A Simple Callback Audio Player
The example demonstrates how to implement an MP3 Player which provides the data via callbacks and sends the audio via I2S to an external DAC.
This demonstrates the minimum implementation. I recommend however to provide implementations for the other callback methods to enhance the functionality: e.g absolute positioning, file selection by name etc.
SD Card
Here is the information how to wire the SD card to the ESP32
| SD | ESP32 |
|---|---|
| CS | VSPI-CS0 (GPIO 05) |
| SCK | VSPI-CLK (GPIO 18) |
| MOSI | VSPI-MOSI (GPIO 23) |
| MISO | VSPI-MISO (GPIO 19) |
| VCC | VIN (5V) |
| GND | GND |
External DAC:
For my tests I am using the 24-bit PCM5102 PCM5102A Stereo DAC Digital-to-analog Converter PLL Voice Module pHAT
I am just using the default pins defined by the framework. However I could change them with the help of the config object. The mute pin can be defined in the constructor of the I2SStream - by not defining anything we use the default which is GPIO23
| DAC | ESP32 |
|---|---|
| VCC | 5V |
| GND | GND |
| BCK | BCK (GPIO14) |
| DIN | OUT (GPIO22) |
| LCK | BCK (GPIO15) |
| FMT | GND |
| XMT | 3V (or another GPIO PIN which is set to high) |
- DMP - De-emphasis control for 44.1kHz sampling rate(1): Off (Low) / On (High)
- FLT - Filter select : Normal latency (Low) / Low latency (High)
- SCL - System clock input (probably SCL on your board).
- FMT - Audio format selection : I2S (Low) / Left justified (High)
- XMT - Soft mute control(1): Soft mute (Low) / soft un-mute (High)