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CHAPTER 10 SERIAL INTERFACE FUNCTION
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10.3.7 Address match detection method
When in I
slave address.
Address match detection is performed automatically by hardware. An interrupt request (INTIICn) occurs when a
local address has been set to the slave address register (SVAn) and when the address set to SVAn matches the
slave address sent by the master device, or when an extension code has been received (n = 0, 1).
2
C bus mode, the master device can select a particular slave device by transmitting the corresponding
10.3.8 Error detection
In I
2
C bus mode, the status of the serial data bus (SDAn) during data transmission is captured by the IIC shift
register n (IICn) of the transmitting device, so the IICn data prior to transmission can be compared with the
transmitted IICn data to enable detection of transmission errors. A transmission error is judged as having occurred
when the compared data values do not match (n = 0, 1).
10.3.9 Extension code
(1) When the high-order 4 bits of the receive address are either 0000 or 1111, the extension code flag (EXCn) is
set for extension code reception and an interrupt request (INTIICn) is issued at the falling edge of the eighth
clock (n = 0, 1).
The local address stored in the slave address register (SVAn) is not affected.
(2) If 11110xx0 is set to SVAn by a 10-bit address transfer and 11110xx0 is transferred from the master device, the
results are as follows. Note that INTIICn occurs at the falling edge of the eighth clock (n = 0, 1).
High-order four bits of data match: EXCn = 1
Seven bits of data match: COIn = 1
Note
Note
Note
EXCn: Bit 5 of IIC status register n (IICSn)
COIn : Bit 4 of IIC status register n (IICSn)
(3) Since the processing after the interrupt request occurs differs according to the data that follows the extension
code, such processing is performed by software.
For example, when operation as a slave is not desired after the extension code is received, set LRELn to 1 and
the CPU will enter the next communication wait state.
Table 10-4. Extension Code Bit Definitions
Slave address
R/W bit
Description
0000 000
0
General call address
0000 000
1
Start byte
0000 001
X
CBUS address
0000 010
X
Address that is reserved for different bus format
1111 0xx
X
10-bit slave address specification