I2C Overview:
- A 2-wire serial communication protocol (SDA for data, SCL for clock)
- Master-slave architecture, supporting multiple devices on the same bus
- Each slave device has a unique 7-bit or 10-bit address
- Typical speeds: 100kHz (Standard), 400kHz (Fast), 1MHz (Fast Plus), 3.4MHz (High Speed)
Key Things to Note:
- Hardware Considerations:
- Pull-up resistors are required on both SDA and SCL lines
- Bus capacitance affects maximum speed and pull-up resistor values
- Maximum bus length is limited by capacitance (typically few meters)
- Devices must share a common ground
- Addressing:
- Check for address conflicts between devices
- Some devices have configurable addresses via hardware pins
- Reserved addresses exist (e.g., general call address 0x00)
- Common Issues:
- Clock stretching by slow slaves can cause communication issues
- Bus contention if multiple masters aren’t properly managed
- Signal integrity problems at higher speeds or longer distances
- Noise sensitivity due to open-drain nature
- Best Practices:
- Keep wires short and away from noise sources
- Calculate proper pull-up resistor values based on:
- Bus capacitance
- Operating voltage
- Required speed
- Include scope for debugging (monitor both SDA and SCL)
- Consider bus buffers for longer distances or multiple segments
- Software Considerations:
- Implement proper timeout handling
- Check ACK/NACK responses
- Handle error conditions gracefully
- Consider clock stretching in time-critical applications
These points should help you avoid common pitfalls when implementing I2C communication in your projects.