i want to connect DS 1307 serial RTC with microcontroller 8051. but i dont know which protocol i should use and how to select the protocol.... could anyone help me.
You should go for the I2C compatible RTC. Its easy to build with minimum resources. Just a battery, a clk source, and a micrcontroller.
For the I2C protocol, google it you will find lots of data. From them just study it basics, how to address the slave with read and write options. That's all required for this project.