LM8322JGR8 NSC [National Semiconductor], LM8322JGR8 Datasheet - Page 26

• Manufacturer Part Number: LM8322JGR8
• Description: Mobile I/O Companion Supporting Key-Scan, I/O Expansion, PWM, and ACCESS.bus Host Interface
• Manufacturer: NSC [National Semiconductor]

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16.5 HOST READ COMMANDS
Some host commands include one or more data bytes read
from the LM8322. Figure 17 shows a READ_PORT_SEL
command which consists of an address byte, a command
byte, a second address byte, and two data bytes.
The first address byte is sent with the direction bit driven low
to indicate a write transaction of the command to the LM8322.
The second address byte is sent with the direction bit undriven
(pulled high) to indicate a read transaction of the data from
the LM8322.
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.
16.6 INTERRUPTS
The IRQ output may be asserted on these conditions:
•
Any new key-event after the last interrupt was asserted but
not yet acknowledged by reading the interrupt code.
FIGURE 16. Host Write Command
FIGURE 17. Host Read Command
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The bus master can send any number of Repeated Start con-
ditions without releasing control of the bus. This technique
can be used to implement atomic transactions, in which the
bus master sends a command and then reads a register with-
out allowing any other device to get control of the bus between
these events.
The data is sent from the slave to the host in the fourth and
fifth bytes. The fifth byte ends with a negative acknowledge-
ment (NACK) to indicate the end of the data.
•
•
Termination of a PWM script (END command).
Any error condition, which is indicated by the error code.
30013617
30013616