LM8333 datasheet(9/17 Pages) NSC

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7.0 Device Operation (Continued)

Table 4 shows the pin configuration for all four combinations

of control bit settings (data output and direction) for the

general-purpose I/O pins. GEN_IO_3 cannot be put into the

high impedance (Hi-Z) input mode. When programmed as

an input, it can only be configured as an input with a weak

pullup.

TABLE 4. General Purpose I/O Pin Configuration

GEN_IO_DIR

Bit

GEN_IO_OUT

Bit

Direction

State

Input

Hi-Z

Input

Weak

Pullup

Output

Drive Low

Output

Drive High

7.2.3 External Interrupts

When the GEN_IO_0 or GEN_IO_1 pins are configured as

inputs, a SET_EXT_INT command (0xD1) can be used to

enable receiving external interrupts on either or both of these

pins. Setting the EX_0 or EX_1 bits in the data byte of the

SET_EXT_INT command (as shown in Figure 6) enables the

corresponding pin as an external interrupt input. When en-

abled as an interrupt input, any rising or falling edge causes

the IRQ output to be asserted. If the LM8333 was in Halt

mode, it also wakes up into Active mode.

When both GEN_IO_0 and GEN_IO_1 are configured as

interrupt inputs, bits 1 and 2 of the interrupt code indicate

which input asserted the interrupt. However, if only one of

GEN_IO_0 or GEN_IO_1 is configured as an interrupt input,

both bits 1 and 2 of the interrupt code will be set when an

interrupt occurs.

TABLE 5. Interface Commands for Controlling the LM8333

Function

Cmd

Dir

Data Bits

Data

Description

FIFO_READ

0x20

128

Event Codes from

FIFO

Read an event from the FIFO.

Maximum 14 event codes stored in the FIFO.

MSB = 1: key pressed.

MSB = 0: key released.

RPT_FIFO_READ

0x21

128

Event Codes from

FIFO

Repeats a FIFO read without advancing the FIFO

pointer, for example to retry a read after an error.

Maximum 14 event codes stored in the FIFO.

MSB = 1: key pressed.

MSB = 0: key released.

DEBOUNCE

0x22

nnnn nnnn

Default is 10 ms. Valid range 1255.

Time ~ nx4ms

GEN_IO_IN

0x30

0000 nnnn

Read port data.

GEN_IO_OUT

0x31

0000 nnnn

Specify port mode. (Drive 0 or 1 when the port is

configured as an output; select Hi-Z or pullup when

the port is configured as an input.)

GEN_IO_DIR

0x32

0000 nnnn

Select port direction (input or output).

PWM_HI

0x40

(n+1) x t

Sets the low pulse time of the PWM signal.

PWM_LO

0x41

(n+1) x t

Sets the high pulse time of the PWM signal.

PWM_CTL

0x42

0000 0nnn

Activate, reactivate, or stop PWM.

READ_INT

0xD0

0000 nnnn

Reads the interrupt code, acknowledges the interrupt,

deasserts the IRQ output, and clears the code.

SET_EXT_INT

0xD1

0000 00nn

Enables/disables external interrupts on GEN_IO_0 and

GEN_IO_1.

READ_STAT

0xE0

000n nnnn

Status Information.

SCAN_REQ

0xE3

Requests rescanning the keypad (for example, after

an error was reported).

ACTIVE

0xE4

nnnn nnnn

Specifies the time after the last event during which the

LM8333 stays active before entering Halt mode. The

active time must be greater than the debounce time.

READ_ERROR

0xF0

0nnn nnnn

Reads and clears the error code.

20210608

FIGURE 6. SET_EXT_INT Command Data Byte

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