VAR-320SBC Reference Guide
Copyright © 2008 Variscite
4.14. I2C
Bus
The PXA320 processor has two I2C peripherals: the standard I2C interface and the Power I2C
interface.
The standard I2C bus serves as the PXA320 processor interface to other I2C peripherals and
microcontrollers, as well as a method of managing system functions. The standard I2C bus allows
the PXA320 processor to serve as a master and slave device residing on the I2C bus. Control and
status information is relayed through a set of memory-mapped registers.
The Power I2C interface contains a subset of the standard I2C interface and is dedicated for
connection to an external voltage regulator for hard coded power management communication. If
PWR_EN or SYS_EN change state (for example during a power state change), the appropriate
I2C commands are transmitted to the PMIC as well. No configuration or software interaction is
required. The Power I2C interface cannot be used as a general- purpose I2C interface.
The
Power I2C is used internally by the VAR-320SBC and cannot be used by the user.
The standard I2C has a standard bus speed of 100 kbps and a fast-mode operation of 400 kbps.
*Both SDA and SCL lines are internally pulled up with a 1.2k resistor to 3.3v.
Signal
Pin number Type Description
SDA P1-60
I/O
Serial
data
for
the standard I2C controller.
SCL
P1-61
O
Serial clock for the standard I2C controller.
29