MAX7314 Ver la hoja de datos (PDF) - Maxim Integrated

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MAX7314

18-Port GPIO with LED Intensity Control, Interrupt, and Hot-Insertion Protection

Maxim Integrated 

18-Port GPIO with LED Intensity Control,

Interrupt, and Hot-Insertion Protection

WRITE TO OUTPUT PORTS REGISTERS (BLINK PHASE 0 REGISTERS/BLINK PHASE 1 REGISTERS)

SCL 1 2 3 4 5 6 7 8 9

SLAVE ADDRESS

COMMAND BYTE

SDA S A6 A5 A4 A3 A2 A1 A0 0 A 0 0 0 0 0 0 0 1 A MSB

DATA1

LSB A MSB

DATA2

LSB A P

START CONDITION

P7–P0

P15– P8

R/W ACKNOWLEDGE FROM SLAVE

ACKNOWLEDGE FROM SLAVE

ACKNOWLEDGE FROM SLAVE

DATA1 VALID

tDV

tDV

READ FROM INPUT PORTS REGISTERS

SCL

12345678

SLAVE ADDRESS

SDA S A6 A5 A4 A3 A2 A1 A0 1

9

A MSB

COMMAND BYTE

DATA1

START CONDITION

R/W ACKNOWLEDGE FROM SLAVE

P7–P0

P15–P8

DATA1

DATA5

DATA2

tDH

DATA3

LSB A MSB

DATA6

LSB NA P

ACKNOWLEDGE FROM MASTER

DATA4

STOP CONDITION

NO ACKNOWLEDGE FROM

MASTER

DATA6

tDS

INTERRUPT VALID/RESET

SCL 1 2 3 4 5 6 7 8

SLAVE ADDRESS

SDA S A6 A5 A4 A3 A2 A1 A0 1

9

A MSB

COMMAND BYTE

DATA2

START CONDITION

P7–P0

P15–P8

DATA1

R/W ACKNOWLEDGE FROM SLAVE

DATA3

DATA2

LSB A MSB

DATA4

LSB NA P

ACKNOWLEDGE FROM MASTER

STOP CONDITION

NO ACKNOWLEDGE FROM

MASTER

DATA4

INT

tIV

tIR tIV

tIR

STOP

CONDITION

DATA2 VALID

Figure 10. Read, Write, and Interrupt Timing Diagrams

Message Format for Reading

The MAX7314 is read using the MAX7314’s internally

stored command byte as an address pointer the same

way the stored command byte is used as an address

pointer for a write. The pointer autoincrements after

each data byte is read using the same rules as for a

write (Table 2). Thus, a read is initiated by first configur-

ing the MAX7314’s command byte by performing a

write (Figure 7). The master can now read n consecu-

tive bytes from the MAX7314 with the first data byte

being read from the register addressed by the initial-

ized command byte. When performing read-after-write

verification, remember to reset the command byte’s

address because the stored command byte address

has been autoincremented after the write (Table 2). A

diagram of a read from the input ports registers is

shown in Figure 10 reflecting the states of the ports.

Operation with Multiple Masters

If the MAX7314 is operated on a 2-wire interface with

multiple masters, a master reading the MAX7314 should

use a repeated start between the write, which sets the

MAX7314’s address pointer, and the read(s) that takes

the data from the location(s) (Table 2). This is because it

is possible for master 2 to take over the bus after master

1 has set up the MAX7314’s address pointer but before

master 1 has read the data. If master 2 subsequently

changes the MAX7314’s address pointer, then master

1’s delayed read can be from an unexpected location.

Command Address Autoincrementing

The command address stored in the MAX7314 circu-

lates around grouped register functions after each data

byte is written or read (Table 2).

10 ______________________________________________________________________________________

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