WTV020 Based MP3 Type Audio playback Module (HCMODU0072)

All modules related to sound (recoding/playback, amplifiers, speakers etc.)
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WTV020 Based MP3 Type Audio playback Module (HCMODU0072)

Post by admin » Thu Sep 18, 2014 1:18 pm


The WTV020 module (HCMODU0072) is based on the WTV020SD-20 device and allows for direct playback of audio files stored on a microSD card. The module also has outputs that will either drive an 8ohm speaker connected to the SPK+ and SPK- pins, or drive a single ended amplifier directly from its DAC output via the AUDIO-L pin. There are also several options for controlling playback including interfacing push buttons for play/pause, track forward/backwards and volume up/down. Alternatively the module can be controlled via a two wire serial interface (clock and data) that allows for random track selection and playback control.

Please note: The digital pins are not 5V tolerant. If interfacing to a 5V microcontroller, the datasheet recommends using 470R resistors between the microcontroller and this module. Alternatively a level shifter or potential divider can be used. MP3 format files will need to be converted to AD4 format for playback.

Supports up to 1GB microSD cards.
Supports 4 Bit ADCPM format files.
Sampling rate from 6KHz to 36KHz for AD4 file format.
Sampling rate from 6KHz to 16KHz for WAV file format.
16 Bit DAC / PWM audio outputs,
Key (push button) mode, MP3 mode and two line serial interface mode.
Working voltage: 2.7 to 3.5V DC. 3.3V recommended.
Quiescent current: 3uA


Standalone push button example:

Two line serial example:



Why does my audio sound distorted?
It is likely that the volume level in your audio files is too high. You can reduce the level using a feely available program such as Audacity.

I am trying to play a particular audio file but it always stops in the middle of play back. Why is this?
This can also be caused by the audio level being too high.
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Re: WTV020 Based MP3 Type Audio playback Module (HCMODU0072)

Post by brumster » Tue Oct 13, 2015 4:56 pm

Worked a treat first time. As per the comments on the shop page, memory card needs to be FAT format (2GB card worked fine for me so don't worry about the apparent 1GB limitation). Filenames should be like "0000.ad4", file format 16-bit PCM @ 32000Hz *mono* WAV converted to AD4 format. Bob's your uncle ;)

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Re: WTV020 Based MP3 Type Audio playback Module (HCMODU0072)

Post by andrew » Wed Oct 14, 2015 3:09 pm

Thanks for the feedback on the SD card. I suspected that it could work with larger than 1GB but this is what the manufacturer specs it at.
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Re: WTV020 Based MP3 Type Audio playback Module (HCMODU0072)

Post by brumster » Sun Oct 30, 2016 6:30 pm

I've just revisited this for a little Halloween project (PIR-triggered speaker in the garden for approaching trick-or-treaters!!!) and have found a few more useful tips for people.

Firstly, the audio file formats - I've found that 32kHz sample rate isn't actually very repeatable; it often plays the audio on the first request but then won't play any further files unless you reset the entire device. Moving to a 16kHz sample rate fixed this. So, in summary :

- Take your file, load it into Audacity (whatever it may be - MP3, WAV, etc)
- Tracks -> Stereo Track to Mono
- Tracks -> Resample, choose 16000Hz
- Effect -> Normalize, Normalize max amplitude to -12.0dB (particuarly for loud files; fiddle with values as necessary)
- File -> Export Audio, choose WAV (Microsoft) signed 16bit PCM

Now move to the "USBRecorder" SOMO tool to convert to AD4 file format, and covert to 16000Hz again.

Do NOT bother with the command-line "AD4CONVERTER.EXE", I could not get this to create reliable files.

Name 0000.ad4, 0001.adr and so on...

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