Reg: I2C frequency in MPC5675K

[ArunaNellaiappan]

We are using MPC5675K micro controller for communication interface with various sub systems of our project. It is mentioned in the User manual of MPC5675K(Chapter 31 in page 1136) that the I2C interface is designed to operate as fast as 100 kbps with maximum bus loading and timing. We are using 37.5 MHz frequency (Controller core frequency as 150 MHz) as the I2C_peripheral clock frequency.Our requirement is to operate the I2C bus interface with 400 KHz frequency. 1)What is the maximum speed of operation of I2C interface? 2)I2C Clock baud rate depends on I2C Multiplier factor and SCL divider(as per Table 31-4).What is the I2C Multiplier factor used for I2C clock and Hold values in Table 31-5?

[davidtosenovjan]

1) The I2C module is designed to meet the spec for Standard Mode as defined in original I2C specification from Philips/NXP:

http://www.nxp.com/documents/user_manual/UM10204.pdf

Data can be transferred on I2C bus at rates up to 100kbit/s in standard mode.

Prescaler in I2C module on MPC5675K allows us to set also higher speeds.

The speed is not limited to 100kbit/s. It depends just on your system clock and on prescaler. And it is also limited by capacitance of physical bus, of course.

With your setup it gives me theoretically up to 1.875MHz.

2) It does not matter, the specification is the same for all multiplier factors.