BORK!

I like making robots for Steampunks festivals (mostly for Steampunks at the Asylum in Lincoln). Recently, I have been updating my robot dog, Gromit.
I experimented with the DFPlayer Mini. I used it on a 5 V Arduino Uno. You need the 1 kΩ resistor because the MP3 player wants to drag the voltage down so on a 3.3 V microcontroller such as the Arduino Due, it doesn’t need it but it still works with it.
The communication between the microcontroller and the MP3 player is via serial communication so you need to put the TX of one to the RX of the other (transmitter to receiver).
I put my oscilloscope on to the speaker pins to ground and found out that the pins give the signal 180° which have a 2.5 V D.C. component so when you put the speaker on it and play nothing, both pins are almost exactly the same and therefore hardly any current flows.
In the end, I used Serial2 on an Arduino Due. I modified the source code of the example code given in the DFPlayer library and removed superfluous code as I don’t need to use SoftwareSerial.