Hello

I have questions regarding i2c bus communication

For example If PIC microcontroller running at 20 Mhz and Slave device running at 32.768 KHz

What would be speed of i2c bus ?

Thanks a lot

 

The I2C clock, which is generated by the master, is commonly 100kHz or 400kHz but could be anything less than some maximum value limited by the capabilities of the master and slave and also by the value of the pull-up resistors and the cable length.

 

The I2C bus clock rate is not directly related to the main clock of the devices on the bus. The designer must determine the bus clock rate based on the maximum rate supported by each device on the bus and the characteristics of the interconnection (value of pull-up resistors, stray capacitance, etc.). Then, set the bus clock rate on any master on the bus producing the bus clock. The specification defines "modes" which have a maximum bus clock rate but these are only maximums. In the end, the designer selects the clock rate.

 

The I2C clock, which is generated by the master, is commonly 100kHz or 400kHz but could be anything less than some maximum value limited by the capabilities of the master and slave and also by the value of the pull-up resistors and the cable length.

Take a look at this board https://www.amazon.in/Silicon-Techn...ocphy=9040229&hvtargid=pla-406302713025&psc=1

For example lets assume there is microcontroller P89V51Rd2 running at 11.0592MHz and Ds1307

Could you explain What would be the speed of i2c bus ?

 

Looking at the DS1307 the clock frequency can be anything up to 100kHz. If the designer wanted, the clock could be a lot slower but cannot be faster than that.

 

Looking at the DS1307 the clock frequency can be anything up to 100kHz. If the designer wanted, the clock could be a lot slower but cannot be faster than that.
View attachment 193639

Thank you AlbertHall so I2c bus can be send/ receive data at the maximum speed of about 100 kbis/s for ds1307?

the cable length.

What is meaning of cable length ?

 

Thank you AlbertHall so I2c bus can be send/ receive data at the maximum speed of about 100 kbis/s for ds1307?


What is meaning of cable length ?

The length of wire between the master and the slave. Longer wire means more capacitance and inductance to mess with the signals. Over longer wires you might use lower value pull up resistors and maybe a slower clock speed.

 

The length of wire between the master and the slave.

How long I can place ds1307 from microcontroller ?

 

There is no one answer to that either.
Read here: https://electronics.stackexchange.com/questions/106265/maximum-i2c-bus-length