MAX7348AEP-T Maxim Integrated, MAX7348AEP-T Datasheet - Page 11

• Manufacturer Part Number: MAX7348AEP-T
• Description: Peripheral Drivers & Components - PCIs Low-EMI Key Switch & Sounder Controller
• Manufacturer: Maxim Integrated

Figure 7. Command Byte Received
Figure 8. Command and Single Data Byte Received
A write to the MAX7347/MAX7348/MAX7349s’ sounder
controller comprises the transmission of the
MAX7347/MAX7348/MAX7349s’ sounder slave address
with the R/W bit set to zero, followed by at least 1 com-
mand byte of information. The sounder controller ana-
lyzes each incoming data byte, and depending on the
state of the sounder controller’s 2-deep FIFO and the
contents of the command byte, the command byte is
added to the FIFO or it overwrites the last FIFO data
item (Table 16).
A read from the MAX7347/MAX7348/MAX7349s’ sounder
controller comprises the transmission of the
MAX7347/MAX7348/MAX7349s’ sounder slave address
with the R/W bit set to 1. The master can now read n con-
secutive bytes from the MAX7347/MAX7348/MAX7349,
each byte being a snapshot of the FIFO status of the
sounder controller (Table 16). If the master wishes to poll
the sounder controller until there is room for another com-
mand to be sent, the master can read bytes continuously
from the sounder controller until the information is satis-
factory and then issue a STOP condition.
Message Format for Reading the Sounder
S
Message Format for Writing the Sounder
ACKNOWLEDGE FROM MAX7347/MAX7348/MAX7349
SLAVE ADDRESS
ACKNOWLEDGE FROM MAX7347/MAX7348/MAX7349
______________________________________________________________________________________
S
2-Wire Interfaced Low-EMI Key Switch
COMMAND BYTE IS STORED ON RECEIPT OF
R/W
SLAVE ADDRESS
0
ACKNOWLEDGE CONDITION
A
ACKNOWLEDGE FROM MAX7347/MAX7348/MAX7349
D7
Controller
Controller
R/W
D6
D5
COMMAND BYTE
0
D4
ACKNOWLEDGE FROM MAX7347/MAX7348/MAX7349
A
D3
and Sounder Controllers
D7
If the MAX7347/MAX7348/MAX7349 are operated on a 2-
wire interface with multiple masters, a master reading the
MAX7347/MAX7348/MAX7349 should use a repeated
start between the write that sets the MAX7347/MAX7348/
MAX7349s’ address pointer, and the read(s) that takes
the data from the location(s). This is because it is possi-
ble for master 2 to take over the bus after master 1 has
set up the MAX7347/MAX7348/MAX7349s’ address
pointer but before master 1 has read the data. If master 2
subsequently resets the MAX7347/MAX7348/MAX7349s’
address pointer, then master 1’s read may be from an
unexpected location.
D2
Table 4. Key-Scan Command Address
Autoincrement Rules
Keys FIFO
Debounce
Autorepeat
Interrupt
Configuration
Port
Key Sound
Alert Sound
D6
FUNCTION
D1
REGISTER
D5
D0
COMMAND BYTE
D4
A
ACKNOWLEDGE FROM MAX7347/MAX7348/MAX7349
Operation with Multiple Masters
D3
D7
D2
D6
CODE (hex)
ADDRESS
D1
D5
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
D0
D4
1 BYTE
DATA BYTE
D3
A
D2
P
AUTOINCREMENT
COMMAND BYTE ADDRESS
ADDRESS (hex)
D1
AUTOINCREMENT
D0
0x00
0x02
0x03
0x04
0x05
0x06
0x07
0x00
A
P
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