5 replies to this topic

[Wayneio]

Hi there,

 

I am thinking of purchasing a netduino plus 2, with the aim of refreshing my old A-level electronics knowledge. I am an average C# coder, so that side of things is fine, but my electronics knowledge is rather rusty, and so before I buy, I would like to know if there are tutorials that can help me with my first project idea.

 

I have a blind on my window instead of curtains, but in front of it, I have desk and TV etc, so it's rather difficult to get to. My idea is to have a netduino on the window-sill connected to a motor, which would connect to the blind string. Could I then, using a simple c# application, control the motor to open and close the blind? I would like to make this a web app, so I could control it via my android phone, and as an extension to the project, possibly have it automatically open the blind at say 7am and close it at 9pm.

 

Any advice as to the feasability, and then tutorials for controling a small motor would be appricated.

 

Thanks

[JerseyTechGuy]

Sure this is entirely feasible I'll see if I can dig out some links later and post them up here when I'm back in my office. Basically you'll need a motor controller and web server running on the Netduino. I have a similar setup for my automation setup but using a different controller.

[Paul Newton]

Hi Wayneio,

 

Welcome to the forums!

 

Your idea sounds like a really good first project.

I think you will find there is more mechanics than electronics - finding a suitable motor and attaching it to the blind may be tricky.

 

You will need to drive the motor forwards and backwards, so you are probably looking at a pair of relays or an H-bridge motor driver.

Normally I would say use an H-bridge, but I think it would be good to select your motor first so you know how much current it needs.

If its a lot, the H-bridge shields / modules that are readily available might not be able to handle the current - hence you might be better off with relays.

 

Lots of options for sensors with this project. You might use a magnet and reed switches to detect the travel of the blind, or you might use infra-red (break the beam). A sunlight sensor would be cool - drop / raise the blind automatically at sun rise / sun set.

 

Hope to see a project showcase in the future - Paul

[JerseyTechGuy]

Hey Waynio,

 

Sorry for the late response...  Let me see if I can give you a little more guidance...

 

A couple thoughts first:

 

1) If you purchase a Netduino Plus 2 it will be accessible via Ethernet.  Second is it will have an SD Card.  Using a DS1307 Real Time Clock you could build in scheduling into the Netduino and allow it to read the schedule from the SD card. This way it would be completely independent in the process of controlling your blinds.

 

2) Because your board may be on the Network (Ethernet connected) you can use an NTP server to update the clock automatically which will keep the RTC in sync.  The RTC comes into play when you lose power or Ethernet and Power as the Netduino will only keep time while on.

 

3) It's pretty easy to build a sunrise/sunset class to determine the time of sunrise and sunset.  You could also have it dynamically base the Open/Close on Sunrise/Sunset instead of an actual schedule.

 

As far as the motor controller...

 

You could use something like this one from Adafruit.  It's a motor shield. https://www.adafruit.com/products/81

 

Then maybe a motor like this stepper. https://www.adafruit.com/products/324

 

The nice thing about this stepper is that it will easily interface with the Shield and it's a stepper so you could easily control the blinds open close to open partially at Sun-Up then wait a few minutes and open all the way.  Kinda ease in the daylight.

 

Adafruit also has a number of gears and pulleys that you can look at and maybe fit to your needs.

 

This will hopefully give you some ideas and some direction.

[Wayneio]

Thanks for the replies. I've been busy with Unviersity work recently, so am just getting back to this.

 

The steps i'll take to learn this is:

 

1)Buy a Netduino and attempt to control it's onboard LED from a Win Forms Application.

2)Use the application to control a motor connected to the netduino

3)Either use a light sensor or time of day reader to control the motor, and attach it to the blind

4)Look at switching from the serial communication to ethernet

 

So, for stage 1, i'm going to buy:

Netduino Plus 2 here

USB To TTL here (although it doesnt state voltage)

 

Anything else I need to buy to get me started?

 

P.S The reason I am using a computer to talk to the netduino is that I want to also be able to override it with an application on the PC.

 

I will also follow this example to communicate with it

[Jon Henry]

If you really wanted to get creative, you could throw in a remote temp sensor somewhere in the room and implement a sort of quasi-temperature control of the room using the blind.