# Sprinkler pump controller

J

#### [email protected]

I've had this idea for a while but don't know exactly how to go
about it. I'm thinking of a micro controller of some sort but I
haven't worked with micro controllers and not sure which one would be
best for this project. I also want to make this project into
something that I could use on a resume, something . I am an
electronics engineering technician (AS-ET).

This is the basics of what I have now. I have a water retention
system (55 gallon drums manifold together) that has an MPXV501GP (1.45
PSI) to detect the water level in the system. I have a rain sensor
mounted on the gutter.

What I want to be able to do is to turn on the sprinkler pump
after it hasn't rained for a number of days. I also want the pump to
come on when the system level goes above a narrow high window and off
again below that same window. I also want it to shut down the pump if
it goes below a bottom window and able to come back on above that
lower window when it hasn't rained for the preset number of days.
Upper and lower windows could be detected with 2 op amps for the
upper and 2 for the lower. I've done something similar to this before
but was a number of years ago and I can't find the documentation as to
what I did and parts I used. They probably don't make those parts
anymore anyway.

The newest data book I have is a TI linear volume 3 from 1992. Do
they have hard copy data books any more or they all on CD?

J

#### John Barrett

I've had this idea for a while but don't know exactly how to go
about it. I'm thinking of a micro controller of some sort but I
haven't worked with micro controllers and not sure which one would be
best for this project. I also want to make this project into
something that I could use on a resume, something . I am an
electronics engineering technician (AS-ET).

This is the basics of what I have now. I have a water retention
system (55 gallon drums manifold together) that has an MPXV501GP (1.45
PSI) to detect the water level in the system. I have a rain sensor
mounted on the gutter.

What I want to be able to do is to turn on the sprinkler pump
after it hasn't rained for a number of days. I also want the pump to
come on when the system level goes above a narrow high window and off
again below that same window. I also want it to shut down the pump if
it goes below a bottom window and able to come back on above that
lower window when it hasn't rained for the preset number of days.
Upper and lower windows could be detected with 2 op amps for the
upper and 2 for the lower. I've done something similar to this before
but was a number of years ago and I can't find the documentation as to
what I did and parts I used. They probably don't make those parts
anymore anyway.

The newest data book I have is a TI linear volume 3 from 1992. Do
they have hard copy data books any more or they all on CD?

PIC or Atmel -- I recommend the Atmel because of the readily available free
C development tools and a reasonably inexpensive development kit that
handles most of their chips. ($250 or so for the dev kit, or you can find programmers for less than$50 and go right to circuit) I dont know about PIC
dev kits but I'm sure they are out there, as are cheap programmers

So its really more a question of what languages do you know, and what dev
tools are out there for those languages, rather than what chip is best....
even the smallest 8 pin PIC will handle the application you described with
I/O to spare (maybe use the left over pins for some status LEDs or a serial
interface back to your PC for monitoring and remote control)

R

I've had this idea for a while but don't know exactly how to go
about it. I'm thinking of a micro controller of some sort but I
haven't worked with micro controllers and not sure which one would be
best for this project. I also want to make this project into
something that I could use on a resume, something . I am an
electronics engineering technician (AS-ET).

This is the basics of what I have now. I have a water retention
system (55 gallon drums manifold together) that has an MPXV501GP (1.45
PSI) to detect the water level in the system. I have a rain sensor
mounted on the gutter.

What I want to be able to do is to turn on the sprinkler pump
after it hasn't rained for a number of days. I also want the pump to
come on when the system level goes above a narrow high window and off
again below that same window. I also want it to shut down the pump if
it goes below a bottom window and able to come back on above that
lower window when it hasn't rained for the preset number of days.
Upper and lower windows could be detected with 2 op amps for the
upper and 2 for the lower. I've done something similar to this before
but was a number of years ago and I can't find the documentation as to
what I did and parts I used. They probably don't make those parts
anymore anyway.

A small PLC would probably be simpler, but I don't think you are looking
for dimpler. I'd look for an eval board to start with. Almost any
small micro. AVR, MSP, ARM just about any would fit the bill.
The newest data book I have is a TI linear volume 3 from 1992. Do
they have hard copy data books any more or they all on CD?

Data books have become rare, although still nice to have. CDs, are
thankfully, even rarer.

Robert

H

#### Homer J Simpson

What I want to be able to do is to turn on the sprinkler pump
after it hasn't rained for a number of days.

I've seen systems that measured the moisture level in the soil and ran the
pumps accordingly. Popular in Australia I believe.

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J

#### [email protected]

I've seen systems that measured the moisture level in the soil and ran the
pumps accordingly. Popular in Australia I believe.

What kind of sensor do they use? I might want to use that as
another condition to be examined by the micro controller I really
don't want to buy a pre-manufactured system, I want to design and
build one for educational and potential job related experience.

J

#### [email protected]

A small PLC would probably be simpler, but I don't think you are looking
for dimpler. I'd look for an eval board to start with. Almost any
small micro. AVR, MSP, ARM just about any would fit the bill.
I guess that I need to go to their web sites to find out their
specifications and if I think they would be a good learning tool.
What is a popular one that would have the most relevance to many
designs?
Data books have become rare, although still nice to have. CDs, are
thankfully, even rarer.

Robert

Do some companies still publish data books? How does one go
browsing for parts these days?

B

#### [email protected]

What kind of sensor do they use? I might want to use that as
another condition to be examined by the micro controller I really
don't want to buy a pre-manufactured system, I want to design and
build one for educational and potential job related experience.

I don't know, but a google search on "soil moisture sensors" threw up
a bunch of interesting sites. Here are two of them.

http://www.delta-t.co.uk/groups.html?group2005092332137&gclid=CLKQ0Nyo_ooCFSYbEAodPBRZFg

which looks as if they rely on measuring conductivity - almost
certainly with an AC-excited bridge.

http://www.cropinfo.net/AnnualReports/2001/Popsensortest01.htm

which compares six different sensors - I didn't get much insight out
of it, but I didn't read it carefully.

F

#### Fred Bloggs

I've had this idea for a while but don't know exactly how to go
about it. I'm thinking of a micro controller of some sort but I
haven't worked with micro controllers and not sure which one would be
best for this project. I also want to make this project into
something that I could use on a resume, something .

The first order of business in a project like this is to FULLY
understand the PROCESS you are trying to control. In your case this
means you must find out more about agricultural irrigation and the
various considerations that go into controlling its application from an
agricultural perspective. You don't just jump in with a bunch of minutia
about some "manifolded" buckets, pressure sensors, sprinklers, and other
odds and ends that you can kluge together to realize your hazy and
unsatisfactory idea of what should be good enough. I will give a hint
and tell you right now that there is no such thing as an irrigation
controller that works based on a "preset" number of days since last
rainfall- that strategy is absurd to the point of warranting severe
condemnation. You need to know 1) how much did it rain, 2) weather
conditions following so as to stress the transpiration rate of the
crops, 3) the soil moisture requirements of said crops relative to the
integration of the estimated transpiration rate as a function of stage
into plant growth development cycle, 4) most favorable time of day and
location to apply water, sprinkling is one of the most inefficient means
BTW, 5) soil type insofar as water absorption and retention rates,
6)...and host of other parameters related to *agriculture*. It is only
*after* you have developed a *thorough* understanding of these
requirements and a *thorough* understanding of the various doctrinal
control methodology that have proved successful in practice can you even
buckets, pressure sensors, and what-nots. Get it?

R

I guess that I need to go to their web sites to find out their
specifications and if I think they would be a good learning tool.
What is a popular one that would have the most relevance to many
designs?

That depends on the kind of designs you are looking at. Personally I've
defaulted to ARM variants as my starting point, they are readily
available with a lot of variety and reasonable inexpensive in small
quantities. They are also big enough in terms of available memory and
processing power to takle quite a range of problems. foe specific jobs
other processors may be a better choice to get some desired chara
cteristic or peripheral (physical size, high res A/D, low cost, some
specific obscure I/O etc...) I don't much like PICs but that's a
personal quirk, some swear by them, some at them.
Do some companies still publish data books? How does one go
browsing for parts these days?

There are a few. Deutsch come to mind as one whose data book is much
better than their web site, in their case mainly because of very poor
PDFs. Most of the data books I get now seem to be from connector
companies. For semiconductors you generally need to beg reps to get
Data books, Sometimes they are available, often they are not. The last
I got on a micro was a few years ago for a 80C196 variant, the rep had a
couple printed out for me.

Browsing for parts is a matter of browsing web sites of the
manufacturers and, especially if you are using small quantities,
checking a few on-line distributers for stock.

Robert

P

#### Peter Bennett

Do some companies still publish data books? How does one go
browsing for parts these days?

Most manufacturers have all their datasheets, selection guides, and
app notes available on-line. Searching a distributor's website, such
as Digikey or Mouser, can give you a good idea of what parts are
actually available.

A google search for IC part number +datasheet will generally locate a
datasheet (although you will often get several pay datasheet sites
listed before the manufacturer's site)

--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
new newsgroup users info : http://vancouver-webpages.com/nnq
GPS and NMEA info: http://vancouver-webpages.com/peter

J

#### [email protected]

The first order of business in a project like this is to FULLY
understand the PROCESS you are trying to control. In your case this
means you must find out more about agricultural irrigation and the
various considerations that go into controlling its application from an
agricultural perspective. You don't just jump in with a bunch of minutia
about some "manifolded" buckets, pressure sensors, sprinklers, and other
odds and ends that you can kluge together to realize your hazy and
unsatisfactory idea of what should be good enough. I will give a hint
and tell you right now that there is no such thing as an irrigation
controller that works based on a "preset" number of days since last
rainfall- that strategy is absurd to the point of warranting severe
condemnation. You need to know 1) how much did it rain, 2) weather
conditions following so as to stress the transpiration rate of the
crops, 3) the soil moisture requirements of said crops relative to the
integration of the estimated transpiration rate as a function of stage
into plant growth development cycle, 4) most favorable time of day and
location to apply water, sprinkling is one of the most inefficient means
BTW, 5) soil type insofar as water absorption and retention rates,
6)...and host of other parameters related to *agriculture*. It is only
*after* you have developed a *thorough* understanding of these
requirements and a *thorough* understanding of the various doctrinal
control methodology that have proved successful in practice can you even
buckets, pressure sensors, and what-nots. Get it?

What I get is that you don't thoroughly understand that the more
important consideration at this time is to learn how to utilize a
micro controller and build a system that functions as intended. Your
other considerations are of merit but this is for a single residential
application, as in my house, not some large scale farming operation.
It is a lot more practical than some of these other micro
controller projects I have seen posted here by some under-graduate
college students that are assigned their by their instructor or
professor to build some circuit that counts the revolutions of some
shaft or whatnot over a given amount of time. Maybe I'll want to
incorporate those other aspects you mentioned above at a later date
but for now I just want to controllably water the lawn and learn how
to use and program a micro controller.

H

#### Homer J Simpson

What kind of sensor do they use?

Just a couple of probes in the ground. Stainless would be best I assume.

E

#### ehsjr

I've had this idea for a while but don't know exactly how to go
about it. I'm thinking of a micro controller of some sort but I
haven't worked with micro controllers and not sure which one would be
best for this project. I also want to make this project into
something that I could use on a resume, something . I am an
electronics engineering technician (AS-ET).

This is the basics of what I have now. I have a water retention
system (55 gallon drums manifold together) that has an MPXV501GP (1.45
PSI) to detect the water level in the system. I have a rain sensor
mounted on the gutter.

What I want to be able to do is to turn on the sprinkler pump
after it hasn't rained for a number of days. I also want the pump to
come on when the system level goes above a narrow high window and off
again below that same window. I also want it to shut down the pump if
it goes below a bottom window and able to come back on above that
lower window when it hasn't rained for the preset number of days.
Upper and lower windows could be detected with 2 op amps for the
upper and 2 for the lower. I've done something similar to this before
but was a number of years ago and I can't find the documentation as to
what I did and parts I used. They probably don't make those parts
anymore anyway.

The newest data book I have is a TI linear volume 3 from 1992. Do
they have hard copy data books any more or they all on CD?

"Program" it first at the functional level, before choosing
the ucontroller. Two conditions do not "go through" the
ucontroller: When the low window bottom sensor is dry,
the pump is off regardless of any other conditions; when the
high window high sensor is wet, the pump is on regardless
of any other conditions. That said, you still might want
to have the uc look at them for errors, like the low window
low sensor dry but the othere window sensors wet. Once you have
laid out all the functions you want you should be in a better
position to pick the uc. But it really doesn't matter, as
you indicated that you haven't worked with them.

So, what you really want is someone to provide a complete
solution, with the uc already chosen and the code written,
or someone with experience to tell you which uc to use so
that you can then learn how to use that particular uc
family. That experienced person will be better able to
meet your needs after you have spelled them out. For example,
you did not address resetting the timer, error checking
the sensors, what to do if the pump is running and it starts
raining, whether the timer needs to run during a power failure,
what the power on reset state should be and who knows what else.

I'm having a hard time figuring out how this project
demonstrates the need for a uc, but I think you could
demonstrate the parts cost advantage of one.

I'll show a hardware solution below. The purpose is
really background to show that the person reading the
resume may think "why in the hell is he showing such
a simple use of a uc, when so much more could be done?"

Excluding the timer, a simple hardware solution is a couple
of relays. I'll draw the comparator outputs as switches (saves
drawing the op amps) All switches made when wet.

Your rain sensor (RS - on when wet) :

/
+ ---o o---+---> timer start on break (-)
RS |
[R]
|
Gnd --------+

Your low window level top of window (TW) and bottom of
window (BW) sensors (on when wet):

/
+---o o---o--- < Low Relay 1 point
| BW ^---+
| |
| / |
+ ---+---o o----------+
TW |
[Low Relay]
|
Gnd -------------------+

When the tank is filling, BW closes first as the
level rises. When the water reaches the top
of the window, TW closes and the relay energizes.
It stays energized, if the water level drops, until
BW opens.

Your high window level top of window (TW) and bottom
of window (BW) sensors (on when wet):

/
+---o o---o--- < High Relay 1 point
| BW ^---+
| |
| / |
+ ---+---o o----------+-------< from timer output
TW |
[High Relay]
|
Gnd -------------------+

Operates the same as the bottom window sensors.
In addition, the relay can be controlled via the
timer. That meets your condition of the pump
operating when the timer calls for it, regardless
of the status of the upper window sensors.

AC ----- < Low Relay 2 Point
^------+
|
+--- High Relay 2 Point
+--^
|
[Pump]
|
AC -----------+

The point of all that is to show that the uc
is not providing a whole bunch of function that
mandates its use over hardware. You want the
resume to sell a product - you - to the company.

Maybe it would be sufficient for your project to use
the uc as the basis for your timer - I don't know. It
seems to me a waste of uc power to use it only as a
timer in this. Neither the hardware nor software solution
can be given until timer reset is defined, but the
hardware solution might be a counter like a CD4060
and support components or maybe cascaded ICM7242's.
I think it would be a better project if you could do
all the "thinking" with a uc - and show enough need
for "thinking" that the person reading the resume
is impressed. As stated, your project doesn't do that,
in my opinion.

selectable on times like 4 hours every other day
or so many minutes daily or once a week or whatever,
sensor logical error checking, maybe an "it's been
too dry for too long" alarm to a human operator, etc.
The more practical flexibility you put into it, the
better.

Ed

J

#### John Fields

Just a couple of probes in the ground. Stainless would be best I assume.

Iridium.

B

#### [email protected]

Platinum is usually preferred for conductivity sensors, but soil
conductivity is pretty low, so stainless steel would probably be good
enough - the layer of chromium oxide (or whatever) that stops
stainless steel from rusting has a rather unpredictable range of
thicknesses and resistance, but the additional resistance of the oxide
layer is usually negligibly small when you are measuring soil
conductivity.

R

I guess that I need to go to their web sites to find out their
specifications and if I think they would be a good learning tool.
What is a popular one that would have the most relevance to many
designs?

That depends on the kind of designs you are looking at. Personally I've
defaulted to ARM variants as my starting point, they are readily
available with a lot of variety and reasonable inexpensive in small
quantities. They are also big enough in terms of available memory and
processing power to takle quite a range of problems. foe specific jobs
other processors may be a better choice to get some desired chara
cteristic or peripheral (physical size, high res A/D, low cost, some
specific obscure I/O etc...) I don't much like PICs but that's a
personal quirk, some swear by them, some at them.
Do some companies still publish data books? How does one go
browsing for parts these days?

There are a few. Deutsch come to mind as one whose data book is much
better than their web site, in their case mainly because of very poor
PDFs. Most of the data books I get now seem to be from connector
companies. For semiconductors you generally need to beg reps to get
Data books, Sometimes they are available, often they are not. The last
I got on a micro was a few years ago for a 80C196 variant, the rep had a
couple printed out for me.

Browsing for parts is a matter of browsing web sites of the
manufacturers and, especially if you are using small quantities,
checking a few on-line distributers for stock.

Robert

F

#### Fred Bloggs

What I get is that you don't thoroughly understand that the more
important consideration at this time is [for me] to learn how to utilize a
micro controller and build a system that functions as intended.

Maybe for a self-centered narcissist it is more important, but, in the
real world, the individual engineer/technician is subordinate to the
goal of product creation to the point of being a completely
insignificant non-entity of the lowest order. Don't plan on impressing

M

#### mpm

I've had this idea for a while but don't know exactly how to go

Personally, you can cobble up a one-off sprinkler doo-hickey and I'm
sure it'd be real nice.
But you can perhaps accomplish the same thing by using a Programmable
Logic Controller.

Go to AutomationDirect.com and take a look at the DL5 and DL6 models.
(There are plenty of others to choose from).

This will get you some good, rock-solid hardware to play with.
Lots of options, etc... Inputs/outputs comms, .. (and probably for
less  than you would otherwise spend in development)

As for the resume, well, these things are usually programmed in
And these days, that's a weird-enough term to catch someone's
attention.
If they're actually paying attention that is.

I'm afraid have to agree with Fred's comments (above) that the days
of impressing anyone with your engineering resume are not what they
used to be...

-mpm

J

#### [email protected]

What I get is that you don't thoroughly understand that the more
important consideration at this time is [for me] to learn how to utilize a
micro controller and build a system that functions as intended.

Maybe for a self-centered narcissist it is more important, but, in the
real world, the individual engineer/technician is subordinate to the
goal of product creation to the point of being a completely
insignificant non-entity of the lowest order. Don't plan on impressing

I certainly don't expect to impress you with much of anything. I
would guess that a bunch of college students, year after year,
devising the same circuit that counts the revolutions of a shaft to be
of greater import and practical than someone showing a little
imagination and building something different.

J

#### [email protected]

That depends on the kind of designs you are looking at. Personally I've
defaulted to ARM variants as my starting point, they are readily
available with a lot of variety and reasonable inexpensive in small
quantities. They are also big enough in terms of available memory and
processing power to takle quite a range of problems. foe specific jobs
other processors may be a better choice to get some desired chara
cteristic or peripheral (physical size, high res A/D, low cost, some
specific obscure I/O etc...) I don't much like PICs but that's a
personal quirk, some swear by them, some at them.

Have you used the Keil kits and are their eval boards
interchangeable between kits? If I get one starter kit with a certain
chip eval board, can I just get another eval board for another chip
and it work?
There are a few. Deutsch come to mind as one whose data book is much
better than their web site, in their case mainly because of very poor
PDFs. Most of the data books I get now seem to be from connector
companies. For semiconductors you generally need to beg reps to get
Data books, Sometimes they are available, often they are not. The last
I got on a micro was a few years ago for a 80C196 variant, the rep had a
couple printed out for me.

Browsing for parts is a matter of browsing web sites of the
manufacturers and, especially if you are using small quantities,
checking a few on-line distributers for stock.

Robert

My favorites are DigiKey and Mouser.

E
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