MT8870 DTMF Decoder Module is a very tiny module that is based on MT8870 DTMF decoder ic. The module offers a 3.5mm audio connector to connect an audio source. The DTMF Signal in the audio source is decoded and the digital outputs on the module, indicate the key pressed. You may connect a phone to the module and the module will output the key(0-9, *, #, A, B, C or D)pressed on the audio source. This module is suitable for modem interfaces, mobile radios and other DTMF related applications. Can be used to build mobile controlled robots, home automation projects, IVR style applications, etc 

This component is ideally suited to adding dual tone multi-frequency (DTMF) decoding to your project. This detection module interprets the incoming tone and produces a coded output that can be connected to all manner of microcontrollers.

DTMF is commonly found in touch tone devices such as a phone. The tone is a combination of two separate sine waves that produce a unique signal that can be transmitted or heard. When the module receives the signal it is able to decode it and produce a binary output that can be used in other devices. The module shows the state of the signal through onboard LEDs.

As an idea, you can connect up a mobile phone via 3.5mm to 3.5mm cable to the module. Dialling into the phone from a second mobile and then using the keypad will produce the tones on the original phone. The tones in the call can then be interpreted by the module, allowing you to control all manner of projects. The pins are suited to standard sockets with a pin pitch of 2.54mm.

The MT8870 Tone Decoder is a kind of commonly used multi-frequency decode IC product developed by the MITEL company. It is a complete DTMF receiver. After it received the DTMF signal, it will divide the signal into high-frequency group and low-frequency group and send the signal to the digital decoder which can figure out the key value then send it to the outside Bus via four lines( Q1, Q2, Q3, Q4) as the binary form.

Specifications :-

• Working voltage: 5V
• Power Consumption: 500MW(MAX)r: 500 mw (MAX)
• On-board voice input interface
• On-board LED, it is very convenient to check the output state.
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• Onboard 5 x LED indicators for easy viewing output state
• Operating Temperature : -40-+85 °C
• IO Drive : Current Maximum 10mA.
• PCB Size : 25.4x25.4MM
• This decoding module is for mobile and fixed telephone voice dialing decoding function
• Designed specifically for ARDUINO Board. Can also be used for other MCUs(AVR PIC MSP430 STM32 ARM7/9/10/11 FPGA/CPLD)
• Low power consumption
• Internal gain setting amplifier
• Adjustable guard time
•  Central office quality
• Onboard 3.5mm input interface
• 5 Channel interface
• On-board MT8870 frequency decoder chip
• Power-down mode
• Inhibit mode
• Does not require external circuits or wiring, it can be inserted directly into the UNO/MEGA2560/DUE board to use.
• 12-Digital outputs decode mobile and fixed telephone keys (0-9, * #). Also, another 4 Digital output(ABCD) can use “DTMF Dial” for Software control.