M306H7MG-XXXFP Datasheet, PDF (151/329 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER with DATA ACQUISITION CONTROLLER

M306H7MG-XXXFP/MC-XXXFP/FGFP
11. MULTI-MASTER I²C BUS INTERFACE
(5) I²C control register
The I²C control register controls the data communication format.
• Bits 0 to 2: bit counter (BC0−BC2)
These bits decide the number of bits for the next 1-byte data to be transmitted. An interrupt request signal occurs
immediately after the number of bits specified with these bits are transmitted.
When a START condition is received, these bits become “0002” and the address data is always transmitted and
received in 8 bits.
Note: When the bit counter value = “1112,” a STOP condition and START condition cannot be waited.
• Bit 3: I²C-BUS interface use enable bit (ESO)
This bit enables usage of the multimaster I²C-BUS interface i. When this bit is set to “0,” the use disable status is
provided, so the SDA and the SCL become high-impedance. When the bit is set to “1,” use of the interface is
enabled.
When ESO = “0,” the following is performed.
• PIN = “1,” BB = “0” and AL = “0” are set (they are bits of the I²C status register).
• Writing data to the I²C data shift register and the I²C transmit buffer register is disabled.
• Bit 4: data format selection bit (ALS)
This bit decides whether or not to recognize slave addresses. When this bit is set to “0,” the addressing format is
selected, so that address data is recognized. When a match is found between a slave address and address data as a
result of comparison or when a general call (refer to “(6) I²C status register,” bit 1) is received, transmission
processing can be performed. When this bit is set to “1,” the free data format is selected, so that slave addresses
are not recognized.
• Bit 5: addressing format selection bit (10BIT SAD)
This bit selects a slave address specification format. When this bit is set to “0,” the 7-bit addressing format is
selected. In this case, only the high-order 7 bits (slave address) of the I²C address register are compared with
address data. When this bit is set to “1,” the 10-bit addressing format is selected, all the bits of the I²C address
register are compared with address data.
Rev.2.10 Oct 25, 2006 Page 151 of 326
REJ03B0152-0210