 16 output linues. When I learned more about this chip however,
I found that I would have to continually send data to it in order to keep
the lines the way I wanted them. Is this the best solution, or is there a
different chip that I could, for instance shift out 4 bits to toggle the
value of a line, or even a chip that I could send 5 bits, first 4 to specify
line, next to specify high or low? The main thing I guess I'm interested in
is that it keeps the state of a particular line similarly to how the basic
stamp does. Is there a better way than a 74154?
-Randy
Comments
state until you send another command. The 595 has 8 output lines byt can be
daisy chained to give you 16-24-36 and so on. If you need help with it let me
know.
Sid Weaver
W4EKQ
Port Richey, FL
[noparse][[/noparse]Non-text portions of this message have been removed]
>I recently was introduced to the basic stamp as a possible solution to a
>project that I'm working on by a former electronics teacher at my school. To
>get to the point, originlly the device only required 9 outputs so I was
>fine, but then, I decided that I needed 25 in total. I presented this
>problem to the teacher, who recommended the 74154 chip, a multiplexer, 4
>input lines, 16 output linues. When I learned more about this chip however,
>I found that I would have to continually send data to it in order to keep
>the lines the way I wanted them. Is this the best solution, or is there a
>different chip that I could, for instance shift out 4 bits to toggle the
>value of a line, or even a chip that I could send 5 bits, first 4 to specify
>line, next to specify high or low? The main thing I guess I'm interested in
>is that it keeps the state of a particular line similarly to how the basic
>stamp does. Is there a better way than a 74154?
>
>-Randy
Hi Randy -
You might want to look at the Philips PCF8574 which will give you 8 more
ports per chip. There is also an article in Nuts & Volts magazine which
addresses its use on the PBASIC Stamp. Sorry, I don't have the article
number at my fingertips, but someone else may have it, and chime in. The
articles can be found in the download section of the Parallax web site
<http://www.parallax.com/> or from the Nuts and Volts web site found here:
<http://www.nutsvolts.com/>. I2C may be in the title of the article, since
that's the bus structure that the Philips chip uses.
Regards,
Bruce Bates
74xx595 is great. SPI interface (I think - been a while). Can sink enough
power to run 8 leds, source is a fair bit weaker (your supposed to sink, not
source, with shift registers/io expanders anyway). The SPI interface can be
a bit of a bother compared to I2C but there are lots of stamp examples to
get you going. You need three pins plus 1 pin per '595 to use this (so 1
'595 needs 4 pins, 2 needs 5, 4 needs 7 etc)
The other, which I use exclusively now, is the PCF8574. It can't sink quite
as much as the '595 but Its great for logic level things. I use it mostly
for keypads. A nice feature is its interrupt line - if any inputs change it
signals you through a seperate pin. Sourcing power with this chip is out of
the question though, only 200uA total IIRC. You can have eight 8574s while
using only 2 stamp pins.
Original Message
From: "Randy Becker" <randy@l...>
To: "Basic Stamps List" <basicstamps@yahoogroups.com>
Sent: Friday, June 27, 2003 3:08 PM
Subject: [noparse][[/noparse]basicstamps] How can I add more outputs?
> I recently was introduced to the basic stamp as a possible solution to a
> project that I'm working on by a former electronics teacher at my school.
To
> get to the point, originlly the device only required 9 outputs so I was
> fine, but then, I decided that I needed 25 in total. I presented this
> problem to the teacher, who recommended the 74154 chip, a multiplexer, 4
> input lines, 16 output linues. When I learned more about this chip
however,
> I found that I would have to continually send data to it in order to keep
> the lines the way I wanted them. Is this the best solution, or is there a
> different chip that I could, for instance shift out 4 bits to toggle the
> value of a line, or even a chip that I could send 5 bits, first 4 to
specify
> line, next to specify high or low? The main thing I guess I'm interested
in
> is that it keeps the state of a particular line similarly to how the basic
> stamp does. Is there a better way than a 74154?
>
> -Randy
>
>
>
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>
things simple. It requires one more line than the PCF8574, but is much
easier to deal with -- especially with a stock BS2. There are code
examples on our web site. Our book, StampWorks, shows how to
daisy-chain multiple '595s for more outputs.
-- Jon Williams
-- Parallax
Original Message
From: pm [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=PbxLePq-EkcNyyu3JWZRn9bRvcdP9UXwZhiUCJhUOkOBDRd32he3fQsdtiQfH8Pcp2u5UtGa]pmeloy@s...[/url
Sent: Friday, June 27, 2003 5:53 PM
To: basicstamps@yahoogroups.com
Subject: Re: [noparse][[/noparse]basicstamps] How can I add more outputs?
There are two good options here. For slightly higher power demands, the
74xx595 is great. SPI interface (I think - been a while). Can sink
enough power to run 8 leds, source is a fair bit weaker (your supposed
to sink, not source, with shift registers/io expanders anyway). The SPI
interface can be a bit of a bother compared to I2C but there are lots of
stamp examples to get you going. You need three pins plus 1 pin per '595
to use this (so 1 '595 needs 4 pins, 2 needs 5, 4 needs 7 etc)
The other, which I use exclusively now, is the PCF8574. It can't sink
quite as much as the '595 but Its great for logic level things. I use it
mostly for keypads. A nice feature is its interrupt line - if any inputs
change it signals you through a seperate pin. Sourcing power with this
chip is out of the question though, only 200uA total IIRC. You can have
eight 8574s while using only 2 stamp pins.
Original Message
From: "Randy Becker" <randy@l...>
To: "Basic Stamps List" <basicstamps@yahoogroups.com>
Sent: Friday, June 27, 2003 3:08 PM
Subject: [noparse][[/noparse]basicstamps] How can I add more outputs?
> I recently was introduced to the basic stamp as a possible solution to
> a project that I'm working on by a former electronics teacher at my
> school.
To
> get to the point, originlly the device only required 9 outputs so I
> was fine, but then, I decided that I needed 25 in total. I presented
> this problem to the teacher, who recommended the 74154 chip, a
> multiplexer, 4 input lines, 16 output linues. When I learned more
> about this chip
however,
> I found that I would have to continually send data to it in order to
> keep the lines the way I wanted them. Is this the best solution, or is
> there a different chip that I could, for instance shift out 4 bits to
> toggle the value of a line, or even a chip that I could send 5 bits,
> first 4 to
specify
> line, next to specify high or low? The main thing I guess I'm
> interested
in
> is that it keeps the state of a particular line similarly to how the
> basic stamp does. Is there a better way than a 74154?
>
> -Randy
>
>
>
> 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.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
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Original Message
From: "Jon Williams" <jwilliams@p...>
To: <basicstamps@yahoogroups.com>
Sent: Friday, June 27, 2003 5:14 PM
Subject: RE: [noparse][[/noparse]basicstamps] How can I add more outputs?
> I've used both extensively and would recommend the 74HC595 just to keep
> things simple. It requires one more line than the PCF8574, but is much
> easier to deal with -- especially with a stock BS2. There are code
> examples on our web site. Our book, StampWorks, shows how to
> daisy-chain multiple '595s for more outputs.
>
> -- Jon Williams
> -- Parallax
>
>
Actually, now that you mention it - you dont actually need one extra pin per
extra chip do you. One way would be to use a '595 as a "chip enable
selector" and have its outputs enable up to 8 other 595's. You have to send
two SPI commands out - one to set which 595 to talk to then a second for the
actual control messages - but that makes for a whopping number of 595s -
just have to be careful not to enable too many at once and overload your
stamp [noparse]:D[/noparse]
send all the bits through the devices (one byte per device), the latch
everything at once. You only need three Stamp pins, I promise. Go to
our web site and select...
Downloads >> StampWorks Library >> Experiment 23b
It will show you what you need to know for 16 outputs -- stepping it up
to 24 or 32 is no more difficult.
-- Jon Williams
-- Parallax
Original Message
From: pm [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=co88kXb50jFm24hgdRT0tisD_LrRQMoPRGsp5Wm-qQxyNo95SHtAtbksjmiO-Ap8oDOMaNC4KZ0]pmeloy@s...[/url
Sent: Friday, June 27, 2003 8:20 PM
To: basicstamps@yahoogroups.com
Subject: Re: [noparse][[/noparse]basicstamps] How can I add more outputs?
Original Message
From: "Jon Williams" <jwilliams@p...>
To: <basicstamps@yahoogroups.com>
Sent: Friday, June 27, 2003 5:14 PM
Subject: RE: [noparse][[/noparse]basicstamps] How can I add more outputs?
> I've used both extensively and would recommend the 74HC595 just to
> keep things simple. It requires one more line than the PCF8574, but
> is much easier to deal with -- especially with a stock BS2. There are
> code examples on our web site. Our book, StampWorks, shows how to
> daisy-chain multiple '595s for more outputs.
>
> -- Jon Williams
> -- Parallax
>
>
Actually, now that you mention it - you dont actually need one extra pin
per extra chip do you. One way would be to use a '595 as a "chip enable
selector" and have its outputs enable up to 8 other 595's. You have to
send two SPI commands out - one to set which 595 to talk to then a
second for the actual control messages - but that makes for a whopping
number of 595s - just have to be careful not to enable too many at once
and overload your stamp [noparse]:D[/noparse]
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Inputs/Outputs using a single input pin.
The board is sold as a kit by www.robotstore.com
those. Or, you could use I2C, and the PCF8574.
--- In basicstamps@yahoogroups.com, "Randy Becker"
<randy@l...> wrote:
> I recently was introduced to the basic stamp as a possible
solution to a
> project that I'm working on by a former electronics teacher at
my school. To
> get to the point, originlly the device only required 9 outputs so I
was
> fine, but then, I decided that I needed 25 in total. I presented
this
> problem to the teacher, who recommended the 74154 chip, a
multiplexer, 4
> input lines, 16 output linues. When I learned more about this
chip however,
> I found that I would have to continually send data to it in order to
keep
> the lines the way I wanted them. Is this the best solution, or is
there a
> different chip that I could, for instance shift out 4 bits to toggle
the
> value of a line, or even a chip that I could send 5 bits, first 4 to
specify
> line, next to specify high or low? The main thing I guess I'm
interested in
> is that it keeps the state of a particular line similarly to how the
basic
> stamp does. Is there a better way than a 74154?
>
> -Randy
(and the PAK-III) which add I/O pins to the Stamp (or anything really).
Unlike a shift register, the I/O on the PAK can do powerful things like
pulse I/O, PWM, etc. just like Stamp I/O. This also gives you a single
level of concurrency. That is, the PAK can be doing some I/O operation
at the same time the Stamp is carrying out a different process. So you
can set the PAK to measure a pulse, for example, and it doesn't stop the
Stamp from doing what it is doing.
Details at http://www.al-williams.com/pak3.htm
Regards,
Al Williams
AWC
* NEW Kit: PC Interfacing made easy: http://www.al-williams.com/gp3.htm
>
Original Message
> From: Randy Becker [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=bcDurMQTSXHlR1LTixa_IsUccstnBSSEL1OhyTqc8q5L-qHaSWIm0l7htwH0s0I1sV6m1a0Dh_A]randy@l...[/url
> Sent: Friday, June 27, 2003 5:08 PM
> To: Basic Stamps List
> Subject: [noparse][[/noparse]basicstamps] How can I add more outputs?
>
>
> I recently was introduced to the basic stamp as a possible
> solution to a project that I'm working on by a former
> electronics teacher at my school. To get to the point,
> originlly the device only required 9 outputs so I was fine,
> but then, I decided that I needed 25 in total. I presented
> this problem to the teacher, who recommended the 74154 chip,
> a multiplexer, 4 input lines, 16 output linues. When I
> learned more about this chip however, I found that I would
> have to continually send data to it in order to keep the
> lines the way I wanted them. Is this the best solution, or is
> there a different chip that I could, for instance shift out 4
> bits to toggle the value of a line, or even a chip that I
> could send 5 bits, first 4 to specify line, next to specify
> high or low? The main thing I guess I'm interested in is that
> it keeps the state of a particular line similarly to how the
> basic stamp does. Is there a better way than a 74154?
>
> -Randy
>
>
>
> 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.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
>
this. The device basicly controls 60-watt light bulbs and is part of a much
larger project. I've already built the output portion which is triggered by
sinking the input lines. They are conveniently logicly grouped in 9 and 16
(3x3 and 5x5=9+16). This as well as the (seemingly) fairly easy interface to
the 595 (reading SW Exp 23b) are why I think that'll work best. Thanks so
much!
Oh, for this project I bought and built a BS2 OEM kit (lots of fun!) and I
need a serial connector on the outside of the box, but the pins are so close
to the edge of the board that if I use a harddrive ribbon cable to connect
the board it adds too much space to prevent the port from being attached.
Does anyone know of a good way to get a cheap 20 pin connection that won't
take up that little bit of extra space to the left? Also, what about
mounting the OEM board? the aren't any holes!
-Randy
Original Message
From: "Jon Williams" <jwilliams@p...>
To: <basicstamps@yahoogroups.com>
Sent: Friday, June 27, 2003 8:42 PM
Subject: RE: [noparse][[/noparse]basicstamps] How can I add more outputs?
> No, you can tie all the latch lines together. You'll use SHIFTOUT to
> send all the bits through the devices (one byte per device), the latch
> everything at once. You only need three Stamp pins, I promise. Go to
> our web site and select...
>
> Downloads >> StampWorks Library >> Experiment 23b
>
> It will show you what you need to know for 16 outputs -- stepping it up
> to 24 or 32 is no more difficult.
>
> -- Jon Williams
> -- Parallax
>
>
>
Original Message
> From: pm [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=_QB91OBNg9xT8rvCx0LQVAlawpWLaN47g5ZUIe1ZVX3XggNBblVuntzWvL88YoklIB15L-LUyA]pmeloy@s...[/url
> Sent: Friday, June 27, 2003 8:20 PM
> To: basicstamps@yahoogroups.com
> Subject: Re: [noparse][[/noparse]basicstamps] How can I add more outputs?
>
>
>
>
Original Message
> From: "Jon Williams" <jwilliams@p...>
> To: <basicstamps@yahoogroups.com>
> Sent: Friday, June 27, 2003 5:14 PM
> Subject: RE: [noparse][[/noparse]basicstamps] How can I add more outputs?
>
>
> > I've used both extensively and would recommend the 74HC595 just to
> > keep things simple. It requires one more line than the PCF8574, but
> > is much easier to deal with -- especially with a stock BS2. There are
>
> > code examples on our web site. Our book, StampWorks, shows how to
> > daisy-chain multiple '595s for more outputs.
> >
> > -- Jon Williams
> > -- Parallax
> >
> >
>
> Actually, now that you mention it - you dont actually need one extra pin
> per extra chip do you. One way would be to use a '595 as a "chip enable
> selector" and have its outputs enable up to 8 other 595's. You have to
> send two SPI commands out - one to set which 595 to talk to then a
> second for the actual control messages - but that makes for a whopping
> number of 595s - just have to be careful not to enable too many at once
> and overload your stamp [noparse]:D[/noparse]
>
>
>
> 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.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
>
>
> This message has been scanned by WebShield. Please report SPAM to
> abuse@p....
>
>
>
>
> 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.
>
>
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>
wrote:
> I recently was introduced to the basic stamp as a possible
solution to a
> project that I'm working on by a former electronics teacher at my
school. To
> get to the point, originlly the device only required 9 outputs so
I was
> fine, but then, I decided that I needed 25 in total. I presented
this
> problem to the teacher, who recommended the 74154 chip, a
multiplexer, 4
> input lines, 16 output linues. When I learned more about this chip
however,
While the 74154 will give you 16 outputs, and they will maintain
their state (reflecting the 4 BS2 outputs), the real problem is that
only *1* output can be active at a time. To get 8 or 16 or more
outputs that maintain their state, you will need a chip such as the
one suggested by others (74LS595). Just thought you should know why
the 74154 wouldn't be a good choice.