Set the interrupt enable I bit in the configuration register

to configure INT/O16 as the INT output (Table 4). Clear

interrupt enable to configure INT/O16 as the O16. O16

logic state is set by the 2 bits O1 and O0 in the configu-

ration register. O16 follows the rules for blinking select-

ed by the blink enable flag E in the configuration

register. If blinking is disabled, then interrupt output

control O0 alone sets the logic state of the INT/O16 pin.

If blinking is enabled, then both interrupt output con-

trols O0 and O1 set the logic state of the INT/O16 pin

according to the blink phase. PWM intensity control for

O16 is set by the 4 global intensity bits in the master

and O16 intensity register (Table 13).

Blink Mode

In blink mode, the output ports can be flipped between

using either the blink phase 0 registers or the blink

phase 1 registers. Flip control is by software control

(the blink flip flag B in the configuration register) (Table

4). If hardware flip control is needed, consider the

MAX7314, which includes a BLINK input, as well as

software control.

The blink function can be used for LED effects by pro-

gramming different display patterns in the two sets of

output port registers, and using the software or hard-

ware controls to flip between the patterns.

If the blink phase 1 registers are written with 0xFF, then

the BLINK input can be used as a hardware disable to,

for example, instantly turn off an LED pattern pro-

grammed into the blink phase 0 registers. This tech-

nique can be further extended by driving the BLINK

input with a PWM signal to modulate the LED current to

provide fading effects.

The blink mode is enabled by setting the blink enable

flag E in the configuration register (Table 4). When blink

mode is enabled, the state of the blink flip flag sets the

phase, and the output ports are set by either the blink

phase 0 registers or the blink phase 1 registers (Table 7).

The blink mode is disabled by clearing the blink enable

flag E in the configuration register (Table 4). When blink

mode is disabled, the state of the blink flip flag is

ignored, and the blink phase 0 registers alone control

the output ports.

16-Port I/O Expander with LED Intensity

Control, Interrupt, and Hot-Insertion Protection

16

______________________________________________________________________________________

Table 5. Ports Configuration Registers

REGISTER DATA

REGISTER

R/

W

ADDRESS

CODE

(HEX)

D7

D6

D5

D4

D3

D2

D1

D0

Ports configuration P7–P0

(1 = input, 0 = output)

0

Read back ports configuration P7–P0

1

0x06

OP7

OP6

OP5

OP4

OP3

OP2

OP1

OP0

Ports configuration P15–P8

(1 = input, 0 = output)

0

Read back ports configuration P15–P8

1

0x07

OP15

OP14

OP13

OP12

OP11

OP10

OP9

OP8

Table 6. Input Ports Registers

REGISTER DATA

REGISTER

R/

W

ADDRESS

CODE

(HEX)

D7

D6

D5

D4

D3

D2

D1

D0

Read input ports P7–P0

1

0x00

IP7

IP6

IP5

IP4

IP3

IP2

IP1

IP0

Read input ports P15–P8

1

0x01

IP15

IP14

IP13

IP12

IP11

IP10

IP9

IP8

Table 7. Blink Controls

BLINK

ENABLE

FLAG E

BLINK

FLIP

FLAG B

BLINK

FUNCTION

OUTPUT

REGISTERS

USED

0

X

Disabled

Blink phase 0

registers

0

Blink phase 0

registers

1

1

Enabled

Blink phase 1

registers

X = Don’t care.