Using Cheap Asian Electronic Modules Part 21: by Jim Rowe
Stamp-sized digital
audio player
The DFPlayer Mini is a low-cost digital audio player module. It’s available
from popular Internet suppliers, including uk.banggood.com and Amazon.
co.uk, as well as marketplaces like eBay and AliExpress, for a couple of
pounds, including postage. Despite its size and price, it can do a lot!
T
he DFPlayer Mini is a very
flexible module with a great
many features. I was impressed
after trying the module out for myself.
One of the best things about it is
that it plays several different audio
file formats, including MP3, WMA and
WAV, in mono or stereo, and it can read
those files off either a microSD card or
USB Flash drive with a capacity up to
32GB in either case. But it has a lot of
other features, so let’s take a look at the
hardware involved and how to drive it.
What’s inside the module
Circuit diagrams for the DFPlayer Mini
module are surprisingly hard to find,
but an examination of the module
reveals that it’s based on two ICs: a
YX5200-24SS (IC1) which does most
of the work and a smaller 8002 audio
amplifier chip (IC2).
While data sheets for both devices
are available, the sheet for the YX520024SS is almost entirely in Chinese. But
I was able to glean enough info to draw
the module’s internal block diagram,
shown in Fig.1.
The YX-5200 chip is the module’s
brains. Inside it, there’s a 16-bit MCU
(micrcontroller), an analogue DSP (digital signal processor), EPROM and Flash
memory, a 24-bit stereo DAC (digitalto-analogue converter), a serial UART
for communication with an external
MCU, and ports to communicate with
a microSD card or a USB thumb drive.
All this in a compact 24-pin SSOP
(SMD) package – it’s virtually a complete digital audio system on a chip!
The YX-5200 chip can play back
MP3, WMA and WAV files at sampling rates of 8kHz, 11.025kHz, 12kHz,
16kHz, 22.05kHz, 24kHz, 32kHz,
44.1kHz or 48kHz.
It can handle files on either microSD (‘TransFlash’ or TF) cards or
USB thumb drives with capacities up
to 32GB, formatted with a FAT16 or
FAT32 file system.
You can store up to 45 hours of CDquality WAV files on a 32GB card/drive,
or about 23-days worth of 128kbit MP3
files – a lot!
The 24-bit stereo DAC in the YX5200 is claimed to provide a dynamic
range of 90dB, with a signal-to-noise
ratio (SNR) of 85dB. That isn’t exactly
HI-Fi, but it isn’t too bad either.
The built-in MCU and DSP combine
to provide features like audio gain adjustment over 31 levels and the ability to select one of six playback tonal
equalisation settings.
You can also select the playback
mode (normal/repeat/folder repeat/
single repeat/random) and the playback
source (USB drive, microSD card or a
couple of other options).
It also provides a BUSY logic output signal which is at logic-low level
(<800mV) when playing a file, rising to
logic high (~3.5V) when playback stops.
Turning to IC2, its operation is
quite straightforward. Housed in an
8-pin SOIC package, it’s basically just
a low-power audio amplifier with a
few extras.
Running from 5V, it can deliver
up to 2W into a 4Ω loudspeaker load
with 10% total harmonic distortion
(THD+N), or 1.5W into an 8Ω load with
1% THD+N.
It provides a push-pull (bridged)
output, and no output coupling capacitors, snubber network or bootstrap capacitors are needed. It’s also unity-gain
stable, has an externally programmable
gain and includes circuitry to suppress
clicks and plops during power on/off.
As you can see from Fig.1, the DFPlayer Mini module makes good use of
the many features provided by both ICs.
As well as providing all of the main
control inputs needed by IC1, it also
features a microSD card socket on the
top of the module connected directly
to IC1. The latter’s BUSY signal output
is brought out to a pin and also drives
LED1, a tiny blue SMD LED.
The left and right channel outputs from the YX5200’s DAC are also
Views of the top (left) and bottom of
the DFPlayer Mini module with a
microSD card inserted. It is shown at
close to double life size for clarity.
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Practical Electronics | February | 2020
Features and specifications
n Just 21 × 21 × 12mm including microSD card socket and pin headers
n Plays MP3, WMA and WAV audio files (4.3 filenames)
n 24-bit stereo DAC
n Built-in 2W mono bridge-mode amplifier
n Plays files from microSD cards or USB Flash drives (up to 32GB)
n Multiple control options, from just four pushbutton switches to full serial
mode control from a microcontroller (eg, Arduino or Micromite)
n Line-level stereo outputs which can also drive headphones
n Six playback equalisation options: Normal (flat), Pop, Rock, Jazz, Classical
and Bass
n Programmable playback volume in 31 steps (0-30)
n Runs from a 3.3-5.2V supply, drawing 25mA when idle or 200-250mA
during playback.
brought out for use in driving either
headphones or an external amplifier, in
addition to being mixed together and
fed into IC2 to drive a speaker directly.
No socket is provided for plugging in
a USB thumb drive – just a couple of
pins identified as ‘USB−’ and ‘USB+’.
I couldn’t find any information on the
use of these pins anywhere in the commonly available data sheets for the DFPlayer Mini module, but I guessed that
these could be connected to the D– and
D+ signal lines of a USB socket, and as
you will see later, I was right.
Fig.1: block diagram of the DFPlayer
Mini audio player module.
show how it can be used to drive either stereo headphones or line-level
outputs to an external stereo amplifier
or HI-Fi system.
Returning now to Fig.3, which shows
the simple four-pushbutton control
scheme, S1 and S2 have dual functions
in this mode. A short press is used to
move to the previous track (S1) or the
next track (S2), while a longer press
either decreases (S1) or increases (S2)
the volume. S3 and S4 each have only
single functions, to start playing the
first track (S3), or the fifth track (S4).
The more complex pushbutton control arrangement of Fig.4 is a bit more
tricky. To allow twenty pushbuttons to
be connected using just two pins, each
Putting it to use
Fig.2 shows how to wire up the DFPlayer Mini module. The speaker (if used)
connects directly between the SPK_1
and SPK_2 pins (6 and 8) while the
module’s power supply (3.3-5.2V DC) is
fed to pin 1 (VCC) and pins 7/10 (GND).
The total current requirement is
around 25mA when idle, rising to
around 200-250mA during playback.
The module can be used as a self-contained audio player, controlled using
just four SPST pushbutton switches,
connected as shown in Fig.3. Alternatively, a much larger array of 20 pushbuttons can be connected, as shown
in Fig.4.
Otherwise, its operation can be controlled entirely from an Arduino, a Micromite or many other kinds of microcontroller, using the UART serial port
lines at pins 2 (RX) and 3 (TX), along
with the BUSY signal from pin 16. This
configuration is shown in Figs.5 and 6.
The rest of the connections are to
make use of the module’s extra features.
For example, you can use it to play
files from a USB thumb drive by connecting up a Type A USB socket as
shown at the top right of Fig.2, with pin
1 connected to the +5V supply, pins 2
and 3 to pins 15 (USB–) and 14 (USB+)
of the module, and pin 4 to the module
ground (pins 7 or 10).
The dashed connections to pins 4
(DAC_R) and 5 (DAC_L) of the module
Fig.3: the simplest method of controlling the DFPlayer Mini module is by using
four pushbutton switches. Track 5 is equivalent to 005.mp3 (four characters at
most for a filename, three for the extension); folders are named 01 to 99.
Practical Electronics | February | 2020
39
Fig.2: This shows how to connect the audio player module for playback to a
speaker, headphones or other audio devices via the level outputs.
Press S1: previous track
Hold S1: increase volume
Press S2: next track
Hold S2: decrease volume
Press S3: play first track
Press S4: play fifth track
Fig.4: a more complex method for control involves 20 pushbuttons,
each with a series resistor (except S10 and S20). S7-20 just allows
playback of tracks 1-14 directly (holding the switch will cause it to
repeat indefinitely), while the rest of the switches are for playback
functionality with S5/6 identical to S1/2 in Fig,3.
Switch functions:
S1 – single track/continuous playback
S2 – change playback source (USB/SD/SPI/sleep [none])
S3 – loops the current track
S4 – pause/play
of the ten pushbuttons in a given ‘bank’
has a different resistor value connected
in series.
The chip then measures the current
sunk from pin 12 or 13 when a button
is pressed, and depending on what
range it is in, it knows which button
was pressed.
In this mode, most of the extra
switches (S7–S20) are simply used to
allow direct selection of tracks to play.
Switches S5 and S6 basically duplicate the actions of S1 and S2 in Fig.3,
while the first four switches (S1–S4)
allow control over the playback mode
(single track/continuous), playback
source (USB/SD/SPI/SLEEP), enable
‘loop all’ mode and provide the pause/
play function.
Controlling it with a micro
Hooking the DFPlayer Mini up to a microcontroller is simple, thanks to the
module’s built-in UART serial port.
You just need to connect the module’s
RX input (pin 2) to the serial TX output
of the micro and connect the module’s
TX output (pin 3) to the serial RX input
of the micro. The GND of the module
(pin 7 and/or 10) also needs to be connected to the micro’s ground network.
The module’s UART is pre-programmed to communicate at 9600
baud, with the basic 8N1 protocol. It’s
also a good idea to link the module’s
BUSY output (pin 16) to a digital input
on the micro so that the control program
can tell whether the module is playing
a file or has stopped.
Arduino specifics
Fig.5 shows the connections for controlling the module from an Arduino.
It’s powered from the Arduino’s 5V
supply, which is fed to its VCC pin (pin
1). For serial communications, we’re
using Arduino digital I/O pins 10 and
11, which are driven by the SoftwareSerial library code.
The D11 digital output is connected to the RX pin on the module via
a 1kΩ series resistor. That’s because
the module inputs can handle a 3.3V
signal while the Arduino pins have a
5V swing.
The resistor limits the current into
the module’s RX pin to a reasonable
level (less than 2mA) when D11 is
driven high. The only other connection
needed is between pin 16 of the module
(BUSY) and D3 of the Arduino, for the
reasons described above.
For clarity, Fig.5 does not show, for
example, a USB socket, headphone
socket or line outputs, which were
shown in Fig.2. But these can certainly
be included if you need those functions.
There are many different libraries
and sketches on the Internet which
show how to drive the DFPlayer Mini
from an Arduino, although some are a
bit flakey and/or hard to understand.
But one of the best is from the manufacturers themselves, DFRobot and is
called DFRobotDFPlayerMini-1.0.3.zip
– it includes a set of example sketches
and you will find a link to download
it below.
Fig.5: wiring diagram for
the audio player module
when connected
to an Arduino.
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Practical Electronics | February | 2020
Screenshot of the MMBasic example
program running on a Micromite.
Driving it from a Micromite
If you’re one of the many Micromite
enthusiasts, Fig.6 shows the basic
connections needed to control the
DFPlayer Mini module from a Micromite Backpack.
The arrangement is very similar to
that for the Arduino. The module’s RX
(2) and TX (3) pins are connected to
pins 9 and 10 of the Micromite respectively, again with a 1kΩ series resistor
in series with the line to the module’s
RX pin.
Pins 9 and 10 of the Micromite are
the TX and RX pins for the Micromite’s
COM2 serial port. The remaining connection is from the BUSY pin (16) of
the module to pin 24 of the Micromite,
again to provide a playing/not playing signal. And again, for clarity, Fig.6
leaves out any extra connections you
may wish to make to the DFPlayer Mini
module, like those shown in Fig.2.
I couldn’t find any pre-existing Micromite programs to control a DFPlayer
Mini, so I wrote one myself, after studying the YX5200-24SS data sheet and
some Arduino library files. The program is called DFPlayerMini control
program.bas and is available from the
February 2020 page of the PE website.
It’s designed to run on the LCD BackPack (see May 2017 and May 2018).
As you can see from the screen grab
of the LCD touchscreen, the program
gives you a set of six touch buttons
labelled PLAY, PAUSE, PREV, NEXT,
VOLUME (down) and VOLUME (up).
Touching any of these buttons makes
the Micromite send a command to
the module to achieve the desired response, similarly to how the hardware
switches shown in Fig.3 work.
Now this MMBasic program is pretty
simple, but it should give you a good
starting place for writing more elaborate
programs yourself. With the technical
information on the DFPlayer Mini module in this article, you should be able
to get the module performing all kinds
of impressive tricks!
www.poscope.com/epe
Handy links
Module information and software:
http://bit.ly/pe-feb20-dfp1
Software library and sketches:
http://bit.ly/pe-feb20-dfp2
Documentation and Arduino library:
http://bit.ly/pe-feb20-dfp3
Reproduced by arrangement with
SILICON CHIP magazine 2020.
www.siliconchip.com.au
- USB
- Ethernet
- Web server
- Modbus
- CNC (Mach3/4)
- IO
- PWM
- Encoders
- LCD
- Analog inputs
- Compact PLC
- up to 256
- up to 32
microsteps
microsteps
- 50 V / 6 A
- 30 V / 2.5 A
- USB configuration
- Isolated
PoScope Mega1+
PoScope Mega50
Fig.6: wiring diagram of the audio player
module connected to a Micromite.
Practical Electronics | February | 2020
- up to 50MS/s
- resolution up to 12bit
- Lowest power consumption
- Smallest and lightest
- 7 in 1: Oscilloscope, FFT, X/Y,
Recorder, Logic Analyzer, Protocol
decoder, Signal generator
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