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Features Overview

SerialyTTY combines multiple advanced features into a comprehensive serial communication tool.

Core Features​

🎯 Intelligent Baud Rate Detection​

Automatically detects the communication speed of connected devices without manual configuration.

How it works:

  • GPIO interrupt-based bit timing measurement
  • Analyzes falling edge patterns on RX line
  • Calculates bit period from timing samples
  • Supports standard baud rates: 9600, 19200, 38400, 57600, 115200

Use cases:

  • Unknown device interrogation
  • Automatic configuration
  • Multi-device testing
  • Educational demonstrations

Technical details:

  • Precision: ±2% tolerance
  • Detection time: <1 second (typical)
  • Minimum data: 8 bytes required
  • Interrupt latency: <10µs

🔄 Transparent Bridge Mode​

Bidirectional serial data passthrough between USB and UART.

Features:

  • Zero-latency forwarding (interrupt-driven)
  • Real-time RX/TX byte counters
  • Escape sequence (~~~) for mode exit
  • Buffer management (1KB TX/RX)

Performance:

  • Throughput: Up to 115200 bps
  • Latency: <1ms typical
  • Buffer overflow protection
  • Error detection and logging

Use cases:

  • Device programming
  • Debugging embedded systems
  • Protocol analysis
  • Firmware updates

📺 TFT Display Integration​

240x320 color display for visual feedback and status monitoring.

Display Screens:

  1. Boot Screen

    • SerialyTTY logo
    • Firmware version
    • Hardware detection status
    • Initialization progress

  2. Menu Screen

    • Command list (D, B, S, I, H)
    • Hardware status indicators
    • Navigation instructions
    • Current state display

  3. Analyzing Screen

    • Baud detection progress
    • Real-time bit timing
    • Instruction prompts
    • Detection status

  4. Bridge Screen

    • Live RX/TX counters
    • Current baud rate
    • Connection status
    • Escape sequence hint

Technical Features:

  • DMA-accelerated rendering
  • 8x8 bitmap font (custom)
  • RGB565 color depth
  • 40 MHz SPI clock
  • 30+ FPS update rate
  • Multi-line text support

💾 SD Card Logging​

Comprehensive logging system with timestamped entries and structured data.

Log Structure:

[2025-12-08 14:32:15] [INFO] System boot complete
[2025-12-08 14:32:20] [BAUD] Detected: 115200 bps
[2025-12-08 14:32:25] [DATA] TX: 48 65 6C 6C 6F 20 57 6F 72 6C 64
[2025-12-08 14:32:30] [STATE] Entering bridge mode

Log Levels:

  • INFO - System events and status changes
  • DATA - Communication data (hex dump)
  • BAUD - Baud rate detection results
  • STATE - State machine transitions
  • TEST - Testing and diagnostic data
  • ERROR - Error conditions

Features:

  • Auto-flush every 10 entries
  • Binary data hex encoding
  • Large packet handling (up to 128 bytes shown)
  • Timestamped filenames: log_YYYYMMDD_HHMMSS.txt
  • Directory auto-creation: /sdcard/logs/

Storage:

  • FAT16/FAT32 filesystem
  • Up to 32GB cards supported
  • VFS (Virtual Filesystem) integration
  • Safe unmount on shutdown

🖥️ Interactive Menu System​

Professional ANSI-formatted terminal interface for device control.

Commands:

KeyCommandDescription
DDetect BaudStart automatic baud rate detection
BBridge ModeEnter transparent passthrough mode
SSettingsConfigure device parameters (future)
IInfoDisplay hardware and system information
HHelpShow command reference

Menu Features:

  • ANSI color coding
  • Clear screen control
  • Keyboard navigation
  • State-aware prompts
  • Context-sensitive help

System States:

  • BOOTING - Initialization in progress
  • MENU - Main menu active
  • ANALYZING - Baud detection running
  • FOUND_SPEED - Baud rate detected
  • BRIDGE - Passthrough mode active
  • TESTING - Communication test mode

🔍 Hardware Auto-Detection​

Intelligent scanning and configuration of connected peripherals.

Detection Methods:

  1. I2C Scan

    • Probes address range 0x08-0x77
    • Identifies display controllers
    • Detects sensors and expanders
    • Reports found devices

  2. GPIO Detection

    • Tests chip select (CS) lines
    • Verifies SPI peripheral presence
    • Validates pin states
    • Checks pull-up/pull-down

  3. SPI Probe

    • Attempts device initialization
    • Reads manufacturer IDs
    • Verifies communication
    • Reports capabilities

Graceful Degradation:

  • Continues operation without peripherals
  • Adapts feature set to available hardware
  • Clean boot with missing devices
  • No blocking or errors

📡 Bluetooth LE Support (Stub)​

Framework ready for Nordic UART Service (NUS) implementation.

Planned Features:

  • Wireless serial bridging
  • Mobile app connectivity
  • Over-the-air configuration
  • Remote monitoring

Current Status:

  • BLE stack initialized
  • Service UUID defined
  • Characteristic handlers ready
  • Requires implementation completion

Advanced Capabilities​

State Management​

Robust state machine with clean transitions:

BOOTING → MENU → ANALYZING → FOUND_SPEED → BRIDGE
   ↑         ↓                                  ↓
   └─────────┴──────────────────────────────────┘

Features:

  • Atomic state transitions
  • Callback-based event handling
  • State history tracking
  • Timeout management

Error Handling​

Comprehensive error detection and recovery:

  • UART framing errors
  • SPI communication failures
  • SD card write errors
  • Buffer overflow protection
  • Watchdog timer (future)

Performance Optimization​

DMA (Direct Memory Access):

  • Display buffer transfers
  • UART TX/RX operations
  • Reduced CPU overhead
  • Higher throughput

Interrupt-Driven I/O:

  • Sub-microsecond response
  • Precise timing measurements
  • Non-blocking operations
  • Priority-based handling

FreeRTOS Integration:

  • Task-based architecture
  • Efficient scheduling
  • Resource sharing
  • Synchronization primitives

Integration Features​

SPI Bus Sharing​

Efficient sharing between TFT and SD card:

  • Mutex-based arbitration
  • Separate chip select (CS) management
  • Different clock speeds per device
  • Error state handling (ESP_ERR_INVALID_STATE)

Dual UART Configuration​

  • UART0: USB serial (console, menu, logging)
  • UART1: Target device (bridge, detection)
  • Independent baud rates
  • Isolated buffers
  • Cross-communication support

Timestamping​

  • RTC integration
  • Microsecond precision
  • ISO 8601 format
  • Timezone support (configurable)

Future Features (Roadmap)​

Phase 5 - Protocol Analysis​

  • I2C bus analyzer
  • SPI protocol decoder
  • Modbus RTU support
  • Custom protocol parsers

Phase 6 - Data Visualization​

  • Real-time waveform display
  • Protocol timeline view
  • Statistics graphs
  • Packet inspection

Phase 7 - Advanced Logging​

  • Circular buffer recording
  • Trigger-based capture
  • Data replay functionality
  • Export to CSV/JSON

Phase 8 - Connectivity​

  • WiFi web interface
  • BLE UART service
  • MQTT data publishing
  • REST API

Feature Comparison​

FeatureSerialyTTYBasic USB-TTLLogic Analyzer
UART Bridge✅✅❌
Auto Baud✅❌❌
Display✅❌✅ (PC)
SD Logging✅❌✅
Live Stats✅❌✅
Standalone✅✅❌
Protocol Decode🔄❌✅
Triggering🔄❌✅
Cost~$15~$5$50-500

Legend: ✅ Supported | ❌ Not supported | 🔄 Planned

Next: Dive into the Software Architecture to understand how it all works.