MT8870 DTMF Decoder Module - Arduino Test with PWM Audio Synth Tones

The MT8870 DTMF decoder IC runs at 5 volts, perfect for Arduino. It has 4 data outputs representing the detected touch tones, and an output to signal that data is available, which Arduino can use as an IRQ to quickly retrieve data.
This project tests the MT8870 on a PCB module connected to an Uno by generating DTMF tones from a second Uno (using a PWM audio synth library) and we can see how fast we can send tones before the decoder can't interpret them anymore.

Sketch & Wiring Diagram: https://github.com/GadgetReboot/MT8870_DTMF

Previous video with more detail about the PWM synth and DTMF generation: https://www.youtube.com/watch?v=9OtRh3_pn68

Patreon: https://www.patreon.com/gadgetreboot Pinterest: https://www.pinterest.ca/GadgetReboot Twitter: @GadgetReboot https://twitter.com/gadgetreboot ... https://www.youtube.com/watch?v=Wx6C4k_xxz0