AiKoder S3 LCD - Complete Hardware Documentation

[iuridomingos]

Hello, friends!
I recently purchased this Xiaozhi ESP32 project from AliExpress. The hardware is excellent, but the company severely limits Xiaozhi's capabilities. I've searched the repository and there's no firmware available for this specific board.
I spent an entire day investigating and reverse-engineering all possible hardware information, and I managed to gather quite a lot of useful data.
I would like to know if anyone is interested in compiling a "clean" Xiaozhi firmware for this board.
Below are all the hardware details I've collected. Thank you very much!

AiKoder S3 LCD - Hardware Configuration

Documentação extraída do firmware original da placa.

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📋 Board Information

Board: aikoder-s3-lcd
Version: 2.0
Chip: ESP32-S3
Cores: 2
Flash Size: 8MB
Minimum Free Heap: [check at runtime]
IDF Version: [from firmware]

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🔌 GPIO Pinout (Extraído do Firmware)

Display - JD9853 (SPI)

MOSI (SDA)     : GPIO38
SCK (SCLK)     : GPIO39
CS             : GPIO40
DC             : Not specified in firmware
RESET          : Not specified in firmware
Backlight      : GPIO13 (PWM)
Resolution     : 240x240
Interface      : SPI3_HOST, 40 MHz

Touch - CST816D (I²C)

Address        : 0x15
SDA            : [To be determined via I²C scan]
SCL            : [To be determined via I²C scan]
INT            : Not specified
RESET          : Not specified

Audio - ES8311 Codec

I²C Control Bus:

Address        : 0x18
SDA            : GPIO2  ✓ Confirmed
SCL            : GPIO1  ✓ Confirmed

I²S Audio Data Bus:

BCLK           : GPIO17 ✓ Confirmed
WS (LRCK)      : GPIO18 ✓ Confirmed
DOUT (Speaker) : GPIO8  ✓ Confirmed
DIN (Mic)      : GPIO7  ✓ Confirmed
MCLK           : GPIO16 (optional)
Sample Rate    : 16 kHz (default), supports up to 24 kHz
Bits per Sample: 16-bit

Power Control:

PA Control     : GPIO3 (Power Amplifier Enable - must be HIGH)
Headphone Det  : GPIO3 or GPIO40 (needs confirmation)

System

Boot Button    : GPIO0
Battery ADC    : GPIO9 (ADC1_CH8)
Charging Det   : GPIO10 (optional)

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📝 Configuration Strings (from firmware)

Display Settings

display        : [enabled]
brightness     : [0-100, configurable]
theme          : light/dark
rotation       : 0/90/180/270

Audio Settings

codec          : ES8311
sample_rate    : 16000 (or 24000)
volume         : [0-100]

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⚙️ Hardware Features (from firmware strings)

Supported Protocols

• WiFi: 802.11 b/g/n (2.4GHz)

  • Modes: Station, AP, Auto
  • Encryption: Open, WEP, WPA-PSK, WPA2-PSK, WPA2-ENT, WPA3-SAE, etc.

• Bluetooth: Supported (BT_MAC, BT_BB)

• I²C Buses: Multiple (I2C_MASTER, I2C_EXT0, I2C_EXT1)

• SPI Buses: SPI1, SPI2, SPI3

• I²S: I2S0, I2S1 (audio interfaces)

Peripherals

- UART0, UART1, UART2
- LEDC (PWM channels)
- TWAI (CAN bus support)
- USB (serial-jtag)
- SDIO_HOST
- GPIO (including GPIO_NMI)
- PCNT (pulse counter)
- RMT (remote control)
- ADC (analog inputs)
- Timers (TIMER1, TIMER2, SYSTIMER)

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🔧 Partition Table

Label          Type       Subtype    Address      Size
nvs            data       nvs        [address]    [size]
otadata        data       ota        [address]    [size]
phy_init       data       phy        [address]    [size]
model          [type]     [subtype]  [address]    [size]
app            app        [subtype]  [address]    [size]

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📚 Firmware Modules

Core Components

• esp_system: System initialization and power management
• heap: Memory allocation (DRAM, IRAM, RTCRAM, SPIRAM/PSRAM)
• nvs: Non-volatile storage
• esp_hw_support: Hardware support (clocks, interrupts, GPIO)
• freertos: Real-time operating system
• esp_timer: High-resolution timers
• newlib: C standard library
• pthread: POSIX threads

Communication

• esp_netif: Network interface
• lwip: TCP/IP stack
• esp_wifi: WiFi driver
• esp_event: Event loop
• mqtt: MQTT client
• esp_http_client: HTTP client
• esp_https_ota: OTA updates

Peripherals

• driver/gpio: GPIO control
• driver/i2c: I²C master/slave
• driver/spi: SPI master
• driver/i2s: I²S audio
• driver/ledc: PWM/LED control
• driver/uart: Serial communication
• esp_lcd: LCD panel interface (including JD9853 support)

Graphics

• LVGL: GUI library (esp_lvgl_port)
• esp_lcd_jd9853: JD9853 display driver

Audio

• ES8311: Audio codec driver
• i2s: I²S interface for audio streaming

Storage

• esp_partition: Partition management
• nvs_flash: NVS operations
• spiffs: File system

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🚀 Arduino IDE Configuration

Board: ESP32S3 Dev Module
Upload Speed: 921600
USB CDC On Boot: Enabled
CPU Frequency: 240MHz (WiFi)
Flash Mode: QIO 80MHz
Flash Size: 8MB
PSRAM: OPI PSRAM
Partition Scheme: Default 4MB with spiffs (or custom)
Core Debug Level: None

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📦 PlatformIO Configuration

[env:aikoder-s3-lcd]
platform = espressif32
board = esp32-s3-devkitc-1
framework = arduino

board_build.mcu = esp32s3
board_build.f_cpu = 240000000L
board_build.flash_mode = qio
board_build.psram_type = opi

board_upload.flash_size = 8MB

build_flags = 
    -DBOARD_HAS_PSRAM
    -DARDUINO_USB_CDC_ON_BOOT=1
    
    # Audio I²C (Confirmed)
    -DES8311_SDA=2
    -DES8311_SCL=1
    
    # Audio I²S (Confirmed)
    -DI2S_BCLK=17
    -DI2S_WS=18
    -DI2S_DOUT=8
    -DI2S_DIN=7
    -DI2S_MCLK=16
    
    # Power Control
    -DPA_CTRL=3
    
    # Display
    -DLCD_MOSI=38
    -DLCD_SCK=39
    -DLCD_CS=40
    -DLCD_BL=13

monitor_speed = 115200

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⚠️ Important Notes

Audio ES8311

• I²C Bus: SDA=GPIO2, SCL=GPIO1 ✓ CONFIRMED
• I²S Bus: BCLK=17, WS=18, DOUT=8, DIN=7 ✓ CONFIRMED
• PA Control: GPIO3 must be set HIGH to enable audio amplifier
• Chip Address: 0x18 (7-bit I²C address)
• The ES8311 requires initialization via I²C before audio playback

Display JD9853

• Uses SPI3_HOST interface
• 240x240 resolution
• Backlight controlled via PWM on GPIO13
• The command JD9853: The 3Ah command has been used appears in logs

Touch CST816D

• I²C address: 0x15
• Exact I²C pins need to be discovered via scanning
• Possible pins: GPIO4/5 or GPIO6/7

Power Management

• Battery monitoring: GPIO9 (ADC1_CH8)
• Calibration scheme detected in firmware
• Sleep modes supported

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🔍 Firmware Strings Reference

Key strings found in firmware that may be useful:

"aikoder-s3-lcd"
"Duplex channels created"
"Es8311AudioCodec initialized"
"Display: Power management not supported"
"Backlight: Set brightness to %d"
"Battery level"
"Entering Wi-Fi configuration mode"

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📖 Extracted Information Summary

✅ Confirmed Hardware

• ESP32-S3 with 8MB Flash, 2MB PSRAM
• JD9853 display controller (240x240 SPI)
• ES8311 audio codec (I²S + I²C)
• CST816D capacitive touch (I²C)

✅ Confirmed Pins

• ES8311 I²C: SDA=2, SCL=1
• ES8311 I²S: BCLK=17, WS=18, DOUT=8, DIN=7
• PA Control: GPIO3
• Display: MOSI=38, SCK=39, CS=40, BL=13
• System: Boot=0, Battery=9

❓ To Be Confirmed

• Touch I²C pins (SDA/SCL)
• Display DC and RESET pins
• Headphone detection pin
• Additional GPIO functions

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📄 Source

Information extracted from firmware.bin and system logs provided by the user.

Last Updated: November 2025