lm8333ggr8x National Semiconductor Corporation, lm8333ggr8x Datasheet - Page 10

• Manufacturer Part Number: lm8333ggr8x
• Description: Mobile I/o Companion Supporting Key-scan, I/o Expansion, Pwm, And Access.bus Host Interface
• Manufacturer: National Semiconductor Corporation

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Every transfer is preceded by a Start condition (S) or a Re-
peated Start condition (RS). The latter occurs when a com-
mand follows immediately upon another command without an
intervening Stop condition (P). A Stop condition indicates the
end of transmission. Every byte is acknowledged (A) by the
receiver.
The first byte in a write from the host to the LM8333 is 0xA2,
and the first byte in a read is 0xA3. This byte is composed of
a 7-bit slave address in bits 7:1 and a direction bit in bit 0. The
direction bit is 0 on writes from the host to the slave and 1 on
reads from the slave to the host.
The second byte sends the command. The commands are
listed in Table 5. In the example, the READ_INT command
(0xD0) reads the interrupt code.
The slave address is repeated in the third byte, with the di-
rection bit set to 1. The Start (or Repeated Start) condition
must be repeated whenever the slave address or the direction
bit is changed. In this case, the direction bit is changed.
9.5 HOST READ COMMANDS
Some host commands include one or more data bytes read
from the LM8333. Figure 9 shows a READ_INT command
which consists of an address byte, a command byte, a second
address byte, and a data byte.
The first address byte is sent with the direction bit driven low
to indicate a write transaction of the command to the LM8333.
The second address byte is sent with the direction bit undriven
FIGURE 8. Host Write Command
FIGURE 9. Host Read Command
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The data is sent from the slave to the host in the fourth byte.
When the master is the receiver, it sends a negative acknowl-
edgement (NA) to indicate the end of the data.
9.4 HOST WRITE COMMANDS
Some host commands include one or more data bytes written
to the LM8333. Figure 8 shows a SET_EXT_INT command,
which consists of an address byte, a command byte, and one
data byte.
The first byte is composed of a 7-bit slave address in bits 7:1
and a direction bit in bit 0. The state of the direction bit is 0 on
writes from the host to the slave and 1 on reads from the slave
to the host.
The second byte sends the command. The commands are
listed in Figure 9. The SET_EXT_INT command is 0xD1.
The third byte send the data, in this case configuring
GEN_IO_0 as an external interrupt input.
(pulled high) to indicate a read transaction of the data from
the LM8333.
The Start (or Repeated Start) condition must be repeated
whenever the slave address or the direction bit is changed. In
this case, the direction bit is changed.
The data is sent from the slave to the host in the fourth byte.
This byte ends with a negative acknowledgement (NACK) to
indicate the end of the data.
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