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📚 AMBA Project - Complete Technical Documentation

🎯 Project Overview

AMBA (Adaptive Musical Box with AI) คือระบบเครื่องดนตรีอัจฉริยะที่ผสานระหว่าง ESP32 (Embedded System) และ Raspberry Pi (AI Server) เพื่อสร้างดนตรีแบบ real-time ด้วย AI

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📋 Table of Contents

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Architecture Overview⁠

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ESP32 Embedded System (Detailed)⁠

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Raspberry Pi AI Server (Detailed)⁠

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Markov Chain Music Generation⁠

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Cloud Deployment⁠

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Advanced Embedded Concepts⁠

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🏗️ Architecture Overview

System Architecture

┌─────────────────────────────────────────────────────────────┐

│ AMBA SYSTEM ARCHITECTURE │

├─────────────────────────────────────────────────────────────┤

│ │

│ ┌──────────────┐ HTTPS/TLS ┌───────────┐ │

│ │ ESP32 │◄────────────────────────────┤ Cloudflare│ │

│ │ (Client) │ Secure Tunnel │ CDN │ │

│ │ │ └─────┬─────┘ │

│ │ - Keypad │ │ │

│ │ - I2S Audio │ │ │

│ │ - FreeRTOS │ Encrypted Tunnel │ │

│ │ - Watchdog │ │ │

│ └──────────────┘ ┌─────┴─────┐ │

│ │Raspberry │ │

│ │ Pi │ │

│ │ │ │

│ │ - FastAPI │ │

│ │ - Markov │ │

│ │ - PyTorch │ │

│ └───────────┘ │

│ │

└─────────────────────────────────────────────────────────────┘

Component Breakdown

ESP32 (Client Side)

Hardware Interface: 4x4 Keypad input, I2S audio output

Processing: Dual-core FreeRTOS multi-threading

Communication: HTTPS over WiFi with TLS/SSL

Safety: Watchdog timer, mutex protection

Raspberry Pi (Server Side)

AI Engine: 4th-order Markov Chain with PyTorch

API: FastAPI RESTful web service

Storage: User session management, harmonic memory

Deployment: Systemd service auto-start

Cloud Infrastructure

CDN: Cloudflare global edge network

Security: SSL/TLS encryption, DDoS protection

Tunnel: Cloudflare Tunnel (no port forwarding needed)

DNS: Custom domain routing

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🎮 ESP32 Embedded System

1. Hardware Configuration

I2S Audio Output

#define BCLK_PIN 26 // Bit Clock

#define LRC_PIN 25 // Left/Right Clock (Word Select)

#define DIN_PIN 16 // Data In

#define SAMPLE_RATE 16000

#define BUFFER_SIZE 128

การทำงานของ I2S (Inter-IC Sound):

I2S คือ protocol สำหรับส่งสัญญาณเสียงดิจิทัลแบบ serial

Pin Configuration:

┌─────────────────────────────────────────┐

│ ESP32 → MAX98357A │

├─────────────────────────────────────────┤

│ GPIO 26 (BCLK) → BCLK (Bit Clock) │

│ GPIO 25 (LRC) → LRC (Word Select) │

│ GPIO 16 (DIN) → DIN (Data) │

│ GND → GND │

│ 5V/3.3V → VIN │

└─────────────────────────────────────────┘

Timing Diagram:

BCLK: _‾_‾_‾_‾_‾_‾_‾_‾_‾_‾_‾_‾_‾_‾_‾_‾

LRC: ___________‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾

DIN: [16-bit L][16-bit R][16-bit L]...

Sample Rate: 16000 Hz

Bit Depth: 16-bit

Channels: 2 (Left/Right)

Bitrate: 16000 × 16 × 2 = 512 kbps

I2S Configuration Code:

i2s_config_t i2s_config = {

.mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_TX),

// ↑ ESP32 เป็น master (สร้าง clock), TX = ส่งข้อมูล

.sample_rate = 16000,

// ↑ ส่ง sample 16000 ตัวต่อวินาที

.bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT,

// ↑ แต่ละ sample ใช้ 16 bits

.channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,

// ↑ สลับส่ง Left แล้ว Right

.communication_format = I2S_COMM_FORMAT_STAND_I2S,

// ↑ ใช้ standard I2S protocol

.intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,

// ↑ Interrupt priority level 1

.dma_buf_count = 8,

// ↑ ใช้ 8 DMA buffers

.dma_buf_len = 128,

// ↑ แต่ละ buffer เก็บได้ 128 samples

.use_apll = false,

// ↑ ไม่ใช้ APLL (Audio PLL) ใช้ clock ปกติ

.tx_desc_auto_clear = true

// ↑ ล้าง descriptor อัตโนมัติหลังส่งเสร็จ

};

DMA (Direct Memory Access) Explained:

DMA = การถ่ายโอนข้อมูลโดยไม่ผ่าน CPU

Without DMA:

CPU: Read data → Write to I2S → Repeat

↑ CPU blocked, can't do other work

With DMA:

CPU: Setup DMA → Do other work

DMA: Automatically transfer data to I2S

↑ CPU free to do other tasks!

Buffer Chain:

┌─────┐ ┌─────┐ ┌─────┐ ┌─────┐

│Buf 0│→│Buf 1│→│Buf 2│→│... │

└─────┘ └─────┘ └─────┘ └─────┘

↓ Sending ↑ CPU fills

Ping-Pong Buffering:

- DMA ส่ง buffer 0 → CPU เติม buffer 1

- DMA ส่ง buffer 1 → CPU เติม buffer 0

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4x4 Matrix Keypad

const byte ROWS = 4;

const byte COLS = 4;

char keys[ROWS][COLS] = {

{ '1', '2', '3', 'A' },

{ '4', '5', '6', 'B' },

{ '7', '8', '9', 'C' },

{ '*', '0', '#', 'D' }

};

byte rowPins[ROWS] = { 14, 27, 19, 18 }; // Output pins

byte colPins[COLS] = { 4, 13, 32, 33 }; // Input pins (pull-up)

Matrix Keypad Scanning:

Physical Connection:

Col0 Col1 Col2 Col3

↓ ↓ ↓ ↓

Row0 → [1] [2] [3] [A]

Row1 → [4] [5] [6] [B]

Row2 → [7] [8] [9] [C]

Row3 → [*] [0] [#] [D]

Scanning Algorithm:

1. Set all rows to HIGH

2. Set all columns to INPUT_PULLUP (HIGH)

3. For each row i:

- Set row[i] to LOW

- For each column j:

- If column[j] reads LOW:

→ Button at (i, j) is pressed!

- Set row[i] back to HIGH

Example: Press '5'

Row1 = LOW, Col1 = LOW detected

→ keys[1][1] = '5'

Debouncing:

- Library handles automatic debouncing

- Prevents multiple reads from single press

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2. Audio Generation

Sine Wave Synthesis

void generateAndPlayTone() {

unsigned long elapsed = millis() - noteStartTime;

float envelope = 1.0;

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