LM8323 datasheet(12/46 Pages) TI2

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LM8323

SNLS273A – JULY 2010 – REVISED MARCH 2013

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INITIALIZATION EXAMPLE

In the following example, the LM8323 is configured as:

•

Keypad matrix configuration is 8 × 4.

•

Rotary encoder interface enabled.

•

GPIO_03 through GPIO_07 are available to use as GPIO pins.

•

GPIO_03 is an output driven low.

•

GPIO_4 and GPIO_5 are outputs driven high.

•

GPIO_06 and GPIO_07 are inputs with weak pulldowns.

•

GPIO_14 and GPIO_15 are inputs with weak pullups.

•

The PWM clock source is the internal execution clock divided by 64 (about 32 kHz).

Most of these settings can be verified by executing commands such as READ_CONF, READ_PORT_SEL,

READ_CLOCK, etc.

ALL GPIO pin states can be read using the READ_PORT_STATE command, without regard to whether the pin is

an input or an output.

An open-drain signal can be created by alternating between input mode and driving the output low.

All GPIOs can sink and source 16 mA when configured as an output.

Command

Encoding

Parameter 1

Parameter 2

Description

Selects 36-pin package and disables the two digital

WRITE_CFG

0x81

0x40

multiplexers.

SLOWCLKOUT disabled, no external 32.768 kHz clock

WRITE_CLK

0x93

0x08

required, PWM clock source is internal.

SET_KEY_SIZE

0x90

0x84

Selects a keypad matrix size of 8 × 4.

Sets the active time to about 300 milliseconds (75 × 4

SET_ACTIVE

0x8B

0x4B

milliseconds).

Sets the key debouncing time to about 12 milliseconds (3 × 4

SET_DEBOUNCE

0x8F

0x03

ms). This is actually the default and would not have to be

performed.

Configure GPIO_03, GPIO_04, and GPIO_05 as outputs.

WRITE_PORT_SEL

0x85

0x00

0x38

Configure GPIO_06, GPIO_07, GPIO_14, and GPIO_15 as

inputs.

Set the direction for the pullup/pulldown devices on GPIO_06

WRITE_PULL_DOWN

0x84

0x00

0x3F

and GPIO_07 to pulldown. Set the direction for the

pullup/pulldown devices on GPIO_14 and GPIO_15 to pullup.

Set GPIO_04 and GPIO_05 to drive high. Enable the pullups

WRITE_PORT_STATE

0x86

0xC0

0xF0

on GPIO_06, GPIO_07, GPIO_14, and GPIO_15.

HALT MODE

The fully static architecture of the LM8323 allows stopping the internal RC clock in Halt mode, which reduces

power consumption to the minimum level. Figure 7 shows the current in Halt mode at the maximum VCC (1.98V)

from 25°C to +85°C.

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