Automatic Window Blinds Controller (PICAXE)

Want To Build A Motorized Window Blinds Controller For About $15.00? Here is how. I enjoy having potted plants and watching them grow, but making sure they get enough light can be a challenge. I have a bookcase in front of the window in my bedroom with several plants on the top shelf. The window faces north-east and opens onto a small patio so the plants don't receive any direct sunlight. Knowing this, I choose plants that don't require a lot of light. However, they do need some so I have always tried to keep the blinds open as much as possible. My problem is that I often have unexpected things come up in the evenings and don't always get home before dark. That presents a problem. I have several digital clocks, a nixie tube clock, and a couple of other light producing projects around my home. They are not visible from outside during the day, but at night they shine like bright beacons to the world through open window blinds. I know this is a security risk and feel like having the blinds open after dark is like asking for problems.

For a long time I just waited until I got home in the afternoons to open my blinds, but my plants suffered from a lack of light. They were not dying by any means, but they were not healthy, and their growth was severely stunted. I needed to find a way to open and close my blinds automatically when I was not at home.

An automatic blind opener is not a new invention. They have been available for years. However, even the low end models cost in excess of a hundred dollars per window. Some models and styles can cost ten times that much. Most use IR remote controls. Other available activation options include timers, RS-232 interfaces, and light sensors. I needed a controller with a light sensor that would open my blinds in the mornings and close then in the evenings. However, I was not willing to pay what I thought was an unreasonable price for a simple light activated motor. Being the Maker that I am, I knew I could design and build what I needed and do it for a lot less money than what any commercial units cost.

Because I am a big fan of the versatile and inexpensive PICAXE microcontrollers, it was a given that I would design and build my window blinds controller around that chip. I decided to use the PICAXE -08M which is an 8 pin DIP with loads of features including several inputs and outputs, analog to digital converters, a pulse width modulatior, an IR transceiver option, and more features and extras than you would think would fit into its tiny package.

If you have not used PICAXE microcontrollers before I would suggest purchasing the 08M starter pack for around $12.95. It comes with the micro controller, a software CD, a serial download cable, a proto board, a battery holder, and all the basic parts you need to get started with the PICAXE system.

PICAXE 08M Starter Pack

The PICAXE system was originally designed for educational use and is. It is an excellent system for beginners and experts alike. The PICAXE software is simple to learn and use. It uses simple Basic commands that are easy to understand because they actually make sense. You even have the option of writing programs using flow charts. I usually start my projects using flow charts option and later convert them to Basic commands when I start tweaking the program. Best of all, the PICAXE software is freeware. You can download it and all of the manuals from the official PICAXE website.

Official PICAXE Web Site

I must admit that I got a little side-tracked in the beginning of this project. I decided to play around with the IR remote control options built into the PICAXE -08M. It was neat to use an old television universal remote control to open and close my blinds at will, but that did nothing to help solve my problem. I finally found my focus again and went to work designing this project.

After several weeks of electronic hardware, software, and mechanical tweaking I finally came up this design. It is simple, easy to build, does a great job, and is just plain cool. If you have any spare or salvaged parts lying around you can build the whole thing for a lot less than $15.00. If you have to buy everything you can still build this project for around $20.00 including the batteries.

I really enjoyed designing, building, and tweaking this project and I learned a lot in the process. Now my plants get the light they need, my other projects are not shining through the open window blinds at night, and I feel better knowing the blinds will close at night whether I am there or not.

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Be sure to check out the "Take it Further" ideas in step 12.
They are sure to spark your imagination and make you
want to fire up that old soldering iron and get busy
on a truly fun and practical project.
***************************************************************

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Step 1 The Parts You Will Need

- PICAXE -08M Micro Controller, Advanced Micro Circuits $3.10

- ULN2003A Darlington Array, BG Micro #ICSULN2003 $.59

- DPDT 5.0V Relay, BG Micro # REL1090 $1.19

- Solarbotics GM3 Gear Motor, 224:1 6V, Maker Shed Store $5.50

- 3.5mm Stereo Jack, BG Micro #AUDCA017 $.36

- 4 X 1.5V AA Battery Holder, BG Micro #BAT1068 $.79

- Battery Snap (9V style), BG Micro #BAT1033 $.25

- LM7805T 5.0V, 1A, Regulator, BG Micro #REG7805T $.40

- Small Project Box, BG Micro #ACS1157 $1.95

- Small Proto Board (2 3/8), BG Micro #ACS1433 $.89

- 8 Pin Dip Socket, BG Micro #SOC1036 $.10

- (2) 16 Pin Dip Sockets, BG Micro #SOC1038 $.08

- Light Dependent Resistor, Radio Shack #276-1657 (5 pk) $2.99

- (2) SPST Switches, BG Micro #SWT1043 $.20 for both

TOTAL $15.90

You will also need the following items:

- Resistors: 1 each of 10K, 22K, and 100K (>= 1/4 Watt)

- Wire, solder, small bolts and nuts, Velcro strips

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RECOMMENDED SUPPLIERS:

BG Micro
BG Micro Web Site
I am only a hobbyist and I don't spend a lot of money on projects, but the people at BG Micro have always treated me like I was their most important corporate customer. That kind of service is nearly impossible to find these days. Add that to their great parts selection and low prices and you have a winning combination.

Maker Shed Store
Maker Shed Web Site
I love checking out their stuff at Maker Faire

Advanced Micro Circuits
Advanced Micro Circuits Web Site
These people are sometimes a bit slow when it comes to shipping, but it is worth the wait because they have the best PICAXE prices in the US.

Your own stash of surplus and salvage parts.

"To invent you need a good imagination and a pile of junk"
Thomas A. Edison

There is also a schematic below for easier viewing. Right click on the schematic and choose "save as" to save a copy to your computer.

Comments

[reverbflange]

Awesome tutorial! I'm gathering supplies to make one myself! I just ordered that PICAXE 08M starter kit, but am curious.... does it come with the IR transceiver right out of the box, or do I need to order it separate? I like the light activation, but that isn't really suitable for my circumstances. The remote controlled idea sounds awesome though! If I can get one to work correctly, I'm going to build one for every room in my home :)

[biochemtronics]

The PICAXE does not come with a IR emitter or receiver. You will need to order a receiver separately. As for using the remote control, a word of warning. You may run into problems getting the remote to work if you are dealing with direct sunlight coming in your windows. It has to do with the IR in sunlight overpowering the weak IR coming from your remote. I had a toy helicopter that used an IR remote. It was pretty useless outside or in front of a window with direct sunlight coming into it. Best of luck with your build.

[mart_1986]

hi there

im a newbie to electronics im really intrested in this idea.how would i put it on a timer as i need it to open at 10am and close at 6pm every day for 12weeks each year (its for my racing pigeons)

[biochemtronics]

 For a timed application I would just use a power supply and a household timer. The full open and close positions could be controlled with simple limit switches.

[kent01]

I would also like to do a timed application. What if I adapted your design using the 08M2, removing the light sensor, and adapting the code to use the time variable to count the seconds between opening and closing? That would at least be a start, but I wonder if it would work, or whether the time function would use too much battery power.

You mention using a household timer, but I have never done any circuitry before so I'm not sure where to start with that. Using the 08M2 would allow me to follow your design fairly closely.

BTW, I want timed blinds to help keep the house cool in the summer and to help wake me up in the morning.

Any tips would be greatly appreciated! If I figure something out I'll post the solution here.

[ravonricks]

Well Put together project!! Do u have a larger schematics?

[niftyswell]

To open and close you need two solar power sources. The first one would be a standard source that has a cut off actuated by the blind itself when if fully opens- a fan pull toggle switch would work just fine. The close would require you to get a simple 3 dollar solar light from a department store that has the battery that charges during the day. Again, the close action would actuate the power to stop flowing. You have to ensure the open and close triggers are consistent enough not to trigger both at the same time which should be simple enough to achieve by simply using the blinds themselves to interfere with the electronic eyes. Then the only issue you would have is the battery running out of juice keeping you from actuating a close sequence...but it would use such a low amount of juice the battery should last for quite some time.

[mongorsf]

Anyone familiar with solar cells, I wanted to do this project but using solar cells to start the motor to open the blind and keep tension on a spring loaded pully all day while the panels had light and gave charge to the motor. Then the motor would release the tension once the sun went down and it lost its voltage, allowing the spring to release.

The motor he listed above is 3v, that would only take 6 3x6 panels at $.60 each (typically), removing the need to change batteries and would only open on days that were sunny enough to deserve the blinds to open. 6 panels would give only 12 watts of power, but if geared right should be enough to slowly open them.

The only thing I worried about is that it might burn out the motor keeping a charge on it all day, everyday, no?

[biochemtronics]

Keeping current on the motor all day would not be a good thing. It would damage the motor for sure. However, you could replace the batteries with a bank of solar cells and add a slight delay so that they get full sun and build to full voltage before powering up and starting the motor. You would also need to start closing the blinds before the sun goes down in the evening so the solar cells would have enough power to operate the motor. Another option would be to use a couple of super capacitors in the circuit with the solar cells instead of batteries. If you use 3 or 4 of they should hold enough power to open and close the blinds. Also, don't leave out the voltage regulator. It only takes a few extra millivolts to kill the picaxe.

[mongorsf]

First, thank you for your reply.

I think you might have misunderstood my goal.

You are talking about delays, capacitors, circuits, etc.

But I am looking to have NO circuits, batteries, or light sensors to determine when they open or close. (I don't think I would even need the voltage regulator because the cells are not capable of generating more then 3.2v in the brightness sun.) I was thinking that I might use a DC to DC boost converter to keep the voltage at 3v as long as possible.

Due to a spring on a pulley line, the natural state of the blind would be 'closed'. When the sun hits the panel, it puts voltage to a motor, pulling the line, stretching the spring, and holding the blind open. If it gets cloudy or sun goes down, there would not be enough voltage going to the motor and it would lose power and the spring would take over and pull the blind back to natural state of 'closed'. So as long as the solar panel outputs voltage, the motor has power to fight the spring.

The motor would be geared and open VERY VERY slowly with the small amount of power the solar is giving it, so the motor would really not have that much constant power going to it. I am guessing 3v with 12w at the sunniest part of the day.

Is there any type of motor that can handle the constant voltage or maybe some other idea similar to this.

Thanks,

Gary

$10 a motor
3v -3 rotations per min- (very slow eh)
http://www.ebay.com/itm/3V-3RPM-Torque-Gear-Box-Motor-New-/260793928051?pt=AU_B_I_Electrical_Test_Equipment&hash=item3cb8878973

or 3v 10RPM
http://www.ebay.com/itm/3V-10RPM-Torque-Gear-Box-Motor-New-/220765783849?pt=LH_DefaultDomain_0&hash=item3366aa8729#ht_4685wt_952

Boost converter (but I need to find one that will do 1.5v to 3v)
http://www.ebay.com/itm/300601910406?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649#ht_3634wt_952

[biochemtronics]

Gary:

I did understand your goal.In theory the method you are talking about using would not need anything more than a bank of solar cells, a spring and a motor. However, I do not think there is any way to do it this may for a couple of reasons.

First you cannot allow current to continue flowing through a motor when it is stalled because its inductive resistance drops dramatically when its stops turning. The motor windings will then act like a short circuit and the current flowing through them will increase and cause them to heat up and fail. There is no way around this. If you limit the current so this doesn't happen then there won't be enough to start the motor. All motors use several times as much current to start as they do to run. Also, all motors pull more current when the armature stalls. If the solar cells you are using can supply enough power to start the motor they will supply enough current to damage the motor if it stalls.

As for using a spring to return the device to the original starting position once the motor looses power, it sound good in theory but I don't think it is likely to work for this reason. When the motor is opening the blinds it is also going to have to wind up and hold the spring as well. This is going to dramatically increase the needed electrical current and the motor size needed to overcome the friction of opening the blinds and the current needed to overcome the spring pressure. That is going to require more solar cells to increase the current and the additional current will only serve to fry the motor faster once it stalls.

Also, you mentioned using a very slow gear motor. That will work great when it comes to opening the blinds but it is going to present a serious problem when it comes to letting the spring close them. The best way to understand this is to take a small gear motor and try to turn it using pliers on the output shaft. This is what you are thinking about trying using a spring on the output shaft. With a 1 to 3 rpm gear motor you are going to damage the gear motor before you get it to turn using the output shaft. I cannot even turn the gear motor I used in this project using the output shaft without using excessive force.

I hate to be such a skeptic and I do not want to discourage you but I don't think this is going to work. Perhaps there is some other way. A slip clutch on the gear motor output shaft may prevent the motor from stalling once the blinds are open. The motor could keep turning and keep tension on the shaft until the sun goes down and you loose power. However, even with that you are going to have to get the spring to turn the output shaft in reverse to close the blinds. Again, the extra power needed to wind up the spring to this incredible torque (for such a small motor) is going to be a limiting factor.

You have some really great ideas and I am sure there is some way to do this simply. I just don't know how. I suggest you get some motors, solar cells and springs and give it a shot. Even it it doesn't work you will gain some knowledge. Best of luck and please do keep my informed.

[mongorsf]

You have given me food for thought and some direction to my challenge.

I think with a small guide on my line that would flip a manual switch at a certain point and have it shut the motor off at least I can have the blinds all nicely opened and the sun shining in when I wake up. Then just use some sort of quick disconnect that I can release the line manually at night.

If what your saying is that once the slow gear motor is off, it wont turn back on its own, then I just have to make the spool that collects the line, be able to 'pop' off the shaft and unravel the line, then 'pop' it back on once the blind is down, resetting it for tomorrow.

halfway is better than none :) (for now)

Thanks again

[arbayer]

Sorry I am fairly new to all this... But would it be possible to set it up to a clock of some sort rather than the light dependent resistor? for example set it so they open every morning at 8:00 a.m.? If you have an idea of how that would work please let me know. Thanks!

[hydroxyethyl]

I used these plans to build a chicken coop door opener like Vasileiosh did. However, I used the GM3 motor to lift the door. A few changes to the plans I made were: 1) I tied pin number 3 to ground with a 100K ohm resistor. (I believe living the inputs floating can lead to battery drain). 2) I also added the following lines before the readadc command disablebod sleep 26 enablebod Essentially this puts the microcontroller into low power sleep mode for ~ 1 minute. 3) I used a bobbin (the reel in the bottom of a sewing machine) to wind/unwind string to the door. I tried a larger reel but the motor did not have enough torque. 4) I shielded the lifting mechanism and string with hardware cloth. My chickens are very curious and tend to stand on or peck at something new. I hope this helps out anyone else trying to use these plans to make an auto opener for their chicken coop.

[brbd]

Hello There,
This is really awesome.
Could you please give me the plan and instructions how to build this, I wanted one for my coop, your help is really appreciated.

Thanks
[e-mail]

[batman96]

I was thinking about one that would work with my alarm clock, also it won't use any microchips. It would have a latching diode or relay in line with the alarm beeper, when it beeps it would roll up the blinds using a geared down motor from a tape deck, when it gets to the top it would push a normally closed button to shut off the latching diode or relay.
Any other ideas or suggestions would be appreciated!
thanks

[Jakeg]

Hey there, I would love if you could get in touch with your friend to get more info on those motorized shades. I want to do thin in my house but i don't want to spend over $100 for the store bought version. Please help. -Jake

[biochemtronics]

He said that he used a pully that came with the shades. It was made to mount at the bottom of the window to keep the string tight. He says it is a beaded string, not a regular string. For regular string any sort of spool or pully that would mount easily to the motor shaft would work. Perhaps you could check the solarbotics web site and find something there that may work like a wheel made to fit the motor shaft. You could always glue or screw a wooden spool to the wheel and wrap the string around it. Best of luck.

[bneese]

I am going to attempt to do this on 2 blinds we have in our vaulted great room. I do however need some advice. To open and close my blinds you pull on 1 of 2 strings. How could I accomplish this?

[biochemtronics]

A friend made one of these for some window shades. They had 2 strings that operated the shades. He mounted a pulley (similar to a small thread spool) on the motor, tied the shade strings together, and wrapped them several times around the pulley. When the motor turned in either direction it would pull on one string while unwinding the other. It worked great for him. Hope this helps.

[kd5crs]

Well, I had a whole big comment detailing my experience, but the website ate it. To summarize: 1. It works great. 2. I used the IR sensor for control. 3. I used a reed switch to say when the blinds are open, removing the need for the buttons or fiddling with timing. 4. The motor controls the shaft inside directly, rather than through the worm gear on the hand-turn rod. That improves battery life, speed, and reduces load on the motor to almost nothing. 5. Everything fits inside the box at the top of the blinds except the batteries, which I am keeping accessible until I know how long they last. I'm using 2" blinds. 6. Thanks for the awesome project, and 7. Time to automate the other blinds in the house!

[bneese]

kd5crs. This is what I would like to do. Do you have any documentation on how to go this route? My blinds use 2 strings to open and close, so I would like to be able to do it directly from the shaft. Plus these blinds are going to be in the vaulted great room so I would like to use a remote. I have never done anything like this before so please forgive me if I am a newbie. Any help you can give me would be great! thanks.

[biochemtronics]

I like your modifications. I plan to incorporate them into my next blind control. Thanks for sharing this with us.

[kd5crs]

Thanks. My first one has been in use for a month now, and I've made some upgrades. I have three total in operation. 1. I replaced the reed switch with a contact switch. Simpler, more reliable, and keeps everything contained in the top of the blind. One input for closed, one input for open, and a piece of metal taped to the blinds that is connected to 5V. When it closes the circuit, the input goes high, and the blinds stop moving. 2. Battery life is not great. It's made worse by the fact that they start behaving unpredictably when the voltage gets low. Did you ever add a low voltage indicator? I'd like to add that to mine, but I'm not sure how.

[kd5crs]

An update on battery life: I got 21 days of daily use from 4 AA alkaline batteries. How does that compare to everyone else?

[heyitsmebenjamin]

I'm trying out your awesome window blind system. However, I am having trouble downloading the schematics -- I can't download them... i get a "tmp" file. Any help?

[thelma.kastl]

My students are having a difficult time with the schematics.  We need to complete this project asap.  I have tried sending a private message.  Is there any possible way you can contact us? Thanks Ms. K at [e-mail]

[mathchris]

 I can't download the schematic. It gives me a .tmp file instead of the Eagle file.

[bennygorilla]

Could you go into a bit more depth with this setup for the shades please:
 
Did you use the IR Detector in place of the LDR?

Does it have to be a universal remote that is needed for the codes or could i use a different one?

Where and how would you you use the 2 pots?

Many tahnks for taking the time to answer my Q's

Ben

[biochemtronics]

 Yes - I used an IR detector instead of the LDR

You will have to use a SONY TV remote control, or as in my case, a universal remote control setup for a SONY TV since the PICAXE only reads SONY TV IR codes.

The Pots - Since the guy I worked with on this project lived 800 miles away from me and know nothing about PICAXEs, I used the pots to set two variables on the PICAXE inputs. The PICAXE code then read those variables and used them to time the motor that opened and closed the blinds. It worked great. Increase or decrease the resistance on the pot, increase or decrease the time the gear motor turns to open and close the shades. This worked much better than the method of programming the PICAXE by trial and error to get the timing just right like I did on the original blinds unit I made.

[bennygorilla]

and where were the pots located in the circuit?

Sorry, i'm not the best at circuits quite yet.

[purpulhaze]

I'm interested in doing a project like this but with an avr microcontroller instead. Can you give me a lil more detail as to how you got the timing of the motor to work?

[biochemtronics]

 I have never used a AVR so I cannot help you with that. To get the timing correct I installed the unit on my blinds and kept changing the time settings until it opened and closed the way I wanted it to. Others have used limit switches to control the full open and full close positions. This works much better but requires mechanically attaching the switches to the blinds.

[purpulhaze]

I've been checking out that Solarbotics GM3 Gear Motor but can't figure what it really is. Is it a servo or stepper motor? Maybe more like both? Since I live in an apartment I need to design it so that it can fit outside of the blinds without modification. So it would have to control the hand rod. I don't think I can use a servo since I believe I need maybe a few revolutions to open or close. I'm thinking of using a stepper or maybe that Solarbotics GM3 Gear Motor.

My plan is to get a working wired prototype. Then I would like to make it wireless and be able to be controlled via my pc or remotely through the web. 

Connecting directly to a microcontroller seems straight forward but when I start thinking about going wireless it seems a lil' more complex and maybe a bit pricey too.

What are your thoughts on this?

[biochemtronics]

 Purpulhaze: The G# is neither a stepper or a servo. It is simply a gear motor. Using my design won't require any modification of the blind. As far as controlling the unit with no wires would be simple. Doing it remotely is a little more involved than i can handle. 

[purpulhaze]

kd5crs posted " The motor controls the shaft inside directly,rather than through the worm gear on the hand-turn rod." Didn'tthink this could be done without at least some modification to theblinds.

I think I figured out how I'm gonna to do it all. Got a lil' confusedtrying to figure out how to get one microcontroller to do everything.So  I'm not going to go that route. One microcontroller for theblinds module that would be connect  to a 2 channel rf wirelessmodule I purchased off of ebay.  Then I'll wire the remote to myarduino. As long as my computer is on I can telnet or remote desktop tocontrol the blinds. 

Love your instructable. Thanks for sharing. It's perfect for some of myhome automation projects.

[greeneye82]

This is my first picaxe project and I am new to the programming stuff. I've got my circuit working fairly well, however I am perplexed about the code. My motor will open and close the blinds when i shine a flashlight or cover the photocell. I just can't get it to stop when i reach a certain light level. In reading the code I can't see anywhere where it would tell the motor to stop turning. It's like when it tells it to open, it just keeps spinning and doesn't know when to stop. Same thing when commanded to close. Is there a addition to command the picaxe to stop? or do you think i have a wiring issue? also, is it normal for the relay to continuously make a clicking noise when the blinds are openning? and not closing?

[biochemtronics]

Congrats on taking on a picaxe project. I am sorry you are having difficulties and will try to offer some help. As for the gear motor not stopping when activated and the relay constantly clicking - it sounds like a motor noise problem to me. Your wiring could be the problem or even the circuit layout but you won't need to change either. Just get a few disk caps (I used 0.1 caps but the value is not that important and any you have laying around should work). Solder one between the two motor terminals and then solder one between each motor terminal and the metal motor case. The motor case is pretty easy to solder to if you hit it with a piece of sandpaper first. This should eliminate all of the problems you are having. If it does not, then go back and double check the code around the pause commands. best of luck. The gear motor is suppose to cut off after a specified time using the 2 pause commands. On my controller one pause is for 6150 and the other for 6600 (as seen in the code I posted). Yours will have to be changed for your gear motor and blinds.

[greeneye82]

Thanks for your suggestion. I added the caps like you said, and I didn't get much of a change to the operation. I'm still tinkering with it though. I've adjusted the code to your specifications. I'm using all the same parts as you outlined for this project too. If you get a moment, check out my video of the issue that I am having and maybe something will jump out at you. I'd appreciate any info. This has been fun so far. http://www.youtube.com/watch?v=oSLJAJR4iTs

[biochemtronics]

I checked out the video. I wish I could help more, but I am really at a loss as to what it going wrong with your circuit. As I am sure you have realized, the motor is not suppose to step like your's is doing. My guess would be an error in the code but that is the least likely cause. Several other people have built this circuit with no problems so the only advice I can offer is to tear it down and start over from scratch. Believe me when I say that it is very easy to get a wire or pin number crossed up. Especially when the picaxe port numbers are not the same as the pin numbers. i seem to get it screwed up at least once on every picaxe project I build. I wish you the best.