How to Use the MT8870 DTMF Decoder with a PICAXE Microcontroller

Published at : 23 Dec 2025

In this second part of my Animatronic Frog series, I explain how to use the MT8870 DTMF decoder module with a PICAXE microcontroller.

This is the same setup my animatronic frog uses to understand commands hidden in MP3 audio files. One stereo channel of the audio contains DTMF tones — and this module decodes those tones so the PICAXE knows what to do.

In this video, I go over:
• What the MT8870 DTMF decoder does
• How to wire it up to a PICAXE 14M2
• How to read its digital outputs in code

This is the link between the audio player and the servo controller that brings the frog to life!

In the next video, I’ll cover how the PICAXE interprets those decoded tones and sends commands to the servo controller through I²C.

🐸 Watch Part 1 here: “How to Control the SparkFun MP3 Player Shield with a PICAXE”
🐸 Coming soon: Part 3 – Servo Control with I²C


Parts used in this project:
• MT8870 DTMF Decoder Module
• PICAXE 14M2 Microcontroller
• SparkFun MP3 Player Shield (MY1690X-16S)
• Servo Controller (I²C)

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