MAX7365 Maxim, MAX7365 Datasheet - Page 14

• Manufacturer Part Number: MAX7365
• Description: The MAX7365 is an I²C-interfaced peripheral that provides microprocessors with management of up to 56 key switches
• Manufacturer: Maxim

A write to the device comprises the transmission of the
slave address with the R/W bit set to zero, followed by at
least 1 byte of information. The first byte of information is
the command byte. The command byte determines which
register of the device is to be written by the next byte, if
received. If a STOP condition is detected after the com-
mand byte is received, the device takes no further action
(Figure
Any bytes received after the command byte are data
bytes. The first data byte goes into the internal register of
the device selected by the command byte
If multiple data bytes are transmitted before a STOP condi-
tion is detected, these bytes are generally stored insub-
sequent internal registers of the device because the com-
mand-byte address generally autoincrements
Figure 5. Command Byte Received
Figure 6. Command and Single Data Byte Received
Figure 7. N Data Bytes Received
S
S
5) beyond storing the command byte.
SLAVE ADDRESS
SLAVE ADDRESS
ACKNOWLEDGE FROM MAX7365
ACKNOWLEDGE FROM MAX7365
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S
Message Format for Writing
the Keyscan Controller
COMMAND BYTE IS STORED ON RECEIPT OF
Key-Switch Controller with GPIO Ports
R/W
R/W
ACKNOWLEDGE FROM MAX7365
SLAVE ADDRESS
0
0
ACKNOWLEDGE CONDITION
A
A
D7
D7
(Figure
R/W
(Table
D6
D6
6).
D5
D5
COMMAND BYTE
ACKNOWLEDGE FROM MAX7365
COMMAND BYTE
5).
0
ACKNOWLEDGE FROM MAX7365
D4
D4
A
D3
D3
1MHz I
D7
The device is read using the 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 generally autoincrements after each data
byte is read using the same rules as for a write
Thus, a read is initiated by first configuring the device’s
command byte by performing a write
ter can now read N consecutive bytes from the device,
with the first data byte being read from the register
addressed by the initialized command byte. When per-
forming read-after-write verification, remember to reset
the command byte’s address because the stored com-
mand byte address is generally autoincremented after
the write
D2
D2
D6
D1
D1
ACKNOWLEDGE FROM MAX7365
D5
COMMAND BYTE
D0
D0
(Figure
D4
2
A
A
D3
C-Interfaced 8 x 7
D7
D7
7,
D2
Table
Message Format for Reading
D6
D6
D1
D5
D5
5).
ACKNOWLEDGE FROM MAX7365
D0
the Keyscan Controller
ACKNOWLEDGE FROM MAX7365
D4
D4
N BYTES
DATA BYTE
1 BYTE
DATA BYTE
A
D3
D3
P
MAX7365
D2
D2
(Figure
COMMAND BYTE ADDRESS
COMMAND BYTE ADDRESS
D1
D1
AUTOINCREMENT
AUTOINCREMENT
D0
D0
5). The mas-
(Table
A
A
P
P
5).