3803_03 Datasheet, PDF (71/136 Pages) Renesas Technology Corp – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

3803/3804 Group
[I²C Data Shift Register (S0)] 001116
The I²C data shift register (S0: address 001116) is an 8-bit shift
register to store receive data and write transmit data.
When transmit data is written into this register, it is transferred to
the outside from bit 7 in synchronization with the SCL, and each
time one-bit data is output, the data of this register are shifted by
one bit to the left. When data is received, it is input to this register
from bit 0 in synchronization with the SCL, and each time one-bit
data is input, the data of this register are shifted by one bit to the
left. The minimum 2 cycles of the internal clock φ are required
from the rising of the SCL until input to this register.
The I²C data shift register is in a write enable status only when the
I²C-BUS interface enable bit (ES0 bit) of the I²C control register
(S1D: address 001416) is “1”. The bit counter is reset by a write in-
struction to the I²C data shift register. When both the ES0 bit and
the MST bit of the I²C status register (S1: address 001316) are “1,”
the SCL is output by a write instruction to the I²C data shift regis-
ter. Reading data from the I²C data shift register is always enabled
regardless of the ES0 bit value.
[I²C Slave Address Registers 0 to 2 (S0D0 to S0D2)]
0FF716 to 0FF916
The I²C slave address registers 0 to 2 (S0D0 to S0D2: addresses
0FF716 to 0FF916) consists of a 7-bit slave address and a read/
write bit. In the addressing mode, the slave address written in this
register is compared with the address data to be received immedi-
ately after the START condition is detected.
•Bit 0: Read/write bit (RWB)
This is not used in the 7-bit addressing mode. In the 10-bit ad-
dressing mode, set RWB to “0” because the first address data to
be received is compared with the contents (SAD6 to SAD0 +
RWB) of the I²C slave address registers 0 to 2.
When 2-byte address data match slave address, a 7-bit slave ad-
dress which is received after restart condition has detected and
R/W data can be matched by setting “1” to RWB with software.
The RWB is cleared to “0” automatically when the stop condition is
detected.
•Bits 1 to 7: Slave address (SAD0–SAD6)
These bits store slave addresses. Regardless of the 7-bit address-
ing mode or the 10-bit addressing mode, the address data
transmitted from the master is compared with these bits’ contents.
b7
b0
I²C slave address register 0
SAD6 SAD5 SAD4 SAD3 SAD2 SAD1 SAD0 RWB _{(S0D0: address 0FF716)}
I²C slave address register 1
(S0D1: address 0FF816)
I²C slave address register 2
(S0D2: address 0FF916)
Read/write bit
Slave address
Fig. 65 Structure of I²C slave address registers 0 to 2
Rev.4.01 Nov 14, 2003 page 71 of 136