DFPlayer Mini UART Communication not working

I'm working on a project, which contains a DFPlayer Mini: Reference

However, while the I2C modules are working great, i can't get the DF to work (Serial communication). It won't recognized by the Arduino board, and it does literally nothing.

I wired the module according to the connection diagram (see Reference above), loaded up the sample code, but this gives me just "Unable to begin ..."

What i already tried:

  • At first, i'll integrated the DF module in my existing circuit; so i seperated it from this and wired it up on a breadboard (Standalone).

  • As the result was the same, i soldered the wires directly, to eliminate the "source of error" breadboard.

  • My main platform is a Teensy 2.0; however, i tried an Arduino Micro, and now a Arduino Mega 2560.

  • I bought another two DF modules and ended up having three of them, all with the same result.

  • I tried both powering the module (3.3V and 5V) from an external power source, or the Arduino.

  • Starting with SoftwareSerial, i tried (on all three boards) different TX / RX pins, using Serial1, Serial2, no luck.

  • Put a 1k resistor between RX or TX or both.

However, if i connect IO_1 and GND on the DF module (button), the LED turns on, but nothing happens.
The current setup is on the Arduino Mega, wired up DF-TX to TX1 (Pin 18), DF-RX to RX1 (Pin 19, with 1k resistor), DF-VCC and DF-GND to an external power source (5V). Also, i connected a speaker (4 Ohms, 3W) to the player. SD card (4GB) is formatted with FAT (also tried FAT32), contains a mp3 folder with three files named 0001.mp3, 0002.mp3 and 0003.mp3. The Arduino itself is currently powered by USB.

Does anyone have an idea how to get the serial communication (or the module itself) working?

Source Code only, which i used as base.

Have you tested the player using one of the provided example sketches, with no other components connected to the Arduino?

Have you tried using one of the hardware serial ports on the Mega, instead of software serial?

Did you get the replacement player modules from the same supplier as the original?

Yes, i already tried some different example sketches (also see the last link in my first post). And, as already written, i tried SoftwareSerial and Serial1, Serial2, ...

No, three different suppliers (the last one was Amazon i think).

Have you tried using the player stand-alone? I mean no Arduino (except to provide power, or use external psu), just wire up speaker & a switch to the Play/Next pin, insert sd card with mp3 file(s) and click button to play?

Okay, i created a testing circuit (see attachment) now, plugged everything in, inserted my SD card and: No sound. But: It seems to react to the IO1 and IO2 pins, so with the button(s) i can switch it on (and the LED begins to light).

How long does the led stay lit? Put just one short track/file on the SD card, play that. Does the led stay lit for the length of that track?

Yesterday i solved the problem. I bought another DFPlayer, swapped the old one out and: Problem solved. The problem was the amplifier chip, and, seems i got very unlucky, all three chips of the other DF’s don’t work as they should. However, i figured this out by using the DAC_L, DAC_R and the GND pins as output. The problem with the UART communication was a damaged resistor (I measured it and there was no connection between the pin’s).

So 3 different players from 3 different suppliers all had the same fault?

Yeah, one of the module is a "MP3-TF-16P", not a DFPlayer Mini, which seems to not support serial communication. However, the other ones are from the same manufacturer (i measured the amplifier chips), but from a different vendor.

Yeah, one of the module is a "MP3-TF-16P", not a DFPlayer Mini, which seems to not support serial communication

Same thing, I think, so would also support serial comms. Very unlucky to have 3 units with identical fault!