DFPlayer Mini module and the SDA

I saw some projects that were using this module, so I also gave it a try. And the result?

I'd buy that for a dollar!

Basically DFPlayer Mini is the ESP 8266 of MP3 playback. It is MP3 player in one small module, it can play audio files (mp3, wav) from its SD card (or USB flash drive) directly to your headphones. Module can be controlled over its serial interface or directly with buttons. There are some limitations, like that the player needs specific file structure and file naming on the storage media and somewhat poor documentation. There are few arduino libraries for it and the protocol is simple.

Getting it running

After a bit of struggle with error code 04, that was not mentioned in a datasheet that I had, I googled a bit and found datasheet for the FN-M22P Embedded MP3 Audio Module which looks like it is using the same protocol as DFPlayer. Datasheet for FN-M22P actually mentions all error codes and is written in normal English. The only difference between the FN-M22P and DFPlayer I found is that the DFPlayer does not support commands without checksum (but I did not try everything).

Hardware is held inside improved version of the addon case used in the GPS module. It is more sturdy and holds better on the PDA. Inside there is just the DFPlayer with its DAC pins connected to 3.5 jack. Its control app is written in 120 lines of SVS. It is quite limited in its functionality and it has no idea what is the state of the module. It is good for now but there is also space for some improvements.

Performance

The DFPlayer just works enough to be usefull. You do not have much control over the playback, you can't read metadata from the songs or do anything with the files. In my case the sound quality is good but not great, there is always a quiet hiss that can be heard if you focus on it. It could come from power supply of my PDA, but I don't have the equipment to pinpoint source of that distortion.