Hi everyone,
I am trying to build a system to connect to my intercom at home, it would call my cellphone when someone calls the intercom and I want it to respond to a keypress on my phone and open the door.
At the moment I have a GSM module similar to THIS ONE.
I can call my cellphone from it and have a conversation. What I want it to do at this point is to be able to recognise a button press from my cellphone. Let's say I pick up the phone, press 0 on my keypad and the arduino should recognise that command and turn on an LED.
Anyone has any idea on how to accomplish this? Would the GSM module have some kind of functionality built in for this?
I think that you are looking at the wrong end.
If you want something to happen when you push a button on your phone, you need to have software on that do make it happen.
You phone has software to handle phone calls.
It likely has software to handle text messages.
It might be a smart phone where apps can be written, perhaps one that can communicate that a button has been pressed.
I think you might have probably misunderstood what I am trying to achieve.
Let's say you call some service and the robot says "Press 1 to talk to someone", you press "1" on your phone and the other end understand that you pressed "1".
That is what i am trying to achieve with the Arduino, detect that the "1" was pressed.
Ah, cool!
So your device will place the call and then listen for the tone that is generated when you press a number.
Sounds great.
I do not know what the GSM has to determine the frequencies coming in on the phone audio.
Edit: DTMF is the way to describe phone number tones. Does your GSM support DTMF detection during an active call?
I found one GSM sketch that apparently does.
DTMF_value = gsm.GetDTMFSignal();
Where DTMF_value is used for a remembering of the last received DTMF value.
Nice,
I found the answer myself just now and wanted to add the info here
Indeed - DTMF is the functionality I am looking for and, although my GA6 Module does not support that, it seems that a lot of SIM900/SIM800 chips do, so I just found a SIM800C Arduino shield and waiting for it to be delivered tomorrow
I'd like to do the same thing to help someone who has a disability respond to callers at the door and I would be interested to see how you interfaced the intercom to the GSM module. Did you have any problems with audio levels and acoustic feedback?
