The model is not powered or the slave address is wrong. Fix: Ensure VCC=5V (or 3.3V) and GND are connected. Check if your firmware uses 0x68 (default) or 0x69 (if AD0 is high).
Debugging I2C communication in physical hardware requires oscilloscopes and logic analyzers. A Proteus model allows you to:
The model correctly handles clock stretching, making it compatible with both standard 100kHz and fast 400kHz I2C modes.