ZEUS Technical Manual

Detailed hardware description

 

 

I²C bus

The PXA270 I²C interface is brought out to the COMs connector J19. See the section J19 – Serial ports – COM3/4, page 88, for connection details.

I²C bus is also used with the Quick Capture interface. See the section Quick Capture camera interface, page 59.

The following table lists the on-board I²C devices:

Device nameI²C address

External General Purpose I/O

0x20

On-board GPIO Expander 1

0x21

On-board GPIO Expander 2

0x22

Temperature Sensor (LM75A)

0x48

RTC (Intersil ISL1208)

0x6F

Config EPROM

0x50-0x57

 

 

The I²C unit supports a fast mode operation of 400KB/s and a standard mode of 100KB/s.

Fast-mode devices are downward compatible and can communicate with standard- mode devices in a 0 to 100KB/s I²C bus system. As standard-mode devices, however, are not upward compatible, they should not be incorporated in a fast-mode I²C bus system as they cannot follow the higher transfer rate and unpredictable states would occur.

The I²C interface does not support the hardware general call, 10-bit addressing, high-speed mode (3.4Mbit/s) or CBUS compatibility.

You should keep the total bus load below 200pF.

© 2007 Eurotech Ltd Issue D

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