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Hardware Communication Protocols - Technical Guide

Protocol Comparison Matrix

Feature I2C UART TCP/IP
Physical Layer 2-wire (SDA, SCL) 2-wire (TX, RX) Ethernet
Max Distance ~1-2 meters ~15 meters Network unlimited
Max Speed 400 kHz (Fast mode) 115200 baud typical 10/100 Mbps
Addressing 7-bit device address Point-to-point IP + Port
Error Detection ACK/NACK Parity bit TCP checksums
Complexity Medium Low High
Power Usage Low Low Medium-High
Cost Low Low Medium

Communication Flow Diagrams

I2C Communication Flow

Master                           Slave
  |                                |
  |-------- START condition ----->|
  |------ Device Address + W ---->| ACK
  |-------- Command/Data -------->| ACK
  |-------- STOP condition ------>|
  |                                |
  |-------- START condition ----->|
  |------ Device Address + R ---->| ACK
  |<------- Response Data --------| 
  |-------- STOP condition ------>|

UART Communication Flow

Master (TX)                  Slave (RX)
    |                           |
    |-- Start Frame (0xABCD) -->|
    |-- Command ID ----------->|
    |-- Data Fields ---------->|
    |-- Checksum ------------->|
    |                           |
    |                           |-- Validation
    |                           |-- Command Processing
    |                           |-- Response (optional)

TCP/IP Communication Flow

Client                      Server (Arduino)
  |                              |
  |-- TCP SYN ------------------>|
  |<- TCP SYN-ACK --------------- |
  |-- TCP ACK ------------------>|
  |                              |
  |-- Application Data --------->|
  |<- Application Response ------|
  |                              |
  |-- TCP FIN ------------------>|
  |<- TCP FIN-ACK --------------- |

Data Encoding Methods

I2C Bytewise Encoding

  • Original: 10-bit ADC (0-1023)
  • Transmission: 8-bit (0-255)
  • Conversion: value >> 2 (divide by 4)
  • Recovery: received_value << 2 (multiply by 4)

I2C Byteshift Encoding

  • Original: 16-bit integer
  • Transmission: 2 × 8-bit bytes
  • Split: union byteint { byte b[2]; int i; }
  • Recovery: result = byte1 + (byte2 * 256)

UART Structured Encoding

Packet Structure (22 bytes):
+--------+----+------+-------+-------+----------+
| Start  | ID | Data | Data1 | Data2 | Checksum |
| 2 bytes| 2  |  2   |   2   |   2   |    2     |
+--------+----+------+-------+-------+----------+

TCP/IP Binary Encoding

  • Same structure as UART
  • Transmitted over TCP socket
  • Network byte order considerations
  • Endianness handling required

Error Handling Strategies

I2C Error Handling

  1. Bus Errors: SCL/SDA line monitoring
  2. Address Errors: NACK detection on address
  3. Data Errors: NACK detection on data
  4. Timeout Errors: Clock stretching limits

UART Error Handling

  1. Frame Errors: Start frame validation
  2. Checksum Errors: Data integrity verification
  3. Buffer Overflow: Index bounds checking
  4. Timeout Errors: Character reception timing

TCP/IP Error Handling

  1. Connection Errors: Socket status monitoring
  2. Network Errors: Link status checking
  3. Data Errors: Application-level validation
  4. Timeout Errors: Socket timeout configuration

Performance Optimization Tips

I2C Optimization

  • Use clock stretching appropriately
  • Minimize transaction overhead
  • Batch multiple operations
  • Consider I2C bus capacitance

UART Optimization

  • Choose optimal baud rates
  • Implement flow control if needed
  • Use DMA for high-speed transfers
  • Buffer management for continuous data

TCP/IP Optimization

  • Use persistent connections
  • Implement connection pooling
  • Consider UDP for real-time data
  • Optimize packet sizes

Troubleshooting Guide

Common I2C Issues

  • No ACK: Check wiring, pull-up resistors
  • Bus lockup: Implement bus recovery procedure
  • Data corruption: Check for electrical interference
  • Slow performance: Verify clock speed settings

Common UART Issues

  • No data: Check baud rate, wiring
  • Corrupted data: Verify parity settings
  • Buffer overflow: Increase buffer size or read faster
  • Timing issues: Check crystal accuracy

Common TCP/IP Issues

  • No connection: Check IP configuration, cables
  • Slow performance: Check network congestion
  • Connection drops: Implement keep-alive
  • Data loss: Use TCP acknowledgments

Circuit Design Considerations

I2C Circuit Requirements

  • Pull-up resistors: 4.7kΩ typical
  • Short traces for high-speed operation
  • Common ground reference
  • Proper power supply decoupling

UART Circuit Requirements

  • Direct connection or RS-232 level shifters
  • Twisted pair cables for long distances
  • Ground isolation for noisy environments
  • Flow control signals if required

TCP/IP Circuit Requirements

  • Ethernet magnetic isolation
  • Power-over-Ethernet considerations
  • EMI shielding for high-speed signals
  • Proper grounding techniques

This technical guide provides detailed implementation guidance for all three communication protocols implemented in this repository.