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CHAPTER 18 SERIAL INTERFACE (IIC0) (
μ
PD780024Y, 780034Y SUBSERIES ONLY)
18.5.9 Address match detection method
When in I
2
C bus mode, the master device can select a particular slave device by transmitting the corresponding
slave address.
Address match can be detected automatically by hardware. An interrupt frequency (INTIIC0) occurs when a local
address has been set to the slave address register (SVA0) and when the address set to SVA0 matches the slave
address sent by the master device, or when an extension code has been received.
18.5.10 Error detection
During I
2
C bus mode, the status of the serial data bus (SDA0) during data transmission is captured by the IIC shift
register (IIC0) of the transmitting device, so the IIC0 data prior to transmission can be compared with the transmitted
IIC0 data to enable detection of transmission errors. A transmission error is judged as having occurred when the
compared data values do not match.
18.5.11 Extension code
(1) When the high-order 4 bits of the receive address are either “0000” or “1111”, the extension code flag (EXC0)
is set for extension code reception and an interrupt request (INTIIC0) is issued at the falling edge of the eighth
clock. The local address stored in the slave address register (SVA0) is not affected.
(2) If “111110
××
” is set to SVA0 by a 10-bit address transfer and “111110
××
0” is transferred from the master device,
the results are as follows. Note that INTIIC0 occurs at the falling edge of the eighth clock.
High-order four bits of data match: EXC0 = 1
Note
Seven bits of data match: COI0 = 1
Note
Note
EXC0 : Bit 5 of IIC status register (IICS0)
COI0 : Bit 4 of IIC status register (IICS0)
(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, after the extension code is received, if you do not wish to operate the target device as a slave
device, you can set bit 6 (LREL0) of the IIC control register (IIC0) to “1” to set the standby mode for the next
communication operation.
Table 18-3. Extension Code Bit Definitions
Slave address
R/W bit
Description
0000 000
0
General call address
0000 000
1
Start byte
0000 001
×
CBUS address
0000 010
×
Address that is reserved for different bus format
1111 0
××
×
10-bit slave address specification