# TurboCobalt

> **High-Performance Desktop Multi-Tool for Software Developers**

📘 **Project Specifications**

**Version:** 1.0  
**Core System:** STM32G491 (Arm Cortex-M4F @ 170MHz)  
**Operating System:** FreeRTOS  
**Development Status:** Design Phase  
**Target Market:** Professional Software Development Tools

## Table of Contents

- [1. Concept Overview](#1-concept-overview)
- [2. System Architecture](#2-system-architecture)
- [3. Component Selection & Rationale](#3-component-selection--rationale)
- [4. Bill of Materials (BOM)](#4-bill-of-materials-bom)
- [5. Hardware Architecture](#5-hardware-architecture)
- [6. Software Architecture (FreeRTOS Tasks)](#6-software-architecture-freertos-tasks)
- [7. Operational Modes](#7-operational-modes)
- [8. System Data Flow Summary](#8-system-data-flow-summary)
- [9. Technical Specifications](#9-technical-specifications)

---

## 💡 1. Concept Overview

TurboCobalt is a high-end desktop multi-tool designed for software developers. It merges retro-analog aesthetics with modern digital power to provide:

- **Analog Monitoring:** PC resource tracking (CPU/RAM) via physical galvanometers
- **Audio Synthesis:** 2 channel sound engine via I2S protocol
- **Interactive Interface:** Graphical LCD and rotary encoder for system navigation
- **Industrial Gateway:** USB bridge to fieldbus protocols (CAN-FD, Modbus/RS485)

### Key Design Principles

- **Real-Time Performance:** FreeRTOS ensures deterministic response times
- **Professional Grade:** Industrial-standard communication protocols
- **Developer Focused:** Productivity tools integrated into hardware
- **Extensible Architecture:** Modular design for future enhancements

---

## 🏗️ 2. System Architecture

```mermaid
graph TB
    PC[PC/Host Computer] --> USB[USB-C]
    USB --> MCU[STM32G491<br/>ARM Cortex-M4F]
    
    subgraph MEM ["Memory Subsystem"]
        EEPROM[24LC512<br/>64KB EEPROM]
        PSRAM[APS1604M<br/>16MB PSRAM]
        RTC[DS3231<br/>RTC + Battery]
    end
    
    subgraph ANALOG ["Analog Monitoring"]
        PWM1[PWM + Filter] --> GAL1[CPU Meter<br/>SO-45]
        PWM2[PWM + Filter] --> GAL2[RAM Meter<br/>SO-45]
    end
    
    subgraph AUDIO ["Audio Chain"]
        I2S[I2S Interface] --> DAC[PCM5102<br/>Audio DAC] --> OUT[🎵 Audio Out]
    end
    
    subgraph UI ["User Interface"]
        LCD[128x64 Display<br/>NHD-C12864LZ]
        ENC[Rotary Encoder<br/>+ Button]
    end
    
    subgraph FIELDBUS ["Industrial I/O"]
        CAN_TX[TJA1050] --> CAN_BUS[CAN-FD Bus]
        RS485_TX[MAX485] --> MODBUS[Modbus RS485]
    end
    
    subgraph PWR ["Power"]
        POWER[USB 5V] --> LDO[3.3V Regulator]
    end
    
    MCU -.-> MEM
    MCU --> ANALOG
    MCU --> AUDIO
    MCU --> UI
    MCU --> FIELDBUS
    LDO --> MCU
```

---

## 🔧 3. Component Selection & Rationale

### Primary MCU: STM32G491

**Selection Criteria Met:**
- **Performance:** 170MHz ARM Cortex-M4F with DSP instructions
- **Audio Processing:** Hardware CORDIC accelerator for real-time synthesis
- **Connectivity:** Integrated CAN-FD controller eliminates external chips
- **Memory:** 128KB SRAM sufficient for FreeRTOS + audio buffers
- **Package:** LQFP-80 provides adequate I/O for all peripherals

**Key Advantages:**
- Mathematical accelerator reduces CPU load for audio algorithms
- Advanced timer units enable precise PWM generation for galvanometers
- Fast ADC enables potential future analog input expansion

### Memory Subsystem

| Component | Part Number | Capacity | Interface | Purpose | Rationale |
|-----------|-------------|----------|-----------|----------|-----------|
| EEPROM | 24LC512 | 64KB | I2C | Config Storage | Non-volatile, reliable for settings |
| PSRAM | APS1604M | 16MB | SPI/QPI | Audio Buffer & Samples | Premium capacity, 144MHz, future-proof |

### 📊 **PSRAM Capacity Analysis**

**Calculated Requirements:**
- **Audio Buffers (48kHz, 24-bit, 2ch):** ~200KB (multiple buffers + safety margin)  
- **Sample Storage:** ~10-15MB (extensive soundbanks, high-quality samples, user recordings)  
- **Communication Buffers:** ~50KB (USB, CAN-FD, Modbus queues)  
- **UI Graphics Buffer:** ~50KB (advanced display cache, animations, menus)  
- **System Overhead:** ~200KB (FreeRTOS heap extension)  

**APS1604M 16MB PSRAM**
- **Studio-Grade Capacity:** 1000+ high-quality samples (24-bit, 48kHz)
- **Multi-Project Storage:** Multiple soundbanks and user configurations
- **Advanced Features:** Real-time convolution, complex synthesis algorithms  
- **Recording Capability:** Store user recordings directly to PSRAM
- **Performance:** 144MHz clock - fastest available option
- **Future-Proof:** Extensive room for firmware expansion

### Audio Chain

**DAC Selection: PCM5102**
- 24-bit resolution, 192kHz sampling rate
- I2S interface directly compatible with STM32
- Low THD+N: 0.0008% typical
- Self-clocking eliminates need for external crystal

### Analog Indicators

**Galvanometer Choice: SO-45 Series**
- Vintage aesthetic with modern reliability
- Fast response time (<200ms full scale)
- Linear voltage-to-deflection characteristics
- Standard 0-5V input range matches PWM filtering

---

## 🛠️ 4. Bill of Materials (BOM)

### Core Components

| Category | Component | Part Number | Specs | Rationale |
|----------|-----------|-------------|-------|------------|
| **MCU** | Microcontroller | STM32G491RET6 | 170MHz ARM-M4F, 512KB Flash | CORDIC accelerator + CAN-FD integrated |
| **Memory** | PSRAM | APS1604M-3SQR | 16MB, 144MHz SPI/QPI | Premium audio capacity + performance |
| **Memory** | EEPROM | 24LC512-I/P | 64KB I2C | Non-volatile config storage |
| **RTC** | Real-Time Clock | DS3231SN | ±2ppm, I2C, Battery backup | Precision timekeeping |
| **Audio** | DAC | PCM5102A | 24-bit, 192kHz I2S | Studio-grade audio quality |
| **Display** | LCD | NHD-C12864LZ | 128x64, SPI | Professional readability |
| **Analog** | Galvanometer (x2) | SO-45 | 0-5V, <200ms response | Vintage aesthetic + reliability |
| **CAN** | Transceiver | TJA1050T | CAN-FD compatible | Industrial fieldbus standard |
| **RS485** | Transceiver | MAX485CSA | Full-duplex RS485 | Modbus communication |

### Technology Choices Summary

**🎯 Key Design Decisions:**
- **STM32G491:** Best-in-class for audio (CORDIC) + industrial connectivity (CAN-FD)
- **16MB PSRAM:** Premium capacity enabling studio-grade sample storage
- **PCM5102:** Professional DAC with excellent THD+N performance  
- **SO-45 Galvanometers:** Authentic retro aesthetic with modern reliability
- **I2S Audio Chain:** Eliminates noise, ensures digital precision to DAC
- **SPI/QPI Memory:** High-speed access for real-time audio processing

---

## ⚡ 5. Hardware Architecture

### 🖥️ Processing & Memory

- **MCU:** STM32G491 (High-performance, CORDIC math accelerator for audio, integrated FDCAN)
- **EEPROM (I2C):** 24LC512 (64 KB) for presets, logs, and persistent configuration storage
- **PSRAM (SPI/QPI):** APS1604M (16MB) for extensive audio sample storage and real-time processing
- **RTC:** DS3231 for precise alarm and clock functions

### 🔌 Connectivity & I/O

- **USB:** Main USB-C interface supporting Composite Device Classes: CDC (Data) and HID (Keyboard/Control)
- **Audio:** I2S bus connected to an external DAC (e.g., PCM5102)
- **Display:** Newhaven NHD-C12864LZ (128x64 pixels) via high-speed SPI
- **Indicators:** 2x SO-45 Galvanometers driven by filtered PWM (Pulse Width Modulation) outputs

### Fieldbus Ports

- **CAN-FD Port:** Dedicated connector via TJA1050 (or equivalent) transceiver
- **RS485/Modbus Port:** Dedicated connector via MAX485 (or equivalent) transceiver

---

## 💻 6. Software Architecture (FreeRTOS Tasks)

The FreeRTOS implementation ensures low-latency audio processing and responsive UI handling by isolating critical tasks.

| Task Name | Priority | Description |
|-----------|----------|-------------|
| Task_Audio | 1 (Critical) | Signal synthesis and I2S DMA buffer management |
| Task_USB_Comm | 2 (High) | USB stack management, receiving PC stats and HID commands |
| Task_Gateway | 3 (Medium) | Packet routing between USB and CAN/Modbus interfaces |
| Task_UI | 4 (Medium) | NHD display refresh and rotary encoder debouncing/logic |
| Task_Sensors | 5 (Low) | Periodic RTC, Temperature, and EEPROM housekeeping |

---

## ⚙️ 7. Operational Modes

- **Studio Mode:** Operates as a standalone synthesizer or MIDI controller
- **Monitor Mode:** Visualizes real-time dev-machine performance (CPU/RAM load)
- **Gateway Mode:** Acts as a transparent bridge between the PC and industrial buses (CAN/Modbus)
- **Dev-Tool Mode:** Physical password vault (HID injection) and Pomodoro productivity timer

---

## 🔄 8. System Data Flow Summary

### Primary Data Paths

- **PC → USB:** Streams CPU/RAM utilization data to the MCU
- **STM32 → PWM:** Maps data to voltage levels to move the SO-45 needles
- **STM32 → I2S:** Outputs real-time generated waveforms to the audio DAC
- **External Bus ↔ STM32 ↔ USB:** Bi-directional data transit for CAN/Modbus debugging

### Performance Metrics

- **USB Latency:** <1ms for HID commands
- **Audio Latency:** <5ms buffer (configurable)
- **Galvanometer Update Rate:** 60Hz
- **Display Refresh Rate:** 30Hz
- **CAN/Modbus Throughput:** Up to 1Mbps (CAN-FD), 115.2kbps (RS485)

---

## 📋 9. Technical Specifications

### Power Requirements

- **Input:** USB-C 5V, 500mA maximum
- **Consumption:** 
  - Idle: ~150mA @ 5V
  - Active Audio: ~300mA @ 5V
  - Peak (All peripherals): ~450mA @ 5V

### Environmental Specifications

- **Operating Temperature:** 0°C to +70°C
- **Storage Temperature:** -40°C to +85°C
- **Humidity:** 10-90% RH, non-condensing
- **Dimensions:** TBD (Desktop form factor)

### Compliance & Standards

- **USB:** USB 2.0 Full Speed compliant
- **CAN:** ISO 11898-1 (CAN-FD)
- **RS485:** TIA/EIA-485-A
- **EMC:** Designed for CE marking compliance
- **Safety:** Low voltage, USB powered design

### Development Tools

- **RTOS:** FreeRTOS v10.x
- **HAL:** STM32 HAL Driver
- **Debug:** SWD interface with ST-Link
- **Version Control:** Git-based workflow