47
3886 Group
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
MITSUBISHI MICROCOMPUTERS
[I
2
C START/STOP Condition Control Register
(S2D)] 0017
16
The I
2
C START/STOP condition control register (address 0017
16
)
controls START/STOP condition detection.
Bits 0 to 4: START/STOP condition set bit (SSC4–SSC0)
S
CL
release time, setup time, and hold time change the detection
condition by value of the main clock divide ratio selection bit and
the oscillation frequency f(X
IN
) because these time are measured
by the internal system clock. Accordingly, set the proper value to
the START/STOP condition set bits (SSC4 to SSC0) in considered
of the system clock frequency. Refer to Table 13.
Do not set “00000
2
” or an odd number to the START/STOP condi-
tion set bit (SSC4 to SSC0).
Refer to Table 14, the recommended set value to START/STOP
condition set bits (SSC4–SSC0) for each oscillation frequency.
Bit 5: S
CL
/S
DA
interrupt pin polarity selection bit (SIP)
An interrupt can occur when detecting the falling or rising edge of
the S
CL
or S
DA
pin. This bit selects the polarity of the S
CL
or S
DA
pin interrupt pin.
Bit 6: S
CL
/S
DA
interrupt pin selection bit (SIS)
This bit selects the pin of which interrupt becomes valid between
the S
CL
pin and the S
DA
pin.
Note:
When changing the setting of the S
CL
/S
DA
interrupt pin polarity se-
lection bit, the S
CL
/S
DA
interrupt pin selection bit, or the I
2
C-BUS
interface enable bit ES0, the S
CL
/S
DA
interrupt request bit may be
set. When selecting the S
CL
/S
DA
interrupt source, disable the inter-
rupt before the S
CL
/S
DA
interrupt pin polarity selection bit, the S
CL
/
S
DA
interrupt pin selection bit, or the I
2
C-BUS interface enable bit
ES0 is set. Reset the request bit to “0” after setting these bits, and
enable the interrupt.
Bit 7: START/STOP condition generating selection bit
(STSPSEL)
Setup/Hold time when the START/STOP condition is generated
can be selected.
Cycle number of system clock becomes standard for setup/hold
time. Additionally, setup/hold time is different between the START
condition and the STP condition. (Refer to Tables 11 and 12.) Set
“1” to this bit when the system clock frequency is 4 MHz or more.
Address Data Communication
There are two address data communication formats, namely, 7-bit
addressing format and 10-bit addressing format. The respective
address communication formats are described below.
7-bit addressing format
To adapt the 7-bit addressing format, set the 10BIT SAD bit of
the I
2
C control register (address 0015
16
) to “0.” The first 7-bit
address data transmitted from the master is compared with the
high-order 7-bit slave address stored in the I
2
C address register
(address 0013
16
). At the time of this comparison, address com-
parison of the RBW bit of the I
2
C address register (address
0013
16
) is not performed. For the data transmission format
when the 7-bit addressing format is selected, refer to Figure 46,
(1) and (2).
10-bit addressing format
To adapt the 10-bit addressing format, set the 10BIT SAD bit of
the I
2
C control register (address 0015
16
) to “1.” An address
comparison is performed between the first-byte address data
transmitted from the master and the 8-bit slave address stored
in the I
2
C address register (address 0013
16
). At the time of this
comparison, an address comparison between the RBW bit of
the I
2
C address register (address 0013
16
) and the R/W bit
which is the last bit of the address data transmitted from the
master is made. In the 10-bit addressing mode, the RBW bit
which is the last bit of the address data not only specifies the
direction of communication for control data, but also is pro-
cessed as an address data bit.
When the first-byte address data agree with the slave address,
the AAS bit of the I
2
C status register (address 0014
16
) is set to
“1.” After the second-byte address data is stored into the I
2
C
data shift register (address 0012
16
), perform an address com-
parison between the second-byte data and the slave address
by software. When the address data of the 2 bytes agree with
the slave address, set the RBW bit of the I
2
C address register
(address 0013
16
) to “1” by software. This processing can make
the 7-bit slave address and R/W data agree, which are re-
ceived after a RESTART condition is detected, with the value of
the I
2
C address register (address 0013
16
). For the data trans-
mission format when the 10-bit addressing format is selected,
refer to Figure 46, (3) and (4).