Home Automation through Cellphone Keying (H.A.C.K)
I always wanted to control my lights and other appliances in my room remotely while I’m somewhere else. Many a times I forget to switch off the fan or AC in my room and then I have to go back and switch it off. I always wondered how cool it would be if I could control my appliances through something like my cellphone (which I never forget to take). Well now I can see that dream right in front of me. Yes, its yet another hobby project by Kaushani and me. Its the ‘Home Automation through Cellphone Keying(H.A.C.K)’ .
Fig.1 H.A.C.K’s Main Circuit
For those who are not aware of, for every key press on a standard telephone keypad an audible ‘beep’ is generated. It actually is a signal which is a combination of two distinct frequencies i.e. every key is uniquely defined by the combination of two distinct frequencies. Many (multiple) frequencies are used in which combination of any two defines a key on your keypad hence the name ‘Dual Tone Multiple Frequencies (DTMF)’‘
Fig.2 DTMF Frequency Combinations
H.A.C.K uses a Full DTMF receiver CM8870 from CMD which gives the binary output of the key being pressed. For more details refer the datasheet.
Fig 3 DTMF Receiver Circuit
The DTMF receiver circuit is interfaced with an ATmega16 MCU which is used to drive the external appliances ON or OFF. For demonstration purpose I’ve used 3 leds to be my external appliances. I’ve also used my old NOKIA 2300 in the automatic answer mode and the earphone is used to give input to the DTMF receiver circuit.
Working:
- Call the control phone from any other phone from anywhere in the world.
- The control phone being in the automatic answering mode picks up your call.
- Press the correct password to have access.
- If the password is correct a buzzer will ring which you can hear through your phone otherwise you can’t control the appliances.
- Press Keys on your phone to control your appliances.
- I’ve used the keys 1 to 7 to control the LEDS but the other keys 8,*,0,# can also be included.
- I’ve not used any password in the demonstration.
Feel free to post your queries and feedback in the comment section below.
GALLERY
keep up the good work. Only innovative people like you can really make a difference and reach further in life.
@Parth
Thanx dude. I really appreciate that.
hi
wanna ask u something. how did u connect cellphone with DTMF receiver??? if i m using k800i how i m going to do??? pls guide me… thanks
@Ah-Bao You can use the handsfree earphone for K800i then remove the casing to see speaker connections. There will be only two wires. The one which is connected to the body of the speaker is the ground and the other positive wire. You can use these wires to give input to your DTMF decoder.
can u pls show me in details how u connect cellphone headset with DTMF reciever..
thanks in advance
@Ah-Bao Thanks for commenting. Anyways, when you open up the casing of the speaker or if you cut the earphone wires (please take care that you cut after the mic section only) you’ll get two wires like this http://bit.ly/cRFok1 . Connect these wires to Pin1(V+) and pin2(V-) of the DTMF decoder. If you still have problem do let me know.
hi.
wanna ask u something i got problem with DTMF receiver. pls help me to check. after cut off k800i headset wire i can see there r brown n green two small wires n i join them to normal connecting wires n brown go to capacitor C1 which is 0.1uF series with R330k n go to pin2 (IN-)and green go to pin9 (VSS). does my connection correct??? pls help me… the problem is i don’t have oscilloscope. i m part time student that’s why i didn’t have it…
so if u have some idea how u connect cellphone headset to DTMF receiver. can u pls show me details on it… thanks in advance
thanks n regard
i send my circuit diagram pls help me to check.. ur mail address is that one right dydflyer@gmail.com thanks…
hi would you please help me because i have being trying the same thing but cant go thru. i am doing a project which i will be using my cell phone to switch on lights in my room with the first call to the reciever phone,then with the next call to the reciever,the door will open without interfering with the lighting bt the door wii close after lets say one minute.please i need help on this on the working of my circuit diagram.thanx in advance
@Kevin wouldn’t it be better if you make a call and have the options for either controlling the lights or the door as per your requirement. For that you can check the first key pressed after the call for e.g. ’1′ to control lights and ’2′ for the door. Still if you really want to make different calls for the different controls, it can easily be done in your code.
hi,
i want to use any other device rather than cell phone then have you any option like Sim card interfacing circuit?
@hir For that case its better to use a GSM module instead of the DTMF decoder + cell phone which can be serially interfaced (UART) with the MCU and do even cool stuffs like controlling through SMS!
would you mind helping me out with the circuit coz am kind off worked out,i cant come up with one
does it require a programming in the remote cellphone unit?..do i need to install any application to dtmf during a call..
*i mean to send a DTMF a signal during a call