ESMP3

What you need

Please note: This list is a "things I used", neither "these are the best things for this stuff" nor "you can only use these things". But please be aware that using other stuff may lead to you having to make more or less easy modifications.

Prizes are more or less the cheapest I could find on Aliexpress.

What?	For what?	Price (approx)
ESP-32-WROOM-32D	Controlling everything	4€
WS1053B on a PCB with SD card slot	Play the MP3 files; provide an SD card slot	5€
MFRC522	RFID reader	1€
5V Amplifier(s) (e.g. 2x PAM-8302)	Single-channel Amplifier	2€
Speaker(s) matching your amp (e.g. 2pcs 4 Ohm 5W)	Enabling you to hear the sounds	4€
RFID tags (ISO14443A) - e.g. 10 cards	You can also get Keyfobs or stickers	4€
4 buttons	Prev/Next track, Volume up/down	1€

You'all also need an SD card, some breadboard(s), jumper cables and a soldering iron. Also, some kind of box for the finished player.

How to connect

Schematics coming soon...ish...

How to install

Format your SD card with FAT32 and put files on it: Every album has to go into its own folder in the root of the SD card. Folders and files should not contain special characters (meaning stuff like äöüß). Spaces and dashes an alike are okay. Put the SD card into the SD card slot.

Copy include/config.sample.h to include/config.h. Modify it to at least contain the correct login details for your WiFi.

The code then should compile in PlatformIO without errors.

The serial console in PlatformIO should give you more or less useful messages about what's going on. There will also be a line saying "WiFi connected. IP address: xxx.xxx.xxx.xxx" when the connection to your WiFi succeeded.

In your browser, enter "http://xxx.xxx.xxx.xxx/" (using the IP address) from above. From there you can define mappings between RFID tag IDs and folders on the SD card.

RFID-folder-mappings

Via webinterface

To create a new mapping between an RFID tag and an folder, you can use the web interface. Click the button with the cogs icon. After putting your rfid tag on the reader (and possibly removing it again), its ID will be shown in the dialog. Click the button with the arrows behind the ID to start the mapping mode.

The dialog showing all folders with media files will be shown. Click the button with the arrows behind the correct folder, to create the mapping.

Manually

Mapping are stored on the SD card in the file /_mapping.txt. Every mapping goes on its own line. Lines should be separated by \n (Unix- style line endings); the last line should also end with a newline.

Format of a line is <RFID id>=<folder>. RFID id is the UID of an RFID tag, expressed as 8 lowercase characters with leading 0 (if necessary). Folder is the foldername to play; starting with a slash and ending without one.

A valid _mapping.txt could look like this:

1a2b3c4d=/Christmas Music Vol. 17
003aab7f=/Let it go
b691a22c=/Frozen Audiobook
22cb6ae9=/Let it go

(Yes, more than one tag can map to a folder.)

Technical details

Ports

Device	Port	Connected to
VS1053	CS	16
VS1053	MISO	19
VS1053	MOSI	23
VS1053	SCK	18
VS1053	XCS	4
VS1053	XRESET	0
VS1053	XDCS	2
VS1053	DREQ	15
RC522	SDA	17
RC522	SCK	18
RC522	MOSI	23
RC522	MISO	19
AMP_L	SD	27
AMP_R	SD	26
BTN_PREV		22
BTN_NEXT		33
BTN_VOL_UP		21
BTN_VOL_DOWN		32

Buttons pull to GND if pushed -> Internal Pull-Up needed!

RFID tags

The mapping of rfid tags to files uses the ID of the tag. A file called _mapping.txt in the root folder of the SD card defines the mappings between RFID tag ids and folders to play.

The easiest way to create this file is to use the mapping functionality of the webinterface.

Special modes

You can also save data on the tags to further manipulate the system. Position of the data is irrelevant, the whole tag will be searched.

Using [random] will play the files in a random order. [random:2] will randomize everything except the first 2 files. This can be useful for having the favorite song of your kids playing, but after that getting a bit of randomness.

Using [lock] will turn this key into a key for the locking mode. Scanning the tag enables locking mode. The next album started will keep running until the end. Removing the tag will be deactivated, as are the buttons for prev and next track. You can disable locking mode by again scanning the lock tag again.

[advent] is used for christmas time. An album with this tag will only play in December. On December 1st, only track 1 will play. On December 2nd, track 2 followed by track 1. On December 3rd, tracks 3, 1 and 2. From December 24th on, track 24 followed by tracks 1-23. So your kid will get the "daily track" first, followed by all previous tags in the right order.