MAX7322 Maxim, MAX7322 Datasheet - Page 11

• Manufacturer Part Number: MAX7322
• Description: The MAX7322 2-wire serial-interfaced peripheral features four push-pull outputs and four input ports with selectable internal pullups
• Manufacturer: Maxim

The MAX7322 has a 7-bit-long slave address (Figure 5).
The eighth bit following the 7-bit slave address is the R/W
bit. It is low for a write command, and high for a read
command.
The first (A6), second (A5), and third (A4) bits of the
MAX7322 slave address are always 1, 1, and 0.
Connect AD2 and AD0 to GND, V+
select slave address bits A3, A2, A1, and A0. The
MAX7322 has 16 possible slave addresses (Table 2),
allowing up to 16 MAX7322 devices on an I
The MAX7322 is accessed through an I
The transition flags are cleared, and INT is deasserted
each time the device acknowledges the I
address.
A single-byte read from the MAX7322 returns the sta-
tus of the four input ports and the four output ports
(read back as inputs).
A 2-byte read returns the status of the four input ports
and the four output ports (as for a single-byte read), fol-
lowed by the transition flags for the four input ports.
Figure 5. Slave Address
.
SDA
SCL
MSB
1
______________________________________________________________________________________
1
Accessing the MAX7322
0
4 Push-Pull Outputs and 4 Inputs
,
SDA, or SCL to
Slave Address
2
2
C interface.
C bus.
2
A3
C slave
A2
I
A multibyte read (more than 2 bytes before the I
STOP bit) repeatedly returns the port data, alternating
with the transition flags. As the data is resampled for
each transmission, and the transition flags are reset
each time, a multibyte read continuously returns the
current data and identifies any changing ports.
If a port data change occurs during the read sequence,
INT is reasserted after the I
does not generate another interrupt during a single-
byte or multibyte read.
Port data is sampled during the preceding I
acknowledge bit (the acknowledge bit for the I
address in the case of a single-byte or 2-byte read).
A single-byte write to the MAX7322 sets the logic state
of the four output ports and the 4-bit interrupt mask
resistor, and clears both the internal transition flags and
the INT output when the device acknowledges the
slave address byte.
A multibyte write to the MAX7322 repeatedly sets the
logic state of the four output ports and the 4-bit inter-
rupt mask register.
2
C Port Expander with
A1
LSB
A0
2
C STOP bit. The MAX7322
R/W
ACK
2
C slave
2
2
11
C
C