diy mp3 player for kids
This is a simple diy mp3 player for kids. Is is based on the DFPlayer Mini Mp3 module by DFrobot wich has everything onboard. No programming required. It is a very basic build. If all parts are available it should not take longer than an afternoon to build.
Volume adjustments are done with a potentiometer. It is possible to use the prev/next buttons on the mp3 Module too. I will have maximum volume after power loss though.
| item | amount | description |
|---|---|---|
| mp3 module | 1 | https://wiki.dfrobot.com/DFPlayer_Mini_SKU_DFR0299 |
| speaker | 1 | 3 watt speaker for arduino / raspberry pi |
| resistors | 2 each | 200k, 100k, 51k, 33k, 24k, 15k, 9.1k, 6.2k, 3k |
| power source | 1 | usb powerbank or 4.5V battery compartment |
| potentiometer | 1 | 100 Ohm linear |
| jumperwires | ~25 | dupond 1pin female for buttons / powersource / potentiometer |
| push buttons | 1 - 17 | depending on how many songs and functions you want to use |
| copper wire | 1 | for ground connection between the buttons |
| pin header | 2 | 1 x 10 for buttons |
| pin header | 2 | 1 X 8 male for mp3 module out |
| pin header | 2 | 1 x 8 female for mp3 module (optional) |
| microSD card | 1 | fat16/fat32 up to 32GB |
| box | 1 | any box will do, wood, 3dprinted,... |
The pin headers for the mp3 module are not really needed. You can just solder ist right onto the pcb. But for some reason i like the idea of beeing able to replace it without soldering.
Not all output pins of the mp3 module are used in this build. But it is just more convinient to solder on strip of pin headers.
As with the pin headers, not all resistors are needed. Just for expandability they are just included.
Plug in with the text readable, tf-slot facing south.
Finding the right Power supply was not easy. Three AAA Batterie do the job, but are slowly drained by the modules standby curtent (~20mA). Using a usb power bank seemed to be logical. Unfortunately most power auto power off if the load is not above a certain limit. The module draws about 100 mA while playing. Fortunately some power banks do have a lower limit and stay ON while playing. I had good results with cheap power banks that have no button. One hat a MP3401A chipset.
With push buttons you can access a maximum of 14 Songs, usefull control keys are play/pause, next/volume up , previous/volume down. You can add 'hidden tracks' by having more songs than buttons. These can be accessed via the 'next' button.
- Power cable assembly VCC (red) into VCC
- Power cable assembly GND (black) into GND on the left
- Speaker assembly red into SPK_1
- Speaker assembly black into SPK_2
| Cable | Pin | MODULE | PIN | Cable |
|---|---|---|---|---|
| Power cable red | VCC | MODULE | BUSY | NC |
| NC | RX | MODULE | USB- | NC |
| NC | TX | MODULE | USB+ | NC |
| NC | DAC_R | MODULE | ADKEY_2 | Button # 05 |
| NC | DAC_l | MODULE | ADKEY_1 | Button # 01 |
| Speaker cable red | SPK_1 | MODULE | IO_2 | NC |
| Power cable red | GND | MODULE | GND | Button cable black |
| Speaker cable black | SPK_2 | MODULE | IO_1 | NC |
| ADKEY # | Resitor | Button # |
|---|---|---|
| 1 | 33k | Play/Pause |
| 1 | 9.1k | 04 |
| 1 | 6.2k | 03 |
| 1 | 3k | 02 |
| 2 | 200k | 14 |
| 2 | 100k | 13 |
| 2 | 51k | 12 |
| 2 | 33k | 11 |
| 2 | 24k | 10 |
| 2 | 15k | 09 |
| 2 | 9.1k | 08 |
| 2 | 6.2k | 07 |
| 2 | 3k | 06 |
Use the pinmap: https://wiki.dfrobot.com/DFPlayer_Mini_SKU_DFR0299 as reference. (NC = Not connected)
The Order in which the files are copied onto the microSD card defines which button they are assigned to. i.e. the first file is Segement 1.
To prepare the PCB disconnect 7 lines on as show here:
Place the pin headers:
Solder pin headers:
PCB with all parts soldered in (as seen from above).
PCB with the mp3 module plugged in and external components (as seen from above).
- soldering iron
- wire cutter
- utility knive
- drill
https://github.com/ghmartin77/KidsMP3Player + atiny
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