14.2.4.3 SMBus and PMBus Overview
The SMBus is a two-wire interface through which devices can communicate with each other. The SMBus interface can operate as a master or a slave. It is derived from the principles of operation of I2C. See SMBus protocol v2.0 specification for more information.
Power management bus (PMBus) is an open standard two-wire communications protocol through which devices can communicate with each other. See PMBus protocol v1.1 specification for more information.
The following figure shows a PMBus or SMBus device interface example using the Cortex-M3 processor, I2C, MSS, and general purpose input/output (GPIO).
PMBus protocols are run through the serial bus, and the additional PMBus control signal is routed through MSS GPIO. External SMBus devices may also be connected to the same bus, as shown in the figure.
For an SMBus application, it is advised to choose a PCLK so that the SCL transfers data at near the maximum frequency to ensure that other potential clock-stretching devices on the bus do not slow the clock frequency to below the minimum allowed SMBus clock frequency.
