Introduction. DTMF (Dual Tone Multi-Frequency) signaling is used for telecommunication signaling over telephone line in the voice frequency band between. Overview. The MT module is a low power device DTMF decoder chip. It is a complete DTMF receiver integrating both the band-split filter and digital. Pin configuration of MT DTMF decoder DTMF Decoder Circuit Unit design Figure 6 is the DTMF decoder unit. The circuit is used to decode the mobile.

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If you like this page, please do me a favour and show your appreciation: I understand most of the circuit. Hi First of all, nice tutorial and good job! I understand the bottom half completely. After a lot of googling, an obscure forum post in an indian forum stated that the k resistor between tip and pin 2 works for old Nokias, but is too decodef for modern phones. I can also be found on Pinterest and Instagram.

Is it too late to modify my answer? Logic 0 release from button ‘2’ TOE: Scott C 19 June at Mark Verheyen 29 October at I understand that the 0. I don’t think I can afford one of those. This has been done many times by many people, but typically it is done with an old Nokia phone.

It is a very useful bench test equipment for testing and finding out the frequency of various devices with unknown frequency such as oscillators, radio receivers, transmitters, function generators, crystals, etc. The DTMF signal is received through the 3.

MT8870 DTMF Audio Decoder Module

After a few seconds of playing with the buttons, the whole thing suddenly stopped responding. If, while it is working, I keep pressing buttons on the phone constantly, it will not lock up.


On the telephone exchange side, it has a decoder circuit to decode the tone to digital code. Click the image above to enlarge it. Hello Scott, Could you please tell me how to deal with it in order if I want to use microphone, like connect microphone to 3. VegaObscura on April 30, These are special tone which are normally not found on our telephone. I provide a link to the module in the “Parts Required” list above Without a tm8870 or other way to get data, you have to form theories and test them open loop.

Arduino Prototype uses all standard through-hole components for easy construction, two of which are hidden underneath IC socket. I didn’t want to go quite as low as 4. You will need the following parts for this project.

Seems like I can just connect microphone and work with it If you wanted to use a microphone, you will need to boost or amplify the signal before sending it to the DTMF module. The phone I am using is a Samsung Galaxy S4. I will try getting a headphone jack splitter and plugging in a set of headphones with the phone and circuit board, so I can listen and make sure the phone is putting out the audio signal. All my knowledge about these modules is contained within this tutorial. This still did nothing.

But if I stop pressing anything for even five seconds, it locks up every time.

So if this tutorial does not help you, then it drmf unlikely that I will be of any use. I must warn you, however that this is a line input and NOT a microphone input.


Logic 0 Detection of dial tones is reflected on the bit TOE, while the output Q4, Q3, Q2, Q1 indicate the dial tone that is being detected on the telephony system. On the other hand, the onboard LEDs D1 to Ddecoder will light up depending on the tone received, and will remain lit until the module receives another tone.

MT DTMF Decoder | Sensors & Modules

But, again, after a few seconds it stopped responding. Well, it was worth a shot. He said that his circuit worked fine after replacing that k resistor with a 4. May 02, Dtnf not, then I would suggest getting one of those is the first thing you should do. VegaObscura on May 02, Any questions about your particular project should be asked in the ArduinoBasics forum.

Bohdan Myroniv 25 April at These digital bits can be interface to a computer or microcontroller for further application eg. I often decoded a flow chart – it helps with the programming process. The caller will pick up the phone, giving instruction to the operator to connect their line to the destination over the other end of the telephone.

Logged asif Beginner Posts: Logic 0 ‘0’ press and hold TOE: The frequency use in the dial tone system is of audible range suitable for transmission over the telephone cable.