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M16C/28 Group
Under development Preliminary specification
Specifications in this manual are tentative and subject to change.
16. MULTI-MASTER I2C bus INTERFACE
Rev.0.60 2004.02.01
page 259 of N
REJ09B0047-0060Z
16.8 I2C0 START/STOP condition control registers (S2D0 register)
The I2C0 START/STOP condition control register(address 02E516) controls the detection of the START/
STOP condition.
16.8.1 Bit0-Bit4: START/STOP condition setting bits (SSC0-SSC4)
Because the release time, the set up time and the hold time of the SCL are measured on the base of the I2C
bus system clock(VIIC). The detecting condition changes depending on the oscillation frequency (XIN) and
the I2C bus system clock select bits. It is necessary to set the appropriate value of START/STOP condition
setting bits (SSC4-SSC0) and set the release time, the set up time and the hold time by the system clock
frequency. Refer to Table 16.10 Start/Stop condition detect conditions. Do not set odd numbers or
“000002” to START/STOP condition setting bits. Table 16.2 shows the recommended setting value to START/
STOP condition setting bits (SSC4-SSC0) at each oscillation frequency under standard clock mode. The
detection of the START/STOP condition starts immediately after setting the ES0 bit to "1".
16.8.2 Bit5: SCL/SDA interrupt pin polarity select bit (SIP)
The SCL/SDA interrupt can be generated by detecting the rising edge or the falling edge of the SCL pin or
the SDA pin. The SCL/SDA interrupt pin polarity select bit selects the polarity of the SCL pin or the SDA pin for
interrupt.
16.8.3 Bit6 : SCL/SDA interrupt pin select bit (SIS)
The SCL/SDA interrupt pin select bit selects either the SCL pin or the SDA pin as the SCL/SDA interrupt enable
pin.
NOTES:
The SCL/SDA interrupt request may be set when the setting of the SCL/SDA interrupt pin polarity se lect
bit, SCL/SDA interrupt pin select bit and I2C bus interface enable bit ES0 are changed. When using the
SCL/SDA interrupt, write “0” to the SCL/SDA interrupt request bit after setting the above bits, and enable
the SCL/SDA interrupt.
16.8.4 Bit7: START/STOP condition generation select bit (STSPSEL)
The bit selects the length of the set up and the hold time when the START/STOP condition is generated. The
length of the set up and hold time is based on the I2C system clock cycles. Refer to Table 16.8 Start/Stop
generation timing table. Set the bit to “1” if the I2C bus system clock frequency is over 4MHz.