Rev. 1.0, 02/00, page 468 of 1141
23.2.3
Second Slave Address Register (SARX)
7
SVAX6
0
R/W
6
SVAX5
0
R/W
5
SVAX4
0
R/W
4
SVAX3
0
R/W
3
SVAX2
0
R/W
0
FSX
1
R/W
2
SVAX1
0
R/W
1
SVAX0
0
R/W
Bit :
Initial value :
R/W :
SARX is an 8-bit readable/writable register that stores the second slave address and selects the
communication format. When the chip is in slave mode (and the addressing format is selected), if
the upper 7 bits of SARX match the upper 7 bits of the first frame received after a start condition,
the chip operates as the slave device specified by the master device. SARX is assigned to the
same address as ICDR, and can be written and read only when the ICE bit is cleared to 0 in ICCR.
SARX is initialized to H'01 by a reset and in hardware standby mode.
Bits 7 to 1
Second Slave Address (SVAX6 to SVAX0): Set a unique address in bits SVAX6 to
SVAX0, differing from the addresses of other slave devices connected to the I
2
C bus.
Bit 0
Format Select X (FSX): Used together with the FSX bit in SARX and the SW bit in
DDCSWR to select the communication format.
•
I
2
C bus format: addressing format with acknowledge bit
•
Synchronous serial format: non-addressing format without acknowledge bit, for master mode
only
•
Formatless transfer: non-addressing with or without an acknowledge bit and without detection
of start or stop condition, for slave mode only.
The FSX bit also specifies whether or not SARX slave address recognition is performed in slave
mode. For details, see the description of the FS bit in section 23.2.2, Slave Address Register
(SAR).