CP3SP33SMSSLASHNOPB datasheet(109/407 Pages) TI1

109 / 407 page

CP3SP33

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SNOSCW5 – MAY 2013

18 Input/Output Ports

The CP3SP33 has 64 software-configurable general-purpose I/O pins (36 on the FBGA-144 package),

organized into four ports, named Port E, Port F, Port G, and Port H. All 16 pins on Ports E, F, and G and

three pins on 8-bit Port H have independently programmable MIWU channels, which give them the

capability to interrupt the CPU and wake up the system from low-power modes.

In addition to their general-purpose I/O function, most of the pins on Ports E, F, and G have alternate

functions for use with on-chip peripheral modules such as the UARTs and timers. Architecturally, there

may be two alternate functions for a port pin, and software must specify which function to select (A or B),

even when only one function is implemented. The alternate functions of all I/O pins are shown in

Table 18-2. To avoid glitches, software should first select the alternate function, then enable the alternate

function, and finally initialize the module which uses the alternate function.

The I/O pin characteristics are fully programmable. Each pin can be configured to operate as a TRI-

STATE output, push-pull output, input with weak pullup, input with weak pull-down, or high-impedance

input. Different pins within the same port can be individually configured to operate in different modes.

Figure 18-1 shows the I/O port pin logic. The register bits, multiplexers, and buffers allow the port pin to be

configured into the various operating modes.

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 input and output buffers are described in

Section 36.

Input/Output Ports

109

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CP3SP33SMS/NOPB Datasheet(PDF) 109 Page - Texas Instruments