vsc055xkm-01 Maxim Integrated Products, Inc., vsc055xkm-01 Datasheet - Page 25

• Manufacturer Part Number: vsc055xkm-01
• Description: Enhanced I?c Backplane Controller
• Manufacturer: Maxim Integrated Products, Inc.

VSC055-01
Data Sheet
3.2.8
3.2.9
07h: General-Purpose I/O Port 7 Data (GPD7)
The following table shows the bit assignments for the General-Purpose I/O Port 7 Data register.
10h: I/O Port 0 Data Direction (DDP0)
The following table shows the bit assignments for the I/O Port 0 Data Direction register.
Register Name:
Address:
Reset Value:
Bit
7:0
Register Name:
Address:
Reset Value:
Bit
7:0
Bit Label
GPD7.7-0
Bit Label
DDP0.7-0
GPD7
07h
XXXX_XXXXb
DDP0
10h
1111_1111b
Access
R/W
Access Description
R/W
General-Purpose Data
When the I/O pin is enabled as an output, writing these bits determines the data
value that will be present on the corresponding I/O pin.
If the I/O pin is enabled as an input, reading these register bits represents the
current voltage applied to the pin. At no time do the bits directly represent the
value latched into the data register.
If a pin is enabled as an input and there is no signal applied, weak internal pull-
up resistors hold the pin at a binary 1.
After a reset or power on, the register bits are set to a binary 1, however, the
value returned from a register read is the level applied to the pin since each pin
is an input by default.
Description
Data Direction
These bits determine the direction of the data flow through the I/O pin.
To enable the respective I/O pin as an input, set the appropriate bit.
To enable the respective I/O pin as an output, reset the appropriate bit.
Each I/O pin can be individually configured as a true bidirectional function. To
implement an open-drain or open-source function, set or reset the appropriate
data bit using the data direction bit as the programmed data value.
After a reset or power on, these bits are set to a binary 1, enabling the I/O as an
input with weak pull-up.
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January 2008
Revision 4.1