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by jsobota
Sun Jan 26, 2014 10:46 pm
Forum: HATs and other add-ons
Topic: Gertduino and RPi Model B Rev. 1
Replies: 4
Views: 3064

Re: Gertduino and RPi Model B Rev. 1

Thank you all for your replies, I just ordered my GertDuino.
by jsobota
Wed Nov 27, 2013 6:22 pm
Forum: HATs and other add-ons
Topic: Gertduino and RPi Model B Rev. 1
Replies: 4
Views: 3064

Gertduino and RPi Model B Rev. 1

Has anybody tested Gertduino with Raspberry Pi Model B Rev. 1 (the one without mounting holes)? Is it compatible? Thanks.
by jsobota
Sun Oct 13, 2013 11:15 pm
Forum: Automation, sensing and robotics
Topic: Desktop PC Power Control
Replies: 23
Views: 13616

Re: Desktop PC Power Control

The relay board is just fine. Even if it is marketed as Arduino board (which is 5V) the pins controlling the relays are at approx 3V in the default state and you have to pull them low (or connect them to GND) to "fire" the relay (i.e. it has inverted behaviour). There are PC817 optocouplers so it is...
by jsobota
Sat Oct 05, 2013 1:34 pm
Forum: Automation, sensing and robotics
Topic: 24VAC to 5VDC Conversion
Replies: 18
Views: 19659

Re: 24VAC to 5VDC Conversion

I'm using this one based on KIS-3R33 and it works great:
http://www.ebay.com/itm/Kis-3r33s-DC-DC ... 51aa89e8b3
by jsobota
Tue Oct 01, 2013 11:10 pm
Forum: Automation, sensing and robotics
Topic: Turning a Raspberry Pi into a PLC - Software Problems
Replies: 17
Views: 13970

Re: Turning a Raspberry Pi into a PLC - Software Problems

You might want to check the third option, the REX Control System. Programming is done using FBD. If you are interested, visit the thread http://www.raspberrypi.org/phpBB3/viewt ... 37&t=55811 It is not mentioned there but it supports Modbus over RS485 and RS232 too.
by jsobota
Tue Oct 01, 2013 9:40 pm
Forum: Automation, sensing and robotics
Topic: Home automation with RPI for control wired "things"
Replies: 43
Views: 24993

Re: Home automation with RPI for control wired "things"

@crystal13: both of your plans seem reasonable, my only advice is to use a proper USB wifi device as @halhertani mentioned. I am using Edimax EW-7811Un if I need wifi on RasPi. I have prepared a silly example showing 2 RasPis exchanging data via ethernet. Prior to reading further please see the wiri...
by jsobota
Mon Sep 30, 2013 11:24 am
Forum: Automation, sensing and robotics
Topic: Controlling my central heating
Replies: 16
Views: 7384

Re: Controlling my central heating

@lucdig: how do you deal with the fact that the output voltage of the Pi GPIO is 3.3V, and the relay board that you bought works at 5V? Did you buy any other additional element or you use Pi+Arduino? The relay board is just fine. Even if it is marketed as Arduino board (which is 5V) the pins control...
by jsobota
Fri Sep 27, 2013 3:00 pm
Forum: Automation, sensing and robotics
Topic: Controlling my central heating
Replies: 16
Views: 7384

Re: Controlling my central heating

How about using a photoresistor to pull one of the GPIOs low when the light switches on?
by jsobota
Fri Sep 27, 2013 2:21 pm
Forum: Automation, sensing and robotics
Topic: Home automation with RPI for control wired "things"
Replies: 43
Views: 24993

Re: Home automation with RPI for control wired "things"

@crystal13: I will study it. So with this schema I can command the RP2 and Arduino+Eth_Shield via webserver (that is on RP1), right? What I should understand is how the RPi2 and Arduino+Eth_Shield can respond to the webserver of RPi1. Is there a database where the RPi and Arduino will insert their d...
by jsobota
Tue Sep 24, 2013 3:08 pm
Forum: Automation, sensing and robotics
Topic: Home automation with RPI for control wired "things"
Replies: 43
Views: 24993

Re: Home automation with RPI for control wired "things"

One diagram might be worth 1000 words, see the rough sketch of the topology I'm talking about. Hope it helps.
by jsobota
Tue Sep 24, 2013 12:40 pm
Forum: Automation, sensing and robotics
Topic: Home automation with RPI for control wired "things"
Replies: 43
Views: 24993

Re: Home automation with RPI for control wired "things"

OK, to clarify things: I2C and SPI are meant for master/slave connection, no discussion about it. What I meant with "master" and "slave" in the webserver context was that the RPi1 running the webserver can not only display all the data it reads from its own SPI or I2C slaves but it can also poll dat...
by jsobota
Tue Sep 24, 2013 11:43 am
Forum: Automation, sensing and robotics
Topic: Home automation with RPI for control wired "things"
Replies: 43
Views: 24993

Re: Home automation with RPI for control wired "things"

You can use I2C analog-to-digital converters to read e.g. light intensity, you can use I2C 1-wire gateway to read e.g. temperatures from DS18B20 thermometers, etc. Or you can use one Arduino to read all these sensors and let it report the data to the RPi.
by jsobota
Tue Sep 24, 2013 9:32 am
Forum: Automation, sensing and robotics
Topic: Home automation with RPI for control wired "things"
Replies: 43
Views: 24993

Re: Home automation with RPI for control wired "things"

You understand it correctly, I meant connecting the RPis via home router (or switch). The use of Arduinos is always possible. But you did not mention any analog signals in your initial post so we are coming back to my first reply - think about all the measured signals and controlled devices first, T...
by jsobota
Mon Sep 23, 2013 7:59 pm
Forum: Automation, sensing and robotics
Topic: Home automation with RPI for control wired "things"
Replies: 43
Views: 24993

Re: Home automation with RPI for control wired "things"

SPI is meant for communication between various devices over short distances, it is used mostly on a single PCB.
For communication between 2 or more RPis, I would use the onboard Ethernet.
by jsobota
Thu Sep 19, 2013 10:53 am
Forum: Automation, sensing and robotics
Topic: Home automation with RPI for control wired "things"
Replies: 43
Views: 24993

Re: Home automation with RPI for control wired "things"

No, each RPi is running its own tasks and algorithms so each of them can work standalone. The "master-slave" relationship was meant only for the purposes of the webserver. E.g. the "slave" RPi will control the temperature in one room and it will report the current temperature to the "master" RPi to ...
by jsobota
Wed Sep 18, 2013 9:15 am
Forum: Automation, sensing and robotics
Topic: Home automation with RPI for control wired "things"
Replies: 43
Views: 24993

Re: Home automation with RPI for control wired "things"

Unless you use additional hardware, the Arduino and Raspberry Pi must be relatively close to each other (you can connect them via USB or I2C). The decentralized system can be built, one RPi will serve as a "master" with a webser running and the other RPis will be "slaves" who will exchange data with...
by jsobota
Tue Sep 17, 2013 2:54 pm
Forum: Automation, sensing and robotics
Topic: Home automation with RPI for control wired "things"
Replies: 43
Views: 24993

Re: Home automation with RPI for control wired "things"

How many lights and other devices are you planning? With at least 2 GPIO for every light (1 for the relay, 1 or more for button(s) in the room) you'll run out of GPIOs on the RPi soon. That's why the Arduino comes in handy, especially the MEGA2560 with its 70 GPIOs.

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