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ESP32 Webradio

Introduction

picture of my webradio

This project is inspired by several other internet radio projects, but all projects lacked direct output via Bluetooth speakers. The first idea came from a project published by Gerald Lechner in an article at the AZ Delivery blog. I've ported the original code from an Arduino IDE compatible structure to a PlatformIO version.

But this version suffers from a permanently interrupted tcp audio stream. So I looked for a solution to this problem and found these projects ESP32-MiniWebRadio and ESP32-audioI2S. Especially the last one contained the solution on how to optimize the tcp settings to get better streaming performance with the arduino framework - thank you Wolle for your support.

And then there was the Bluetooth challenge...

First Try: As I wanted to connect bluetooth speakers to my webradio I searched for similar projects that had done this before. I found ... nothing, but pschatzmann and his great projects/libs ESP32-A2DP and arduino-audio-tools. Finally I found his post "The ESP32 only supports either Bluetooth or WIFI, but not both at the same time. So if you use A2DP, you will not be able to use any functionality which depends on WIFI (e.g. FreeRTOS queues)" in his project wiki - dead end.

Second try: I stumbled across the KCX_BT_EMITTER in Ralph S Bacon's VLOG. I got it working, but this device couldn't pair with my Marshall Emberton II BT Speaker. It's a nice little device and it's fun to play with serial interface and these old AT+commands. Again, dead end.

Third try: I bought this little gadget ORIA Bluetooth Aux Adapter, 2 in 1 Bluetooth 5.0 to connect my BT speakers. The next picture shows how I integrated the ORIA in my case. It came with a rechargeable battery and I had to get rid of it (for details see post). The two holes at the side of the case are for the status LEDs and between the holes is the grey BT-connect push-button.

ORIA BT Adapter Integration

Fourth try: I didn't like all these solutions I've tried so far, because the audio data is converted mulitple times (D->A->D) - that is superfluous. So I continued my search. I've found & ordered the TSA5001 module that utilizes I2S as input. It works as a drop-in replacement of my PCM5102a. But I forgot, that different radio stations broadcasting with different sample rates and the TSA5001 specs are saying, it supports only one fixed sample rate:

  • Sampling Rate: 48KHz
  • Bit per Sample: 16 bit, 24bit, 32bit.
  • aptX, aptX Low Latency, aptX HD, SBC and AAC
  • Bluetooth protocol: A2DP

This works perfectly for radio stations with a sample rate of 48KHz. Streams with other sample rates (e.g. 44,1Khz or 24KHz) are played back with regular interruptions or at a wrong pitch.

To find a way to convert all radio streams to 48KHz I have to learn how to use Phil Schatzmanns Arduino Audio Tools in depth.

To remember my research results I wrote down many of the information, e.g.

Features/Requirements

  • Reliable operation
  • Easy to use
  • Good sound quality
  • Connectivity for Bluetooth speakers
  • Analog output-jack for active speakers
  • Function as clock when radio is off
  • Simple user interface in the style of old car radios
  • Visualization of information about current song and station
  • Store stations as JSON-file in mcu filesystem
  • Web-based wifi-setup
  • OTA update for firmware and radio station JSON

Components and Connections

Components used for this project

Connected GPIO pins

Pin Function Application Arduino Comment
GPIO21 SDA Disp I2C D2
GPIO22 SCL Disp I2C D1
GPIO32 DigIn Rotary 1 CLK (A) D6 select Volume
GPIO33 DigIn Rotary 1 DT (B) D5
GPIO35 DigIn Rotary 1 SW D7 add 10K Pullup Resistor
GPIO17 DigIn Rotary 2 CLK (A) select Station
GPIO14 DigIn Rotary 2 DT (B)
GPIO16 DigIn Rotary 2 SW add 10K Pullup Resistor
GPIO25 LRC PCM 5102 (I2S) I2S Amplifier
GPIO26 BCLK PCM 5102 (I2S) I2S Amplifier
GPIO27 DIN PCM 5102 (I2S) I2S Amplifier

Implementation

State Transition Model

My implementation works with different states. Events like pressing a button or a successful firmware upload triggers the transition to another state.

state transition

TODOs

Fixes

  • show upload state on display e.g. progress bar
  • fix display error when title contains "special chars"
  • handle wifi connection loss while in standby

Features

  • use F-macro and safe some RAM
  • use mini CSS lib for html
  • Change button long-press behaviour: When button is pressed long enough, the action happens without releasing the pressed button. So you don't have to count to know when it's time to release the button
  • personalized favlist
  • debug menu

Libs

Audio

Display/Graphics

Rotary Enocder

Preferences

Webserver

Protocols

SPI

Default VSPI Pins:

Function GPIO
MOSI (Master Out slave in) 23
MISO (Master in Slave out) 19
SCK (Serial Clock) 18
DC 21
RST 22
CS/SS (Chip Select) 5

Use SPI Pin Test to ask MCU for actual pins.

I2C

Default I2C pins on ESP32:

Function GPIO
SDA 21
SCL 22

Use I2C Scanner Code to test if device is detected and to get its address

Inter-IC Sound (I2S)

There are two I2S periphals on the ESP32 and "arbitrary" GPIO pins can be choosen.

Some I2S basics from Wikipedia:

Label Synonyms Function
SCK BCLK Bit clock line: Officially "continuous serial clock (SCK)".[1] Typically written "bit clock (BCLK)"
WS LRCLK, FS Officially "word select (WS)". Typically called "left-right clock (LRCLK)" or "frame sync (FS)".
SD SDIN, SDATA Officially "serial data (SD)", but can be called SDATA, SDIN, SDOUT, DACDAT, ADCDAT, etc.[3]
MC Master clock: This is not part of the I2S standard,but is commonly included for synchronizing the internal operation of the analog/digital converters.
Resources

Various ESP32 Boards

ESP32 DEV KIT C V4

ESP32 WROOM D1-MINI

PLATFORM: Espressif 32 (6.4.0) > Espressif ESP32 Dev Module HARDWARE: ESP32 240MHz, 320KB RAM, 4MB Flash

Chip is ESP32-D0WDQ6 (revision v1.0) Features: WiFi, BT, Dual Core, 240MHz, VRef calibration in efuse, Coding Scheme None Crystal is 40MHz MAC: 84:cc:a8:5e:c3:ac

Pinout

Various Displays

LCD blue 4x20 Zeichen, HD44780, I2C

The display

  • is extremely dependent on the viewing angle
  • is extremely slow via I2C
  • brightness is not changeable via I2C

OLED Color 128x128, SPI, SSD1327

OLED 128x64, monochrome, I2C, SSD1306

Eigenschaft Wert
Betriebsspannung 3.3V bis 5V
Bus I2C
Address I2C device found at address 0x3C

Variuos Amplifiers

HiLetgo PCM5102 I2S IIS Lossless Digital Audio DAC Decoder

Input via I2S

MAX98375a

Input via I2S

Various Rotary Encoders

Other ESP32-based Internet Radio Projects

ESP32 I2S amplifier (I2S -> MAX98357a)

ESP32 analog amplifier (ESP DAC -> PAM8403)

M5StickC plus (ESP32 Pico), external I²S DAC (PCM5102A)

ESP32 Internet Radio on TTGO T-Display board

  • OLED Display on Board, 8-Bit Audio? see Video

by Wolle

by Andreas Spiess

ESP32, VS1053 (MP3 Deoder), PAM8403 (digital Amp), 3,5" LCD

https://www.instructables.com/Internet-Radio-Using-an-ESP32/

ESP32 VS1053, TFT ILI9341 Touchdisplay by Ralph S Bacon

Ralph shows how he built and improved his webradio in several VLOG videos:

Lost + Found