M16C28 Datasheet, PDF (282/423 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/Tiny SERIES

M16C/28 Group (M16C/28, M16C/28B)
16. MULTI-MASTER I²C bus INTERFACE
16.4 I²C0 Control Register 0 (S1D0)
The S1D0 register controls data communication format.
16.4.1 Bits 0 to 2: Bit Counter (BC0–BC2)
The BC2 to BC0 bits decide how many bits are in one byte data transferred next. After the selected
numbers of bits are transferred successfully, I²C bus interface interrupt request is gnerated and the
BC2 to BC0 bits are reset to "0002". At this time, if the ACK-CLK bit in the S20 register is set to "1" (with
ACK clock), one bit for ACK clock is added to the numbers of bits selected by the BC2 to BC0 bits.
In addition, the BC2 to BC0 bits become "0002" even though the START condition is detected and the
address data is transferred in 8 bits.
16.4.2 Bit 3: I²C Interface Enable Bit (ES0)
The ES0 bit enables to use the multi-master I²C bus interface. When the ES0 bit is set to “0”, I²C bus
interface is disabled and the SDA and SCL pins are placed in a high-h-impedance state. When the
ES0 bit is set to “1”, the interface is enabled.
When the ES0 bit is set to “0”, the process is followed.
1)The bits in the S10 register are set as MST = "0", TRX = "0", PIN = "1", BB = "0", AL = "0", AAS = "0",
ADR0 = "0"
2)The S00 register cannot be written.
3)The TOF bit in the S4D0 register is set to “0” (time-out detection flag is not detected)
4)The I²C system clock (VIIC) stops counting while the internal counter and flags are reset.
16.4.3 Bit 4: Data Format Select Bit (ALS)
The ALS bit determines whether the salve address is recognized. When the ALS bit is set to “0”, an
addressing format is selected and a address data is recognized. Only if the comparison is matched
between the slave address stored into the S0D0 register and the received address data or if the
general call is received, the data is transferred. When the ALS bit is set to "1", the free data format is
selected and the slave address is not recognized.
16.4.4 Bit 6: I²C bus Interface Reset Bit (IHR)
The IHR bit is used to reset the I²C bus interface circuit when the error communication occurs.
When the ES0 bit in the S1D0 register is set to“1” (I²C bus interface is enabled), the hardware is reset
by writing “1” to the IHR bit. Flags are processed as follows:
1)The bits in the S10 register are set as MST = "0", TRX = "0", PIN to "1", BB = "0", AL = "0", AAS =
"0", and ADR0 = "0"
2)The TOF bit in the S4D0 register is set to “0” (time-out detection flag is not detected)
3)The internal counter and flags are reset.
The I²C bus interface circuit is reset after 2.5 VIIC cycles or less, and the IHR bit becomes "0" auto-
matically by writing "1" to the IHR bit. Figure 16.10 shows the reset timing.
Rev. 2.00 Jan. 31, 2007 ^{page 262} of 385
REJ09B0047-0200