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CHAPTER 15 I
C INTERFACE
■ Other Items
•
After arbitration lost occurs, check whether or not the local device is addressed using
software.
When arbitration lost occurs, the device becomes a slave in terms of hardware. However, after
one-byte transfer is completed, both the CLK and DATA lines are pulled to L. Thus, if the
device is not addressed, immediately open the CLK and DATA lines. If the device is
addressed, open the CLK and DATA lines after preparing for slave transmission or reception.
All of these things must be processed using software.
•
Since the I
transfer is completed or when an interrupt condition is met.
Since multiple interrupt conditions must be checked using one interrupt, each of the flags must
be checked by the interrupt routine. The following lists the interrupt conditions used when one-
byte transfer is completed:
•
The device is a bus master.
•
The device is an addressed slave.
•
A general call address is received.
•
Arbitration lost occurs.
•
When arbitration lost is detected, an interrupt source is generated, not immediately but after
one-byte transfer is completed. When arbitration lost is detected, the device becomes a slave
in terms of hardware. However, in slave mode, a total of nine clocks must be output before an
interrupt source can be generated. Thus, since an interrupt source is not immediately
generated, no processing can be performed after arbitration lost occurs.
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C bus has only one interrupt, an interrupt source is generated when one-byte
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