Many of us have the hobby of listening to music in leisure time. Mp3 players which are USB compatible are very useful to carry any where and listen to music at anytime.

This small sized, portable and low cost USB MP3 player, can play audio files on USB. For implementing this portable device, you just need very few basic electronics components and hence you require less assembling time.

Now we are going to design and build a compact size USB MP3 player module which can read and play the audio files stored in MP3 format on USB. This circuit uses a digital IC to convert the digital voice data into analog audio that can be heard through headphones or audio speakers

USB MP3 Player Circuit Components

• R1, R5- R7- 1.5K
• R2- R4 – 22K
• R8 – 1M
• C1, C2 – 33uF
• C3- C8 – 100nF
• Crystal Oscillator – 12MHz
• PCM2704CDB IC
• Push Buttons
• Headphones – 32ohms
• USB interface (Female)

Circuit Diagram of USB MP3 Player

USB MP3 Player Circuit Design

1. This design uses PCM 2704CDB IC chip as a heart of this circuit. This 28 pin IC is a stereo audio digital to analog converter with USB 2.0 interface compatible. This IC can operate in an adaptive asynchronous mode for playback functions. It is to be noted that it is a plug and play device which requires no software code.
2. Connect the pins of USB female connector to the respective pins of PCM 2704CDB IC (D+, D- and VBUS) making sure that D+ and D- pins are connected through 22 ohm resistor.
3. Connect each push button to Human Interface Device (HID) pins (HID0, HID1 and HID2) through 1.5K ohm resistors by making a common connection to suspend flag pin. And also connect the 12 MHz crystal oscillator and all remaining capacitors to the pins as shown in the figure.
4. Connect a headphone to headphone jack by taking inputs from Vout R (15) and Vout L (14) of the IC.
5. Connect the power supply 5V (VBUS) to the respective pins shown in the figure.

USB MP3 Player Circuit Operation

Turn ON the power supply to the circuit by giving two respective DC voltages to the pins. Once the circuit is powered, it gets audio data and control data from USB through D- and D+ pins. Due to high speed transceivers, all this data transfer is carried out at full speed.

This IC decodes the received data and converts to the analog audio which will be available at the VoutR and VoutL pins of the IC. It is also possible to increase/decrease the volume and also mute by pressing corresponding push buttons connected to HID pins.

We can also connect audio speaker in place of headphones using appropriate power amplifier circuit between Vout pins and audio speaker. We can extend this circuit for remote control operation by adding an IR sensor with the corresponding receiver circuit.

Advantages of USB MP3 Player

Portable device as it consist less number of components
Much easier construction
Facilitates headphones as well as audio speaker output
Most feasible and low cost alternative to commercial MP3 players

Note:

• +5V DC and +3.3V DC power supplies have to be derived from respective low dropout (LDO) regulators.
• Loudspeakers or Low impedance headphones must need an amplifier circuit at Vout terminals to make audio signals audible.
• It is recommended to go through the data sheet of PCM 2704CDB IC before going to build this circuit. You can download this datasheet by clicking here.