CHAPTER 16 I
2
C BUS
User’s Manual U16896EJ2V0UD
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16.10 Extension Code
(1) When the higher 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 signal (INTIIC0) is issued at the falling edge of the eighth clock.
The local address stored in the SVA0 register is not affected.
(2) If 11110xx0 is set to the SVA0 register by a 10-bit address transfer and 11110xx0 is transferred from the master
device, the results are as follows. Note that the INTIIC0 signal occurs at the falling edge of the eighth clock.
•
Higher 4 bits of data match: IICS0.EXC0 bit = 1
•
7 bits of data match:
IICS0.COI0 bit = 1
(3) Since the processing after the INTIIC0 signal occurs differs according to the data that follows the extension code,
such processing is performed by software.
The slave that has received an extension code is always under communication, even if the addresses mismatch.
For example, when operation as a slave is not desired after the extension code is received, set the IICC0.LREL0
bit to 1 and the CPU will enter the next communication wait state.
Table 16-4. 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
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