ichabod
Posts: 5
Joined: Wed Jan 29, 2014 8:08 pm

Using RPI as a controller

Wed Jan 29, 2014 8:35 pm

How many on off valves can I control with the RPI?
what can I do to control 8 to 15?

I will need to control them Via GUI buttons.

thank you
Ichabod

User avatar
FLYFISH TECHNOLOGIES
Posts: 1750
Joined: Thu Oct 03, 2013 7:48 am
Location: Ljubljana, Slovenia
Contact: Website

Re: Using RPI as a controller

Wed Jan 29, 2014 8:57 pm

Hi,
ichabod wrote:How many on off valves can I control with the RPI?
A lot... really a lot.
Few thousand inputs and outputs can be controlled with one RasPi even without black magic.
ichabod wrote:what can I do to control 8 to 15?
You can simply put things together... as said, no black magic is needed. ;-)
ichabod wrote:I will need to control them Via GUI buttons.
Uncle Google is your friend.


Best wishes, Ivan Zilic.
Running out of GPIO pins and/or need to read analog values?
Solution: http://www.flyfish-tech.com/FF32

ichabod
Posts: 5
Joined: Wed Jan 29, 2014 8:08 pm

Re: Using RPI as a controller

Wed Jan 29, 2014 9:03 pm

Wait no black magic? that's a letdown....

Anyway I understand that I can control a ton of valves with the RPI but I want to know how many I can control with out any expansions. (just using the GPIO's on the RPI)

thanks and sorry for the newb question.
-Ichabod

User avatar
FLYFISH TECHNOLOGIES
Posts: 1750
Joined: Thu Oct 03, 2013 7:48 am
Location: Ljubljana, Slovenia
Contact: Website

Re: Using RPI as a controller

Wed Jan 29, 2014 9:06 pm

Hi,
ichabod wrote:I want to know how many I can control with out any expansions. (just using the GPIO's on the RPI)
Most likely none, due to current limitations. Valves are not small loads (in terms of GPIO capabilities).


Best wishes, Ivan Zilic.
Running out of GPIO pins and/or need to read analog values?
Solution: http://www.flyfish-tech.com/FF32

User avatar
Richard-TX
Posts: 1549
Joined: Tue May 28, 2013 3:24 pm
Location: North Texas

Re: Using RPI as a controller

Wed Jan 29, 2014 9:15 pm

If you mean by addressing the GPIO pins as I-O ports, then not many. Now if you use the I2C bus which is part of the GPIO, then the maximum number of i-o ports runs up into the 2000+ range.
Richard
Doing Unix since 1985.
The 9-25-2013 image of Wheezy can be found at:
http://downloads.raspberrypi.org/raspbian/images/raspbian-2013-09-27/2013-09-25-wheezy-raspbian.zip

ichabod
Posts: 5
Joined: Wed Jan 29, 2014 8:08 pm

Re: Using RPI as a controller

Wed Jan 29, 2014 9:50 pm

https://projects.drogon.net/raspberry-pi/wiringpi/
"The I2C and SPI interfaces can also be used a general purpose I/O pins when not being used in their bus modes, and the UART pins can also be used if you reboot with the serial console disabled, giving a grand total of 8 + 2 + 5 + 2 = 17 I/O pins."

Does the above Quote mean I can control 17 devices with the RPI GPIO's? or better yet how many I/O's does it take to control a on/off valve?

Thank you
-Ichabod

User avatar
joan
Posts: 14998
Joined: Thu Jul 05, 2012 5:09 pm
Location: UK

Re: Using RPI as a controller

Wed Jan 29, 2014 9:53 pm

Later models have 21 usable gpios.

Have you considered sharing the details of the valves you want to control?

User avatar
DougieLawson
Posts: 39602
Joined: Sun Jun 16, 2013 11:19 pm
Location: A small cave in deepest darkest Basingstoke, UK
Contact: Website Twitter

Re: Using RPI as a controller

Wed Jan 29, 2014 9:56 pm

joan wrote:Later models have 21 usable gpios.
Only if you're brave enough to solder some headers into P5 at an angle so they don't block other connectors.
Note: Any requirement to use a crystal ball or mind reading will result in me ignoring your question.

Criticising any questions is banned on this forum.

Any DMs sent on Twitter will be answered next month.
All fake doctors are on my foes list.

User avatar
joan
Posts: 14998
Joined: Thu Jul 05, 2012 5:09 pm
Location: UK

Re: Using RPI as a controller

Wed Jan 29, 2014 9:59 pm

DougieLawson wrote:
joan wrote:Later models have 21 usable gpios.
Only if you're brave enough to solder some headers into P5 at an angle so they don't block other connectors.
I soldered header pins to the underside of the board (as I think is the suggested location). The fact I made a pig's ear of it was down to my lack of soldering skills. They work though.

User avatar
DougieLawson
Posts: 39602
Joined: Sun Jun 16, 2013 11:19 pm
Location: A small cave in deepest darkest Basingstoke, UK
Contact: Website Twitter

Re: Using RPI as a controller

Wed Jan 29, 2014 10:06 pm

I may go with female to male dupont wires, solder in the male end. Don't know if I'm brave enough.
Note: Any requirement to use a crystal ball or mind reading will result in me ignoring your question.

Criticising any questions is banned on this forum.

Any DMs sent on Twitter will be answered next month.
All fake doctors are on my foes list.

steve-tmq
Posts: 8
Joined: Thu Nov 01, 2012 10:53 pm

Re: Using RPI as a controller

Thu Jan 30, 2014 8:00 am

Richard-TX wrote:If you mean by addressing the GPIO pins as I-O ports, then not many. Now if you use the I2C bus which is part of the GPIO, then the maximum number of i-o ports runs up into the 2000+ range.
For simple on/off, open/closed operation I don't agree there are the 17 GPIO pins are not buffered so you need some sort of buffering interface and may be some logic and this is where some knowlege of binary is usfull, 1 pin controls 1 thing on or off but 2 pins can control 3 things 3 pins can control 7 things and so on.....

8 pins controls 255 things

and so but the more pins you use the more logic chips you need.

Thats a start point (I have not got time today but will get back to this is asked.)

jamesh
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 26868
Joined: Sat Jul 30, 2011 7:41 pm

Re: Using RPI as a controller

Thu Jan 30, 2014 9:33 am

steve-tmq wrote:
Richard-TX wrote:If you mean by addressing the GPIO pins as I-O ports, then not many. Now if you use the I2C bus which is part of the GPIO, then the maximum number of i-o ports runs up into the 2000+ range.
For simple on/off, open/closed operation I don't agree there are the 17 GPIO pins are not buffered so you need some sort of buffering interface and may be some logic and this is where some knowlege of binary is usfull, 1 pin controls 1 thing on or off but 2 pins can control 3 things 3 pins can control 7 things and so on.....

8 pins controls 255 things

and so but the more pins you use the more logic chips you need.

Thats a start point (I have not got time today but will get back to this is asked.)
With 8 GPIO's you only have 8 INDEPENDENT on/offs. Unless you add lots of of extra logic, and use some pins as an ID, others as a command. Is that what you are getting at? But 2 pins cannot control three devices. It can control 2, and 3 pins can control 4, 4 pins 8. Going to be nasty with timing though. I'd use another pin to disable actions whilst the other pins are being changed.

But to the OP - the GPIO's are not powerful enough to drive a solenoid, so you are going to need extra circuitry.
Principal Software Engineer at Raspberry Pi (Trading) Ltd.
Contrary to popular belief, humorous signatures are allowed.
I've been saying "Mucho" to my Spanish friend a lot more lately. It means a lot to him.

LLMoon
Posts: 1
Joined: Thu Jan 30, 2014 6:50 pm

Re: Using RPI as a controller

Thu Jan 30, 2014 7:03 pm

The OpenSprinkler Pi project may of interest to you. It can control multiple irrigation valves, can daisy chain as many boards as you need to expand your system. There are several open source control applications written for the hardware, including one in Python. I have been using this for months with good success.

http://rayshobby.net/?page_id=5816

Return to “Automation, sensing and robotics”