TNETV1002IDZHK datasheet(48/102 Pages) TI1

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MCU Subsystem Functional Overview

June 2001 -- Revised December 2002

SPRS180C

Table 4--2. GPIO Control/Status Bits

BIT NAME

DESCRIPTION

I/O bit:

Writable when I/O is configured as an output (cio=0)

Reads value on I/O pin when I/O is configured as an input (cio=1)

cio

Configure I/O:

0: output

1: input (default)

gpio_irqA

SeeTable4--3

gpio_irqB

SeeTable4--3

ddio

Delta detect bit:

If gpio is configured as an output (cio=0), always reads as ‘0’

If gpio is configured as an input (cio=1), reads a ‘1’ if io has changed since ddio was last cleared

gpio_en

Selects register for muxed GPIOs:

0: other signal

1: gpio (default)

Non-shared GPIOs are always available at the i/o pin independent of the value of gpio_en

Table 4--3. GPIO_IRQ Bits Definition

gpio_irqB

gpio_irqA

FUNCTION

The associated device pin does not cause assertion of a GPIO interrupt.

A rising edge on the associated device pin causes assertion of a GPIO interrupt.

A falling edge on the associated device pin causes assertion of a GPIO interrupt.

Any change on the associated device pin causes assertion of a GPIO interrupt.

The configuration/status bits are accessible through 12 memory-mapped registers: GPIO_IO, KBGPIO_IO,

GPIO_CIO, KBGPIO_CIO, GPIO_IRQA, KBGPIO_IRQA, GPIO_IRQB, KBGPIO_IRQB, GPIO_DDIO,

KBGPIO_DDIO, GPIO_EN and KBGPIO_EN.

The pins KBGPIO(15:8) have on-chip pullup resistors, making them suitable for use as keypad row inputs.

To configure the 5471 for an 8x8 keypad [with keypad columns connected to KBGPIO(7:0) and rows

connected to KBGPIO(15:8)], use the following settings:

•

KBGPIO(15:8) pins are configured as inputs (cio=1) for row lines

•

KBGPIO(7:0) pins are configured as outputs (cio=0) for column lines

Keypad scanning can be done by setting the output values on all of the column KBGPIO pins to 0 and enabling

KBGPIO(15:8) interrupts. When a KBGPIO(15:8) interrupt is seen, all but one of the the KGBPIO column

output values are be changed to 1, and then the KBGPIO row pins are read. If the KBGPIO pin row input value

is all 1s, then there are no keys in the column currently driven to 0 that are set. Any bit in the KGBPIO pin

row input value that is 0 indicates a closed switch. Next, select a different column by writing a new value to

KBGPIO column pins with just one output pin value 0 and the remainder 1. Repeat the KBGPIO row read and

check for closed switches. Repeat this for each column in the keyboard array. Once the keypad has been read,

the interrupt service routine should set all column outputs back to 0 so that the next key press may be sensed.

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