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SMBus SLAVE DRIVER FOR ST7 I2C PERIPHERAL

Figure 1. Data transfer format

SMBDAT: SMBus data line

SMBCLK: SMBus clock line

2.2 Differences between SMBus and I2C

The following table describes the differences between SMBus and I2C.

Table 1. SMBus vs I2C

2.3 SMBus Application

With System Management Bus, a device can provide manufacturer information, tell the

system what its model/part number is, save its state for a suspend event, report different types

of errors, accept control parameters, and return its status. SMBus provides a control bus for

system and power management related tasks.

SMBus

ST7 I2C

Max. speed 100 kHz

Max. speed 400 kHz

Min. clock speed 10 kHz

No minimum clock speed

35ms clock low time-out

No time-out

Logic levels are fixed

Logic levels are VDD dependent

Different address types (reserved, dynamic

etc.)

7-bit, 10-bit and general call slave address

types

Different bus protocols (quick command, proc-

ess call etc.)

No bus protocols

Packet error checking (PEC) implemented

No packet error checking. Only error status

indication

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