My winter project is a microcontroller to ventilate and water my
greenhouse/high tunnel. Parallax has a sale on controllers with free
shipping through tomorrow. I plan on using Opto 22 boards and IO blocks for
this project. Parallax makes a module just for this:
http://www.parallax.com/StoreSearchR...9/Default.aspx

(parallax part number 27945 if link above breaks)

I did a count this morning and this is no where near enough IO. Parallax
makes a 40 pin stamp with 32 IO that would work. But they don't make the
above module for it. I don't want to paint myself into a corner. Should I
look at building a custom 27945 module for the 40 pin stamp? (I don't
normally do this kind of work) Or is it no big deal to use two stamps and
link them to communicate? Other ideas?

Karl

On Sun, 03 Jan 2010 09:29:58 -0500, Karl Townsend wrote:

My winter project is a microcontroller to ventilate and water my
greenhouse/high tunnel. Parallax has a sale on controllers with free
shipping through tomorrow. I plan on using Opto 22 boards and IO blocks
for this project. Parallax makes a module just for this:
http://www.parallax.com/StoreSearchR...tSearch/27945/
List/0/SortField/4/ProductID/289/Default.aspx

(parallax part number 27945 if link above breaks)

I did a count this morning and this is no where near enough IO. Parallax
makes a 40 pin stamp with 32 IO that would work. But they don't make the
above module for it. I don't want to paint myself into a corner. Should
I look at building a custom 27945 module for the 40 pin stamp? (I don't
normally do this kind of work) Or is it no big deal to use two stamps
and link them to communicate? Other ideas?

Karl

If you've got some mileage under your belt with communications protocols,
and if the language doesn't hold the capabilities of the chip too far
away from you, it _should_ be no big deal to have them talk.

Now count the 'ifs', and tell me if you're comfortable.

Perhaps the best thing to do (if Steamer doesn't already know the answer
better than I do) is to Google around a bit for someone who's done this.

From a systems engineering perspective, all else being equal, you're much
better off with one processor doing one job. If this module was
available for a 40-pin basic stamp it'd win hands down.

If you can get two modules talking, and if the I/O works out that you can
have one in charge of ventilation and one in charge of irrigation, that
should minimize the need for communication. Alternately you could have
one doing all the thinking, and the other one (or two) that's just a dumb
slave.

But I think the first thing I'd do, if I were in your shoes but with my
shop and capabilities, would be to see if I could make an adapter cable
(or cable adapter) between one 40-pin module and two of those clever I/O
modules. _If_ they are 'dumb', and pretty much just provide a plain old
interface between the basic stamp and the outside world, without any
programming or fancy dances, then you should be able to do this fairly
easily. I'd say "with parts from Radio Shack", but I'm not sure you can
get all the bits any more. If this is as easy as it could be, it'd be
the hands-down winner.

--
www.wescottdesign.com

"Karl Townsend" wrote in message
news.com...
My winter project is a microcontroller to ventilate and water my
greenhouse/high tunnel. Parallax has a sale on controllers with free
shipping through tomorrow. I plan on using Opto 22 boards and IO blocks
for this project. Parallax makes a module just for this:
http://www.parallax.com/StoreSearchR...9/Default.aspx

(parallax part number 27945 if link above breaks)

I did a count this morning and this is no where near enough IO. Parallax
makes a 40 pin stamp with 32 IO that would work. But they don't make the
above module for it. I don't want to paint myself into a corner. Should I
look at building a custom 27945 module for the 40 pin stamp? (I don't
normally do this kind of work) Or is it no big deal to use two stamps and
link them to communicate? Other ideas?

Karl


How much I/O do you need? Motor up/down takes 2, limit switches take 2, and
2 for thermostat or serial temperature sensor. Then if you have an operator
interface you can get a serial LCD and 4 inputs for select up/down, 1 for
Enter, 1 for Back (or Esc). Parallax (among others) also sells a ULN2803A
chip that can drive 8 external relays up to 50VDC 1/2A, complete with built
in diodes for inductive loads.

I bought a PIC32 starter kit from Digi-Key (Microchip has them for same
price), has a lot of I/O, 512K program memory, 32K ram, and a optimizing C
compiler with a 64K limit, all for $49.

http://www.microchip.com/stellent/id...ame =en532453


RogerN

On Jan 3, 12:13*pm, "RogerN" wrote:
"Karl Townsend" wrote in message
...

I bought a PIC32 starter kit from Digi-Key (Microchip has them for same
price), has a lot of I/O, 512K program memory, 32K ram, and a optimizing C
compiler with a 64K limit, all for $49.

http://www.microchip.com/stellent/id...GET_PAGE&nodeI....

RogerN

No A/D on that chip?

SMbus or I2C are good for simple 2 pin communications between
devices.
http://www.maxim-ic.com/app-notes/index.mvp/id/476

The receiver can use clock \_ edges to latch data and doesn't need to
sync very well to transmit timing.

jsw

"Jim Wilkins" wrote in message
...
On Jan 3, 12:13 pm, "RogerN" wrote:
"Karl Townsend" wrote in message
...

I bought a PIC32 starter kit from Digi-Key (Microchip has them for same
price), has a lot of I/O, 512K program memory, 32K ram, and a optimizing C
compiler with a 64K limit, all for $49.

http://www.microchip.com/stellent/id...GET_PAGE&nodeI...

RogerN
/
/No A/D on that chip?
/
/SMbus or I2C are good for simple 2 pin communications between
/devices.
/http://www.maxim-ic.com/app-notes/index.mvp/id/476
/
/The receiver can use clock \_ edges to latch data and doesn't need to
/sync very well to transmit timing.
/
/jsw


It has 16 channel of 10 bit A/D. It's listed to have 85 I/O but I know a
few are used for programming, debugging, 3 LED's and 3 PushButtons. You
could probably have 16 channels of analog and still have over 50 Digital I/O
left.

I bought some chips to play with on my Basic Stamp board, I tried out the
LTC1298 A/D converter and it works fine.

RogerN

How much I/O do you need? Motor up/down takes 2, limit switches take 2,
and 2 for thermostat or serial temperature sensor. Then if you have an
operator interface you can get a serial LCD and 4 inputs for select
up/down, 1 for Enter, 1 for Back (or Esc). Parallax (among others) also
sells a ULN2803A chip that can drive 8 external relays up to 50VDC 1/2A,
complete with built in diodes for inductive loads.

I also installed a 1/rev contact to detect/count motor movement on each
motor. There are four of these motors total for a total of 20 IO here . I
also sense outside temp in addition to two inside temps and want to leave
room for a wind velocity sensor (future) - four more. Then there will be two
soil moisuture sensors and a water pump - three more. I'll need a couple or
four for an LCD read panel. I'd use any extras for a small operator
interface to do things like open or close everything. From experience, I
know to leave room for more IO, always seem to need it.

I'm not aware of this ULN2903A chip, I'll look into it




I bought a PIC32 starter kit from Digi-Key (Microchip has them for same
price), has a lot of I/O, 512K program memory, 32K ram, and a optimizing C
compiler with a 64K limit, all for $49.


Basic stamp is easy to program and well documented. I'm not at all
unconfortable with it. I feel just the opposite about working with C or
assembler. Plus, I'd be on my own for driving an Opto 22 board.

Karl

On Jan 3, 1:17*pm, "Karl Townsend"
wrote:
...
I also installed a 1/rev contact to detect/count motor movement on each
motor. There are four of these motors total for a total of 20 IO here . I
also sense outside temp in addition to two inside temps and want to leave
room for a wind velocity sensor (future) - four more. Then there will be two
soil moisuture sensors and a water pump - three more. *...

Karl

With all those things to poll I'd be wary of motor sensors that
required timing measurements.

jsw

On Sun, 03 Jan 2010 13:17:52 -0500, Karl Townsend wrote:

How much I/O do you need? Motor up/down takes 2, limit switches take
2, and 2 for thermostat or serial temperature sensor. Then if you have
an operator interface you can get a serial LCD and 4 inputs for select
up/down, 1 for Enter, 1 for Back (or Esc). Parallax (among others)
also sells a ULN2803A chip that can drive 8 external relays up to 50VDC
1/2A, complete with built in diodes for inductive loads.

I also installed a 1/rev contact to detect/count motor movement on each
motor. There are four of these motors total for a total of 20 IO here .
I also sense outside temp in addition to two inside temps and want to
leave room for a wind velocity sensor (future) - four more. Then there
will be two soil moisuture sensors and a water pump - three more. I'll
need a couple or four for an LCD read panel. I'd use any extras for a
small operator interface to do things like open or close everything.
From experience, I know to leave room for more IO, always seem to need
it.

I'm not aware of this ULN2903A chip, I'll look into it




I bought a PIC32 starter kit from Digi-Key (Microchip has them for same
price), has a lot of I/O, 512K program memory, 32K ram, and a
optimizing C compiler with a 64K limit, all for $49.


Basic stamp is easy to program and well documented. I'm not at all
unconfortable with it. I feel just the opposite about working with C or
assembler. Plus, I'd be on my own for driving an Opto 22 board.

Karl

If you have the $$ to be extravagant with processors, use one per motor
and have them all talk on an RS-485 bus (assuming you can easily get set
up with RS-485 hardware).

Or don't -- it's how I'd design the system if I were going to sell it,
but half-duplex networking can be a bitch to get working the first time.

If I were anywhere close I'd offer to drop by and help out, but IIRC
you're in Wisconsin or Michigan or some other place influenced by large
amounts of fresh water and generally flat land.

--
www.wescottdesign.com

On Sun, 03 Jan 2010 20:04:54 -0600, Tim Wescott wrote:

On Sun, 03 Jan 2010 13:17:52 -0500, Karl Townsend wrote:

How much I/O do you need? Motor up/down takes 2, limit switches take
2, and 2 for thermostat or serial temperature sensor. Then if you
have an operator interface you can get a serial LCD and 4 inputs for
select up/down, 1 for Enter, 1 for Back (or Esc). Parallax (among
others) also sells a ULN2803A chip that can drive 8 external relays up
to 50VDC 1/2A, complete with built in diodes for inductive loads.

I also installed a 1/rev contact to detect/count motor movement on each
motor. There are four of these motors total for a total of 20 IO here .
I also sense outside temp in addition to two inside temps and want to
leave room for a wind velocity sensor (future) - four more. Then there
will be two soil moisuture sensors and a water pump - three more. I'll
need a couple or four for an LCD read panel. I'd use any extras for a
small operator interface to do things like open or close everything.
From experience, I know to leave room for more IO, always seem to need
it.

I'm not aware of this ULN2903A chip, I'll look into it




I bought a PIC32 starter kit from Digi-Key (Microchip has them for
same price), has a lot of I/O, 512K program memory, 32K ram, and a
optimizing C compiler with a 64K limit, all for $49.


Basic stamp is easy to program and well documented. I'm not at all
unconfortable with it. I feel just the opposite about working with C or
assembler. Plus, I'd be on my own for driving an Opto 22 board.

Karl

If you have the $$ to be extravagant with processors, use one per motor
and have them all talk on an RS-485 bus (assuming you can easily get set
up with RS-485 hardware).

Or don't -- it's how I'd design the system if I were going to sell it,
but half-duplex networking can be a bitch to get working the first time.

If I were anywhere close I'd offer to drop by and help out, but IIRC
you're in Wisconsin or Michigan or some other place influenced by large
amounts of fresh water and generally flat land.

Or or or -- if you have the serial ports available, have a master with an
RS-232 out that constantly broadcasts target positions for all the motors
& whatnot, then a slave on each motor or whatnot. Then it's just single-
way and you won't be dashing yourself on the rocks of half-duplex
protocol development after hearing the siren song of two-wire
communication.

--
www.wescottdesign.com

I'd run the complete opposite direction, Tim.

What projects like this need is a Kim-1 with a BASIC interpreter in ROM,
along with a P-coded application (also in ROM).

Or an 8 Mhz XT running DOS.


As an aside,

If the Operating System could be considered the Engine that runs the computer
then by Microsoft's example everything from a weed eater to a 787 would have
a gigawatt nuclear power plant running it.

Everything else would be run by Cox .049 model airplane motors.

"Karl Townsend" wrote in message
anews.com...
How much I/O do you need? Motor up/down takes 2, limit switches take 2,
and 2 for thermostat or serial temperature sensor. Then if you have an
operator interface you can get a serial LCD and 4 inputs for select
up/down, 1 for Enter, 1 for Back (or Esc). Parallax (among others) also
sells a ULN2803A chip that can drive 8 external relays up to 50VDC 1/2A,
complete with built in diodes for inductive loads.

I also installed a 1/rev contact to detect/count motor movement on each
motor. There are four of these motors total for a total of 20 IO here . I
also sense outside temp in addition to two inside temps and want to leave
room for a wind velocity sensor (future) - four more. Then there will be
two soil moisuture sensors and a water pump - three more. I'll need a
couple or four for an LCD read panel. I'd use any extras for a small
operator interface to do things like open or close everything. From
experience, I know to leave room for more IO, always seem to need it.

I'm not aware of this ULN2903A chip, I'll look into it




I bought a PIC32 starter kit from Digi-Key (Microchip has them for same
price), has a lot of I/O, 512K program memory, 32K ram, and a optimizing
C compiler with a 64K limit, all for $49.


Basic stamp is easy to program and well documented. I'm not at all
unconfortable with it. I feel just the opposite about working with C or
assembler. Plus, I'd be on my own for driving an Opto 22 board.

Karl


It would probably be a good idea for you to develop your application with
the Basic Stamps and after you get it like you want, you can work on getting
it to run on a $7 PIC microcontroller and get some circuit boards made. A
lot of the opto 22 modules are TTL compatible and I believe would work
directly with the Basic Stamp. The ULN2803A chip I mentioned has 8
Darlington transistor drives for $1.50, that could drive your external loads
up to 50V 1/2A.

I've seen a lot of bad examples of programming for the Basic Stamp. The
programs are well written but they make the Stamp only do one thing at a
time. I got a Boe Bot for Christmas and am rewriting one of the example
programs to run more like a PLC program.

For more I/O, you can use something like buffer chips for inputs and latches
for outputs and a multiplexer to enable what you want to address at that
time. For example, perhaps an address of 1 would give you I/O for motor 1,
address 2 for motor 2, etc. .. addresses 0,5,6,& 7 could all be used for
temperature and/or operator interface. So, on a 16 I/O PIC you can have 64
I/O without much trouble.

I'm also pretty sure that it's easy to communicate stamp to stamp. Shift in
on one and shift out on another, or serial in on one and serial out on the
other.

RogerN

Karl Townsend wrote:
My winter project is a microcontroller to ventilate and water my
greenhouse/high tunnel. Parallax has a sale on controllers with free
shipping through tomorrow. I plan on using Opto 22 boards and IO blocks for
this project. Parallax makes a module just for this:
http://www.parallax.com/StoreSearchR...9/Default.aspx

(parallax part number 27945 if link above breaks)

I did a count this morning and this is no where near enough IO. Parallax
makes a 40 pin stamp with 32 IO that would work. But they don't make the
above module for it. I don't want to paint myself into a corner. Should I
look at building a custom 27945 module for the 40 pin stamp? (I don't
normally do this kind of work) Or is it no big deal to use two stamps and
link them to communicate? Other ideas?

Karl






Some alternatives to look at as well, Karl.


Eagle 50 - starting below $50
http://micromint.com/index.php/SBC/eagle-50.html

RTC180 Zylog Z180 with ROM monitor or BASIC180 - $288
http://micromint.com/index.php/RTC/rtc180.html

RTCv25 16 bit 8086 compatible - Under $500
http://micromint.com/index.php/RTC/rtcv25.html


Or, something considerably more retro?
A brand new 1 megahertz (COUNT IT!) Kim One compatable SBC - $99
http://www.brielcomputers.com/micro-KIM.html

THIS is the kind of thing I was talking about earlier.


--

Richard Lamb
http://www.home.earthlink.net/~cavelamb/


"The clock of life is wound but once, and no man has the power
to tell just when the hands will stop, at late or early hour...
Now is the only time you own. Live, love, toil with a will.
Place no faith in time. For the clock may soon be still."

On 2010-01-03, Karl Townsend wrote:
My winter project is a microcontroller to ventilate and water my
greenhouse/high tunnel. Parallax has a sale on controllers with free
shipping through tomorrow. I plan on using Opto 22 boards and IO blocks for
this project. Parallax makes a module just for this:
http://www.parallax.com/StoreSearchR...9/Default.aspx

(parallax part number 27945 if link above breaks)

I did a count this morning and this is no where near enough IO. Parallax
makes a 40 pin stamp with 32 IO that would work. But they don't make the
above module for it.

Well ... the Opto 22 boards which I have have a maximum of 24
I/O channels -- in part because it is fed through a 50-pin cable
(power ground, +5V, and a signal-ground pair with each channel, so a
long cable will have a ground between any two signal lines to reduce
the chance of noise coupling from one line to another.

You would need two 50-pin ribbon cables to handle the 32 I/Os
which you want, and that would typically go to two Opto 22 boards so you
have easy access to the screw terminals for each I/O channel.

I don't want to paint myself into a corner. Should I
look at building a custom 27945 module for the 40 pin stamp? (I don't
normally do this kind of work) Or is it no big deal to use two stamps and
link them to communicate? Other ideas?

I would go for the latter approach. This has the advantage of
reducing the load on any one stamp. You simply have to define some kind
of I/O protocol for the communication between two stamps and make one
the master and the other the slave. Or -- perhaps -- make one handle
all outputs and one handle all inputs for monitoring results.

Good Luck,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On Sun, 3 Jan 2010 09:29:58 -0500, "Karl Townsend"
wrote:

My winter project is a microcontroller to ventilate and water my
greenhouse/high tunnel. Parallax has a sale on controllers with free
shipping through tomorrow. I plan on using Opto 22 boards and IO blocks for
this project. Parallax makes a module just for this:
http://www.parallax.com/StoreSearchR...9/Default.aspx

(parallax part number 27945 if link above breaks)

I did a count this morning and this is no where near enough IO. Parallax
makes a 40 pin stamp with 32 IO that would work. But they don't make the
above module for it. I don't want to paint myself into a corner. Should I
look at building a custom 27945 module for the 40 pin stamp? (I don't
normally do this kind of work) Or is it no big deal to use two stamps and
link them to communicate? Other ideas?

Karl

If you're comfortable that the 40-pin stamp would meet all other
criteria, namely has enough I/O and you feel able to program it in
BASIC, I wouldn't worry about the module. We can cook up an
interface between stamp I/O and opto-22.

Don Foreman wrote:
On Sun, 3 Jan 2010 09:29:58 -0500, "Karl Townsend"
wrote:

My winter project is a microcontroller to ventilate and water my
greenhouse/high tunnel. Parallax has a sale on controllers with free
shipping through tomorrow. I plan on using Opto 22 boards and IO blocks for
this project. Parallax makes a module just for this:
http://www.parallax.com/StoreSearchR...9/Default.aspx

(parallax part number 27945 if link above breaks)

I did a count this morning and this is no where near enough IO. Parallax
makes a 40 pin stamp with 32 IO that would work. But they don't make the
above module for it. I don't want to paint myself into a corner. Should I
look at building a custom 27945 module for the 40 pin stamp? (I don't
normally do this kind of work) Or is it no big deal to use two stamps and
link them to communicate? Other ideas?

Karl

If you're comfortable that the 40-pin stamp would meet all other
criteria, namely has enough I/O and you feel able to program it in
BASIC, I wouldn't worry about the module. We can cook up an
interface between stamp I/O and opto-22.



Nothing to that...

http://www.opto22.com/site/solidstaterelays.aspx

120 volt 10 amp - $14
http://www.opto22.com/site/pr_detail...=4&item=120A10



--

Richard Lamb
http://www.home.earthlink.net/~cavelamb/


"The clock of life is wound but once, and no man has the power
to tell just when the hands will stop, at late or early hour...
Now is the only time you own. Live, love, toil with a will.
Place no faith in time. For the clock may soon be still."

If you're comfortable that the 40-pin stamp would meet all other
criteria, namely has enough I/O and you feel able to program it in
BASIC, I wouldn't worry about the module. We can cook up an
interface between stamp I/O and opto-22.

Thanks for the offer. I ordered the stock items with the 16 IO stamp so I
can write and debug the program while down here. I have one of the four DC
gear motor units running. Should keep me busy for a few months.

Karl

On Tue, 05 Jan 2010 06:31:42 -0500, Karl Townsend wrote:

If you're comfortable that the 40-pin stamp would meet all other
criteria, namely has enough I/O and you feel able to program it in
BASIC, I wouldn't worry about the module. We can cook up an interface
between stamp I/O and opto-22.

Thanks for the offer. I ordered the stock items with the 16 IO stamp so
I can write and debug the program while down here. I have one of the
four DC gear motor units running. Should keep me busy for a few months.

Karl

I was going to suggest that, but I didn't know how much $$ you wanted to
spend.

One of the facets of designing with microprocessors is that they're so
damn flexible you find yourself standing in a sea of options, often with
no horizon in sight. It's why I've been schizoid in my advise to you.
It can easily become a problem if you let yourself get paralyzed by
trying to find the "best" way to go.

Fortunately, there are usually a ton of routes to success. It sounds
like you've chosen one arbitrarily and are starting to trudge down it --
good. "Working well but not perfect" is usually better than "not
working, but it'll be perfect once I -- oh! gotta change that!".

--
www.wescottdesign.com

Fortunately, there are usually a ton of routes to success. It sounds
like you've chosen one arbitrarily and are starting to trudge down it --
good. "Working well but not perfect" is usually better than "not
working, but it'll be perfect once I -- oh! gotta change that!".

Right on. AND I'll know how to do it right after I've done it the other way.
Plus, I've got a history of always looking down at the sparkies (EEs). Real
engineers always ran the project and delegated this work. My main function
was to ask, "why aren't you done yet?" and, "We need this additional
function". I guess this little job is payback.

Karl

On Wed, 06 Jan 2010 07:40:07 -0500, Karl Townsend wrote:

Fortunately, there are usually a ton of routes to success. It sounds
like you've chosen one arbitrarily and are starting to trudge down it
-- good. "Working well but not perfect" is usually better than "not
working, but it'll be perfect once I -- oh! gotta change that!".

Right on. AND I'll know how to do it right after I've done it the other
way. Plus, I've got a history of always looking down at the sparkies
(EEs). Real engineers always ran the project and delegated this work.
My main function was to ask, "why aren't you done yet?" and, "We need
this additional function". I guess this little job is payback.

Karl

Karl, if your sorting puts EE's and "real" engineers in disjoint sets I'm
not sure that I like you any more.

What sort of engineer is "real" to you, and what traumatic experience did
you have in your youth at the hands of an EE?

--
www.wescottdesign.com

"Karl Townsend" wrote in message
news.com...
My winter project is a microcontroller to ventilate and water my
greenhouse/high tunnel. Parallax has a sale on controllers with free
shipping through tomorrow. I plan on using Opto 22 boards and IO blocks
for this project. Parallax makes a module just for this:
http://www.parallax.com/StoreSearchR...9/Default.aspx

(parallax part number 27945 if link above breaks)

I did a count this morning and this is no where near enough IO. Parallax
makes a 40 pin stamp with 32 IO that would work. But they don't make the
above module for it. I don't want to paint myself into a corner. Should I
look at building a custom 27945 module for the 40 pin stamp? (I don't
normally do this kind of work) Or is it no big deal to use two stamps and
link them to communicate? Other ideas?

Karl


I've been doing some work on using a PIC microcontroller to send and receive
serial data to work with Opto22 boards. So far what I'm working on is
compatible with the 50 pin header boards from 8 I/O to 24 I/O, the 32 I/O
board has a different pinout on its header. I think I can read/write the 24
I/O points, plus communication, plus have an in circuit programming and
debugging port, all with a 40 pin PIC microcontroller.

I plan to have the PIC preprogrammed as a serial I/O board to work with
Basic Stamps, PC's or whatever else has a serial port. Most of what I've
done so far has to do with the schematic and board layout, connector
pinouts, and hardware for the project. I'm far enough along now with
hardware design that I need to build a prototype on a breadboard and start
developing and testing the software.

This board should be addressable either in hardware or software, meaning 2
pins from the Basic Stamp could be used for 24, 48, 72, 96,... I/O points,
you could have 6,144 I/O points with an 8 bit address and 24 I/O per module,
but the update wouldn't be very fast ;-)

And.. The PIC microcontroller on this I/O expander board would be
programmable to turn the Opto22 board into a stand alone PLC type
controller.

RogerN