Datasheet

MAX7370
8 x 8 Key-Switch Controller and LED Driver/GPIOs
with I2C Interface and High Level of ESD Protection
17Maxim Integrated
Message Format for Reading
the Keyscan Controller
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
(Table 4). Thus, a read is initiated by first configuring the
device’s command byte by performing a write (Figure 6).
The master can now read N consecutive bytes from the
device, with the first data byte being read from the reg-
ister addressed by the initialized command byte. When
performing read-after-write verification, remember to
reset the command byte’s address because the stored
command byte address is generally autoincremented
after the write (Figure 8, Table 4).
Figure 7. Command and Single Data Byte Received
Figure 6. Command Byte Received
Figure 8. N Data Bytes Received
Table 4. Autoincrement Rules
REGISTER
FUNCTION
ADDRESS
CODE (hex)
AUTOINCREMENT
ADDRESS (hex)
Keys FIFO 0x00 0x00
Autosleep 0x06 0x00
All other key
switches
0x01 to 0x05 Addr + 0x01
All other GPIOs 0x30 to 0x5B Addr + 0x01
SAAP0SLAVE ADDRESS COMMAND BYTE
D7 D6 D5 D4 D3 D2 D1 D0
COMMAND BYTE IS STORED ON RECEIPT OF
ACKNOWLEDGE CONDITION
ACKNOWLEDGE FROM MAX7370
ACKNOWLEDGE FROM MAX7370
R/W
SA
AA
P0SLAVE ADDRESS COMMAND BYTE DATA BYTE
1 BYTE
AUTOINCREMENT
COMMAND BYTE ADDRESS
D7 D6 D5 D4 D3 D2 D1 D0 D1 D0D3 D2D5 D4D7 D6
ACKNOWLEDGE FROM MAX7370
ACKNOWLEDGE FROM MAX7370
ACKNOWLEDGE FROM MAX7370
R/W
SA
AA
P0SLAVE ADDRESS COMMAND BYTE DATA BYTE
N BYTES
AUTOINCREMENT
COMMAND BYTE ADDRESS
D7 D6 D5 D4 D3 D2 D1 D0 D1 D0D3 D2D5 D4D7 D6
ACKNOWLEDGE FROM MAX7370
ACKNOWLEDGE FROM MAX7370
ACKNOWLEDGE FROM MAX7370
R/W