252 lines
6.2 KiB
Markdown
252 lines
6.2 KiB
Markdown
# RP2040-ETH Precision Timing Tool Development Instructions
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## Project Overview
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A precision timing tool using Waveshare RP2040-ETH with FreeRTOS for complex timing and scheduling operations.
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### Input Protocols
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- NTP (Network Time Protocol)
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- PTP (Precision Time Protocol)
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- IRIG (Inter-Range Instrumentation Group time codes)
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- GPS (Global Positioning System time)
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- PPS (Pulse Per Second)
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### Output Protocols
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- PTP (Precision Time Protocol)
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- NTP (Network Time Protocol)
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- IRIG-A (Audio frequency time code)
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## Development Environment Setup
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### Prerequisites
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1. **ARM GCC Toolchain**: arm-none-eabi-gcc
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2. **CMake**: Version 3.13 or higher
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3. **Pico SDK**: Will be included as submodule
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4. **FreeRTOS**: Will be included from RP2040-FreeRTOS repository
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5. **Python 3**: For build tools and utilities
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### Initial Setup Steps
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```bash
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# 1. Clone the FreeRTOS-RP2040 repository as reference
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git clone --recursive https://github.com/smittytone/RP2040-FreeRTOS.git reference/
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# 2. Set up Pico SDK environment variable
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export PICO_SDK_PATH=/path/to/pico-sdk
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# 3. Install required tools
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# macOS:
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brew install cmake python3 gcc-arm-embedded
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# Linux:
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sudo apt update
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sudo apt install cmake gcc-arm-none-eabi libnewlib-arm-none-eabi build-essential
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```
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## Project Architecture
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### Core Components
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1. **FreeRTOS Kernel Integration**
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- Task scheduling for time-critical operations
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- Inter-task communication via queues
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- Software timers for periodic updates
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- Interrupt handling for PPS and timing signals
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2. **Network Stack (CH9120)**
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- Ethernet controller management
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- TCP/UDP protocol implementation
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- NTP client/server functionality
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- PTP protocol stack
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3. **Timing Core**
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- High-precision time keeping
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- Clock synchronization algorithms
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- Time source arbitration
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- Drift compensation
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4. **Protocol Handlers**
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- NTP: RFC 5905 implementation
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- PTP: IEEE 1588 implementation
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- IRIG: Time code generation/decoding
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- GPS: NMEA/UBX parsing
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- PPS: Edge detection and timestamping
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### Task Structure
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```
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Main Tasks:
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├── Network Task (Priority: High)
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│ ├── Ethernet management
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│ ├── Protocol handling
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│ └── Packet processing
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├── Timing Task (Priority: Critical)
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│ ├── Clock maintenance
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│ ├── Synchronization
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│ └── Drift correction
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├── Input Task (Priority: High)
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│ ├── GPS parsing
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│ ├── PPS handling
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│ └── IRIG decoding
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├── Output Task (Priority: Normal)
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│ ├── NTP server
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│ ├── PTP master
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│ └── IRIG-A generation
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└── Management Task (Priority: Low)
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├── Configuration
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├── Monitoring
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└── Statistics
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```
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## Build Configuration
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### CMake Structure
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```cmake
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# Main CMakeLists.txt
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cmake_minimum_required(VERSION 3.13)
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include(pico_sdk_import.cmake)
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project(precision_timing_tool)
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pico_sdk_init()
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# Add FreeRTOS
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add_subdirectory(FreeRTOS-Kernel)
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# Project sources
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add_executable(timing_tool
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src/main.c
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src/network/ch9120.c
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src/network/ntp.c
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src/network/ptp.c
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src/timing/clock.c
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src/timing/sync.c
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src/io/gps.c
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src/io/pps.c
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src/io/irig.c
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)
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# Link libraries
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target_link_libraries(timing_tool
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pico_stdlib
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hardware_spi
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hardware_i2c
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hardware_dma
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hardware_pio
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hardware_timer
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FreeRTOS
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)
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```
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## Hardware Connections
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### Pin Assignments
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```
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CH9120 Ethernet Controller:
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- UART1 TX: GPIO 20
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- UART1 RX: GPIO 21
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- CFG: GPIO 18
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- RES: GPIO 19
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GPS Module:
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- UART0 TX: GPIO 0
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- UART0 RX: GPIO 1
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- PPS: GPIO 2 (interrupt)
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IRIG Interface:
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- Input: GPIO 3 (capture)
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- Output: GPIO 4 (PWM)
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Status LEDs:
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- System: GPIO 25
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- GPS Lock: GPIO 26
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- Network: GPIO 27
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- PTP Sync: GPIO 28
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```
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## Development Workflow
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1. **Initial Development**
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- Set up basic FreeRTOS tasks
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- Implement CH9120 driver
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- Create timing core structure
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2. **Protocol Implementation**
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- Start with NTP client
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- Add GPS time source
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- Implement PPS interrupt handler
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- Add NTP server functionality
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3. **Advanced Features**
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- PTP implementation
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- IRIG encoding/decoding
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- Clock discipline algorithms
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- Web configuration interface
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4. **Testing & Validation**
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- Unit tests for protocol handlers
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- Integration tests with reference clocks
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- Long-term stability testing
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- Network stress testing
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## Configuration
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### FreeRTOSConfig.h Key Settings
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```c
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#define configUSE_PREEMPTION 1
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#define configUSE_PORT_OPTIMISED_TASK_SELECTION 0
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#define configUSE_TICKLESS_IDLE 0
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#define configCPU_CLOCK_HZ 133000000
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#define configTICK_RATE_HZ 1000
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#define configMAX_PRIORITIES 32
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#define configMINIMAL_STACK_SIZE 256
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#define configTOTAL_HEAP_SIZE (128 * 1024)
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#define configUSE_MUTEXES 1
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#define configUSE_RECURSIVE_MUTEXES 1
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#define configUSE_COUNTING_SEMAPHORES 1
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#define configQUEUE_REGISTRY_SIZE 8
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#define configUSE_QUEUE_SETS 1
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#define configUSE_TIME_SLICING 1
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```
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## Debugging
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### Debug Output
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- UART0: GPS data (when not connected)
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- USB Serial: Debug console
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- SWD: Hardware debugging
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### Performance Monitoring
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- FreeRTOS task statistics
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- Network packet counters
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- Time synchronization metrics
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- Clock drift measurements
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## Next Steps
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1. Create project structure based on FreeRTOS template
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2. Implement basic CH9120 communication
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3. Add GPS NMEA parser
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4. Implement NTP client
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5. Add PPS interrupt handler
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6. Create basic web interface
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7. Implement additional protocols
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## Innovative Ideas
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1. **Multi-source Time Fusion**
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- Kalman filter for optimal time estimation
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- Automatic source quality assessment
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- Seamless failover between sources
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2. **Adaptive Network Timing**
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- Machine learning for network delay prediction
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- Dynamic packet rate adjustment
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- Congestion-aware protocol selection
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3. **Hardware Timestamping**
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- PIO state machines for precise capture
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- DMA-based packet timestamping
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- Sub-microsecond accuracy
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4. **Configuration Options**
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- Web-based management interface
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- SNMP monitoring
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- REST API for integration
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- Mobile app for configuration |