MAX7315 Ver la hoja de datos (PDF) - Maxim Integrated

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MAX7315

8-Port I/O Expander with LED Intensity Control, Interrupt, and Hot-Insertion Protection

Maxim Integrated 

8-Port I/O Expander with LED Intensity

Control, Interrupt, and Hot-Insertion Protection

COMMAND BYTE IS STORED ON RECEIPT OF

STOP CONDITION

ACKNOWLEDGE FROM MAX7315

D15 D14 D13 D12 D11 D10 D9 D8

S

SLAVE ADDRESS

0A

COMMAND BYTE

AP

R/W

Figure 7. Command Byte Received

ACKNOWLEDGE FROM MAX7315

HOW COMMAND BYTE AND DATA BYTE MAP INTO

MAX7315'S REGISTERS

ACKNOWLEDGE FROM MAX7315

ACKNOWLEDGE FROM MAX7315

D15 D14 D13 D12 D11 D10 D9 D8

ACKNOWLEDGE FROM MAX7315

D7 D6 D5 D4 D3 D2 D1 D0

S

SLAVE ADDRESS

0A

COMMAND BYTE

A

DATA BYTE

AP

1

R/W

BYTE

AUTOINCREMENT MEMORY ADDRESS

Figure 8. Command and Single Data Byte Received

HOW COMMAND BYTE AND DATA BYTE MAP INTO

MAX7315'S REGISTERS

ACKNOWLEDGE FROM MAX7315

ACKNOWLEDGE FROM MAX7315

D15 D14 D13 D12 D11 D10 D9 D8

ACKNOWLEDGE FROM MAX7315

D7 D6 D5 D4 D3 D2 D1 D0

S

SLAVE ADDRESS

0A

COMMAND BYTE

A

DATA BYTE

AP

N

R/W

BYTES

AUTOINCREMENT MEMORY ADDRESS

Figure 9. n Data Bytes Received

Any bytes received after the command byte are data

bytes. The first data byte goes into the internal register

of the MAX7315 selected by the command byte (Figure

8). If multiple data bytes are transmitted before a STOP

condition is detected, these bytes are generally stored

in subsequent MAX7315 internal registers because the

command byte address autoincrements (Table 2). A

diagram of a write to the output ports registers (blink

phase 0 register or blink phase 1 register) is given in

Figure 10.

Message Format for Reading

The MAX7315 is read using the MAX7315’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 MAX7315’s command byte by performing a

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

tive bytes from the MAX7315 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 register is shown

in Figure 10 reflecting the states of the ports.

Operation with Multiple Masters

If the MAX7315 is operated on a 2-wire interface with

multiple masters, a master reading the MAX7315 should

use a repeated start between the write, which sets the

MAX7315’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 MAX7315’s address pointer but before

master 1 has read the data. If master 2 subsequently

changes the MAX7315’s address pointer, then master

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

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