CP3UB26G18NEPX National Semiconductor, CP3UB26G18NEPX Datasheet - Page 69

• Manufacturer Part Number: CP3UB26G18NEPX
• Manufacturer: National Semiconductor

Specifications of CP3UB26G18NEPX

• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 128
• Package Type: LQFP
• Lead Free Status / RoHS Status: Not Compliant

14.0 Input/Output Ports
Each device has up to 54 software-configurable I/O pins, or-
ganized into 8-bit ports (not all bits are used in some ports).
The ports are named Port B, Port C, Port E, Port F, Port G,
Port H, and Port J.
In addition to their general-purpose I/O capability, the I/O
pins of Ports E, F, G, H, and J have alternate functions for
use with on-chip peripheral modules such as the UART or
the Multi-Input Wake-Up unit. The alternate functions of all
I/O pins are shown in Table 91.
Ports B and C are used as the 16-bit data bus when an ex-
ternal bus is enabled (144-pin devices only). This alternate
function is selected by enabling the DEV or ERE operating
environments, not by programming the port registers.
The I/O pin characteristics are fully programmable. Each pin
can be configured to operate as a TRI-STATE output, push-
pull output, weak pull-up input, or high-impedance input.
14.1
Each port has an associated set of memory-mapped regis-
ters used for controlling the port and for holding the port da-
ta:
PORT REGISTERS
Figure 13. I/O Port Pin Logic
69
Different pins within the same port can be individually con-
figured to operate in different modes.
Figure 13 is a diagram showing the I/O port pin logic. The
register bits, multiplexers, and buffers allow the port pin to
be configured into the various operating modes. The output
buffer is a TRI-STATE buffer with weak pull-up capability.
The weak pull-up, if used, prevents the port pin from going
to an undefined state when it operates as an input.
To reduce power consumption, input buffers configured for
general-purpose I/O are only enabled when they are read.
When configured for an alternate function, the input buffers
are enabled continuously. To minimize power consumption,
input signals to enabled buffers must be held within 0.2 volts
of the VCC or GND voltage.
The electrical characteristics and drive capabilities of the in-
put and output buffers are described in Section 29.0.
! PxALT: Port alternate function register
! PxALTS: Port alternate function select register
! PxDIR: Port direction register
! PxDIN: Port data input register
! PxDOUT: Port data output register
! PxWPU: Port weak pull-up register
! PxHDRV: Port high drive strength register
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