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Functional description
45.5.2 10-bit address
For 10-bit addressing, 0x11110 is used for the first 5 bits of the first address byte.
Various combinations of read/write formats are possible within a transfer that includes
10-bit addressing.
45.5.2.1 Master-transmitter addresses a slave-receiver
The transfer direction is not changed. When a 10-bit address follows a START condition,
each slave compares the first 7 bits of the first byte of the slave address (11110XX) with
its own address and tests whether the eighth bit (R/W direction bit) is 0. It is possible that
more than one device finds a match and generates an acknowledge (A1). Each slave that
finds a match compares the 8 bits of the second byte of the slave address with its own
address, but only one slave finds a match and generates an acknowledge (A2). The
matching slave remains addressed by the master until it receives a STOP condition (P) or
a repeated START condition (Sr) followed by a different slave address.
Table 45-16. Master-transmitter addresses slave-receiver with a 10-bit
Slave
R/W
S
address
0
first 7 bits
11110 +
AD10 +
AD9
After the master-transmitter has sent the first byte of the 10-bit address, the slave-receiver
sees an I2C interrupt. User software must ensure that for this interrupt, the contents of the
Data register are ignored and not treated as valid data.
45.5.2.2 Master-receiver addresses a slave-transmitter
The transfer direction is changed after the second R/W bit. Up to and including
acknowledge bit A2, the procedure is the same as that described for a master-transmitter
addressing a slave-receiver. After the repeated START condition (Sr), a matching slave
remembers that it was addressed before. This slave then checks whether the first seven
bits of the first byte of the slave address following Sr are the same as they were after the
START condition (S), and it tests whether the eighth (R/W) bit is 1. If there is a match,
the slave considers that it has been addressed as a transmitter and generates acknowledge
A3. The slave-transmitter remains addressed until it receives a STOP condition (P) or a
repeated START condition (Sr) followed by a different slave address.
1252
address
Slave
A1
A2
address
second
byte
AD[8:1]
KV4x Reference Manual, Rev. 2, 02/2015
Preliminary
Data
A
...
Freescale Semiconductor, Inc.
Data
A/A
P
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