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Send 10V to home thermostat via internet


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Hi everyone, I have a Honeywell thermostat ($40) that can handle some simple remote control access (see pic attached).

 post-35565-0-49931600-1389155929_thumb.png

 

I have also picked up a MSP430 for $5. Looking to control this from my phone.

I have zero experience with anything like this, Hoping to get help here on the forum!

 

bluehash let me know I'll need a relay board, makes sense, found this on dealextreme for <3$ w/ free shipping....

 

http://dx.com/p/arduino-5v-relay-module-blue-black-121354

 

Any reason it wouldn't work?

 

Will I need some kind of power supply?

 

Also, whats the cheapest way to go about getting the Launchpad on my home network? (I'm assuming the Launchpad will have an ip address that I can type into a web browser, and some kind of GUI or something on the Launchpad to allow access to the relay?)

RF?

Wfi?

Bluetooth?

My router is close to my thermostat, so Ethernet is an option, but nobody likes wires...

 

Thanks in advance for any input!

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You might get away with using transistors instead of relays, depending on the exact behaviour of the thermostat

+--------+  +--------------------------------------+
| TL8100 |  |        home automation system        |
|        |  |                                      |
|        |  | +12                                  |
|        |  |  |                                   |
|        |  |  +----[100k]--+                      |
|        |  |  |            |                      |
|        |  |  E\           |                      |
|        |  |    \|B        |                      |
|        |  |  PNP|--[10k]--+                      |
|        |  |    /|         C\                     |
|        |  |  C/             \|B                  |
|        |  |  |            NPN|--[1k]-- to MSP430 |
|   X O--------+              /|                   |
|        |  |               E/                     |
|   C O--------+            |                      |
|        |  |  |            |                      |
+--------+  | ===          ===                     |
            |                                      |
            +--------------------------------------+

The circuit from Deal Extreme will not work as is:

- the relay accepts voltages from 5 and up

- the microcontroller cannot source enough current to actuate the relay (ie: the microcontroller will fry)

- relays have high inductance, shutting them off without a freerun diode will force a current from your microcontroller, thus frying it

 

You'll need a power supply to power the 12VDC and the microcontroller (1.8 - 3.6 V in case of an MSP430)

For connectivity you will either need some kind of home control bridge which allows you to use a small RF module, or you need to buy a WiFi or Ethernet booster pack to allow it to be accessed over TCP/IP or UDP/IP.

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Sometimes adding networking is unreasonably expensive - couple of thoughts

on alternatives that could consider from cost angle (don't use the MSP430).

 

Depending on what router you have it might be possible to use it to control the thermostat.

(e.g. if it can run alternative firmware, like open WRT, or similar, and if it has one or more I/O pins available).

May require more software sophistication than using the MSP430, and may not want to mess with your router

(or could use a secondary router for this, larger than the launchpad, but can often be found inexpensively second hand).

 

Another option might be the EKLM3S8962, if they still have any on this deal at $20 http://forum.stellarisiti.com/topic/694-stellaris-ekt-lm3s8962-kits/

it includes a wired ethernet port, microcontroller, even has a display.  Again, not an MSP430, larger than the MSP430, programming it uses different

tools, but similar in effort.  (Unless you want to use something like eLua, which might be easier than C.)

 

Either of these solutions would still need hardware to control the 12 v line.

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Hi @@K2csq7,

 

Cool project!

 

For the networking aspect, I would look at the CC3000 Boosterpack that @@spirilis mentioned, and use an MSP-EXP430F5529LP launchpad (more memory to handle the Wi-Fi).

 

There is actually a blog post someone did a few months ago that used a F5529 launchpad + CC3000 to let you lock/unlock your door from your phone, written in Energia: http://e2e.ti.com/blogs_/b/msp430blog/archive/2013/11/13/how-to-build-a-wi-fi-door-lock.aspx You could probably re-use a lot of it for getting the Wi-Fi up and working for this project. Someone did a WiFi Lamp too, that actually might even be closer to what you are doing because it was basically controlling a relay: http://e2e.ti.com/blogs_/b/msp430blog/archive/2013/09/22/how-to-build-a-wi-fi-lamp.aspx

 

Regards,

Katie

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Thanks everyone for the replys, I have a cc3000 in the mail!

 

The circuit from Deal Extreme will not work as is:

- the relay accepts voltages from 5 and up

- the microcontroller cannot source enough current to actuate the relay (ie: the microcontroller will fry)

- relays have high inductance, shutting them off without a freerun diode will force a current from your microcontroller, thus frying it

 

So because of #3, I can't use a relay board?

 

 

 

 

spirillis, Do you have a link for a suitable NPN type transistor? I hope the 2553 can hack it... I put my email in for notification when the 5229 is back in stock. 

 

Probably use a transistor for this, NPN type, and the CC3000 WiFi boosterpack. Note that the G2553 chip coming with the cheaper launchpad is a bit short on memory to use the CC3000 for anything beyond simple stuff, but this might be simple enough for it.
 

 

on alternatives that could consider from cost angle (don't use the MSP430).

Thanks, I do have an old netgear router or 2 laying around, but I'm going to try and make it happen.

 

 


 

Hi @@K2csq7,

 

Cool project!

 

For the networking aspect, I would look at the CC3000 Boosterpack that @@spirilis mentioned, and use an MSP-EXP430F5529LP launchpad (more memory to handle the Wi-Fi).

 

There is actually a blog post someone did a few months ago that used a F5529 launchpad + CC3000 to let you lock/unlock your door from your phone, written in Energia: http://e2e.ti.com/blogs_/b/msp430blog/archive/2013/11/13/how-to-build-a-wi-fi-door-lock.aspx You could probably re-use a lot of it for getting the Wi-Fi up and working for this project. Someone did a WiFi Lamp too, that actually might even be closer to what you are doing because it was basically controlling a relay: http://e2e.ti.com/blogs_/b/msp430blog/archive/2013/09/22/how-to-build-a-wi-fi-lamp.aspx

 

Regards,

Katie

The lamp one is spot on, but the triac boards seem to be all taken.... can I get all the items on the BOM for the 2ch triac board and use something like this?

http://www.ebay.com/itm/like/400590201590?lpid=82

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