Toys have come a long way from basic dolls and wooden blocks. In today's technology-savvy world, electronic toys have become an integral part of children's play. This includes interactive tablets, electronic games and robotic devices. Many toys incorporate sophisticated technologies to engage, educate and entertain children.
One of the features of many modern toys is audio. From upbeat tunes for babies to interactive conversations on educational devices, audio can offer an enhanced play experience and profoundly impact a child's development in terms of vocabulary, pronunciation and conversational patterns.
Some modern toys also stimulate cognitive development by introducing rhythm, patterns and cause-and-effect relationships, encouraging problem solving and critical thinking. Toys with laughter or soft lullabies can help children express and understand their emotions, which is often comforting for babies and young children. Audio elements in toys can encourage creativity and imaginative play. Children often incorporate sound effects and voices into their stories and pretend play, enhancing their storytelling and role-playing experiences.
Typical audio features include musical toys, sound effects, educational audio, interactive dialogue, and storytelling. To incorporate audio into a toy's design, an MP3 player or decoder is required. MP3 decoders can add sound effects, music, dialogue, stories, or audiobooks to toys. One of the cheapest MP3 decoders used for this purpose is the GPD2856. In this project, we will play multiple audio files using a GPD2856 MP3 decoder. The decoder IC can play MP3 audio files from a Micro SD card or USB flash drive.
Required components
1. GPD2856 MP3 decoder board
2. speakers
3. microSD card or USB flash drive
4. Connecting wires
CI GPD2856
The GPD2856 is an MP3 decoder chip developed by Generalplus Technology. It's a low-cost, low-power chip that can create MP3 players, car stereos and other audio devices. It supports many MP3 encoding formats including MP3, WMA, WAV, AAC and multiple playback modes including sequential playback, random playback and repeat playback.
The chip can drive a pair of speakers directly with an integrated amplifier. It also has a headphone jack for connecting headphones or an external amplifier. Various sources, including a lithium battery, USB port, or car adapter, can power the GPD2856. It is also compatible with various storage devices, including TF cards and USB flash drives.
The GPD2856 is popular among hobbyists and makers who want to build an MP3 player or other audio device. It is also used in many commercial products, including car stereos and portable speakers.
The pin diagram of IC GPD2856A.
The GDP2856A is a single-chip MP3 player solution. It is used in FM radio MP3 player applications and operates with RDA5807, BK1080 and RTC6207E single-chip FM radio solution ICs. The chip also has an audio equalizer function that can switch between normal, classic, bass, live, rock and pop. However, this mod requires additional resistors and a switch.
Keyboard decoding for the chip.
The GDP2856A is a single-chip MP3 player solution. It is used in FM radio MP3 player applications and operates with RDA5807, BK1080 and RTC6207E single-chip FM radio solution ICs. The chip also has an audio equalizer function that can switch between normal, classic, bass, live, rock and pop. However, this mod requires additional resistors and a switch. Keyboard decoding for the chip is shown in the image below.
The complete circuit diagram to build an MP3 decoder using GPD2856.
On the GPD2856, pin 8 (AD key) decodes the switch input. Each switch has a resistor associated with it and they all form half of a voltage divider network with resistor R17. Typically, an analog-to-digital converter (ADC) is used for this type of input.
GPD2856C MP3 decoder board
Fortunately, not all of these circuit connections need to be made. An MP3 decoder board based on the GPD2856 is commonly available. One of these decoder boards is shown in the image below.
The GPD2856C MP3 decoder board.
This MP3 decoder board can play MP3 files from a USB flash drive or MicroSD flash memory card. The player has a built-in 2W mono amplifier, which produces decent sound quality even if the speakers are connected directly to the speaker terminals. It has a 3.5mm gold-plated headphone jack that can connect headphones or an external audio amplifier.
The board has a MicroUSB port, so a regular MicroUSB cable (cell phone) can power the board. There are also solder terminals for connecting a 3.7V lithium battery. The battery connectors can support up to 5.5V DC. The 3.7V lithium battery connected to the device can be charged by applying power to the MicroUSB connector.
Note: Some flash drives require a minimum voltage of 5V and will not work with a 3.7V power supply.
The player supports files stored on a USB flash drive (up to 32 GB) and a MicroSD flash card (up to 16 GB). The SD card will play first if both are connected, but the “mode” button can override this.
Audio will play automatically when turned on. The chip searches root directories to find MP3 files.
The pin diagram of the decoder board.
Circuit Connections
The GPD2856 MP3 decoder board is readily available in the market. After configuring the board, connect the speakers directly to the board's speaker terminals. Download some MP3 files to a MicroSD card or USB flash drive. Connect a memory card to the TF card slot and/or a USB flash drive to the USB port. Power the board using a 3.7V lithium battery or mobile charger.
How it works
The MP3 decoder board will play audio files loaded on the TF card whenever it is turned on. If the TF card is inserted after the board is turned on, the audio files will be played as soon as the card is inserted. If a MicroSD card and USB flash drive are inserted, the decoder card plays music from the SD card by default.
USB and MicroSD can be switched by short pressing the P/P mode button. When an MP3 is playing, the red LED flashes.
- The next track can be selected by quickly pressing the Next/V++ button
- To increase the volume, hold down the Next/V++ button for a little longer
- To navigate to the previous track, briefly press the Prev/V– button.
- To increase the volume, hold down the Next/V++ button for a while
- To repeat a single track, press the “Repeat” button.
Results
Check out the video here.
