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how to make this device? Answered

hi, i want to make a device, please tell me how... there is something that looks like a tv remote . it has 9 buttons on it. And there are 9 light bulbs. when i press each button, each of the 9 light bulbs should light up. for example, when i press button 1, light bulb 1 should light up. when i press button 2 , bulb 2 should light up, button 3 turns on bulb 3, and so on. this needs to be wireless. i have done some research and i have found that i need something called an RF transmitter and RF receiver. I just need some hints on how to make this device. i hope it is clear what i want , english is not my first language, if its not clear let me know and i will clarify.



10 years ago

I've done some work interfacing RF modules with AVRs. The modules were made by liapac, but there are many nearly identical devices. I can give you the project link, if you like.

But it's not something you can just throw together--if you don't have any experience programming microcontrollers. You'll need to learn something about serial data transmission, as that's the norm with most cheap RF modules. They are "noisy" devices, too, so some sort of encoding is required (I used manchester encoding.)

Plus you'd need something to handle current--a relay or SCR for each light attached to the receiver(s)....

hello. thanks, i have no idea what all the things you said mean, because i am not an engineer, but i am willing to learn! please tell me the project link. also i am going to start googling "programming microcontrollers" and "serial data transmission" and "manchester encoding" .

Sure, here's the link-- the schematics and AVR source code is on the site, too. The receiver is actually the small board on top of the other device (a hacked C64DTV.) The transmitter is obvious.

And here are the RF modules at sparkfun (actually slightly different, but functionally the same.) They also have much more sophisticated Nordic modules but you'd pay 3 or 4 times as much (you need two.) And your application doesn't call for high-speed.

The RF modules can be used something like a one-way serial cable. But they differ from a cable; signal noise is fairly high--most often when the transmitter is silent for quite some time, or when long "empty" bit fields are transmitted. For instance, sending a zero, which is a bit field like: 00000000. That's potentially problematic.

Manchester encoding is a schema where never more than two sequential empty bits are transfered, regardless of the number. There's a catch--it takes twice as long to send information, as each 8 bit number takes two bytes to transfer.

One second thought, you probably wouldn't even need to encode--you could just send a number several times, it would probably be correct 90-95% of the time. Just compare and reject any values that don't fit. If you receive four #10's and one # 6, you can be sure that it's a 10.

Of course, the microprocessor thing is separate. It can be fairly complex, but you have several "simple" options, too--basicstamps, Arduinos, PICaxe, etc. I used AVRs (because I like C, and avrgcc is free), but PICs are good, too.

Don't try to use the email link on the site, the href string is wrong -- I never bothered to fix it :-( But you can PM me here...


10 years ago

You could use infrared remote control (like TV remote) instead of RF, if the receiver and lights are within appropriate range and line-of-sight from the remote. In fact, it would be fairly easy to USE a TV remote as the remote control...

actually i will not be aiming the remote at the light bulbs, the lightbulbs are in a different room

You could research model airplane remote control transmitters and servos. With one transmitter they can actuate or control several functions on the remote airplane. Or you can look into remote controls that turn on the lights or power of a ceiling fan, maybe even remotes sold to light up a christmas tree. These are single-channel or one device only controls, you may need to have 9 of these or need to find a multi-channel or device controller. Is this project to control low-power LED lights or do you need something with full-size lights. Many others will be able to help.