TMPR3911 datasheet(222/462 Pages) TOSHIBA

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Chapter 9 I/O Module

9-4

9.2.2

General Purpose I/O Ports

Each of the 7 general purpose I/O ports can be independently programmed as an input or output port.

Each port can generate a separate positive and negative edge interrupt. Figure 9.2.1 shows a block

diagram of a general purpose I/O port.

Each port consists of a bi-directional buffer connected to the appropriate TMPR3911/12 pin. For the

input direction, the output signal from the input buffer is routed directly to a debounce circuit. This

circuit performs a 16 ms to 24 ms debounce of the input signal. The debounce select control signal from

the I/O Debounce Select Register is used to select between the debouncer output and the direct signal

from the port input buffer, which bypasses the debouncer. This selected signal is then routed to the I/O

Data Input Register and to the Interrupt Flip-Flop. Reading a specific bit location within the I/O Data

Input Register returns the logic state of the respective general purpose I/O pin (either direct or

debounced), regardless of whether that pin is configured as an output or input. If the pin is configured as

an input, the value read is the logic state of the pin as driven by an external source. If the pin is

configured as an output, the value read is the logic state of the pin as driven by the TMPR3911/12.

For the output direction, the input signal to the output buffer is routed from the appropriate bit within

the I/O Data Output Register. The output enable control signal for the tri-state output buffer is routed

from the I/O Direction Register.

The I/O Power-Down Register provides independent control bits for controlling the power-down

state for each of the 7 general purpose I/O ports. If a particular I/O port is configured to power down,

then the output will be gated low and a Pull-Down resistor will be enabled whenever the device powers

down. Device power down occurs when either VCC3 or VCCON (internal signal) become de-asserted.

The Pull-Down will prevent the input from floating if the general purpose I/O port is configured as an

input.

TMPR3911 Datasheet(PDF) 222 Page - Toshiba Semiconductor