CYD Internet Radio with the ESP32-8048S043C (capacitive touch)

This is a port of my Internet Radio with the ESP32-2432S028R with resistive touchpad to the ESP32-8048S043C module with larger screen and capacitive touchpad.

Graphical User Interface

The user interface should offer the following options:

• Display of time and date
• Display of metadata such as composer and music title
• Display of station number and name
• A button to mute
• Volume adjustment via slider
• Navigating through the predefined station list
• Saving and recalling the preferred station and volume
• Saving a screenshot to SD card

To be able to display umlauts in German metadata, a character set is required that also contains the characters from 128 to 255. Such a font can easily be created from any ttf font with the program fontconvert and ttf fonts are found under Windows in the font directory. But any existing copyright must be respected!

                                        size first last  destination
fontconvert c:\windows\fonts\calibri.ttf 8    32    255 > calibri.h

Connectors on the ESP32-8048S043

We need 3 GPIO pins for the external I2S decoders. However, only the following are available on the external connectors:

Connector P1   Connector P2 used for            Connector P3 used for
  GND            GPIO_19    i2c sda               GPIO_17    free
  RXD            GPIO_11    spi mosi SD card      GPIO_18    free
  TXD            GPIO_12    spi sclk SD card      GPIO_19    i2c sda
  5V             GPIO_13    spi miso SD card      GPIO_20    i2c scl

Using the 3 SPI pins from port P2 for the I2S audio, we can no longer control the SD card. If we use the 2 free GPIOs from port P3, we are still missing one pin. This means we cannot operate I2S audio and the SD card at the same time.

But the following scenario works: For the I2S audio, we use the two free GPIOs from connector P3 and one GPIO from connector P2, e.g., GPIO_11, which is otherwise used for SPI. If we now want to save a screenshot to the SD card, we stop the audio, i.e., release GPIO_11, start SPI, and save the screen data to the SD card. We then stop SPI and restart the I2S audio.

External Amplifier

To operate two speakers, I used two Max98357 PCM Class D amplifiers and equipped them with two different resistors to get the left and right stereo channel. I have described how these resistance values are calculated in my repository ESP32Internetradio.

MAX98357A

I wired the CYD and the MAX98357 as shown in the table:

MAX98357	¦	Con P1	¦	Con P2	¦	Con P3
LRC	¦		¦	IO 11	¦
BCLK	¦		¦		¦	IO 17
DIN	¦		¦		¦	IO 18
GND	¦	GND	¦		¦
Vin	¦	5V	¦		¦

                       .-----------------. 
            11 -->     o LRC             |  
            17 -->     o BCLK       MAX  |
            18 -->     o DIN       98357 |
                       o Gain            |   Spkr right
   5V Vin ---[560K]----o SD              |    _/|
           GND -->     o GND             o---|  |
           5V  -->     o Vin (5V)        o---|_ |
                       `-----------------´     \|   
                       .-----------------. 
            11 -->     o LRC             |  
            17 -->     o BCLK       MAX  |
            18 -->     o DIN       98357 |
                       o Gain            |   Spkr left
   5V Vin ---[180K]----o SD              |    _/|
           GND -->     o GND             o---|  |
           5V  -->     o Vin (5V)        o---|_ |
                       `-----------------´     \|

Connecting to the WLAN

When the web radio is put into operation for the first time, the AutoConnectAP access point is started. Log in here with your cell phone and then enter the SSID and password of your router via the web browser at the URL 192.168.4.1. The login data is then saved permanently so that the web radio connects automatically in future.

Software

I use the LovyanGFX library for programming graphical elements. I programmed some components for the user interface myself and compiled them in the UiComponents library. For the audio functions, I planned to use Phil Schatzmann's AudioTools. However, I encountered problems with both libraries, namely the following:

• The LovyanGFX calls the unsupported function
  gpio_hal_iomux_func_sel(GPIO_PIN_MUX_REG[pin], PIN_FUNC_GPIO)
  which i had to replace with
  gpio_iomux_out(pin, PIN_FUNC_GPIO, false)
  The file in question, Bus_RGB.cpp, is located in my file hierarchy in this path
  ...pio\libdeps\esp32-8048S043C\LovyanGFX\src\lgfx\v1\platforms\esp32s3\Bus_RGB.cpp line 98
• The AudioTools require Arduino-ESP32 Core version 3.x, so I had to update my Platformio programming environment. To do this, I downloaded the Platformio extension pioarduino and added this line to platformio.ini platform = https://github.com/pioarduino/platform-espressif32/releases/download/stable/platform-espressif32.zip.