
Section 14 I2C Bus Interface (IIC)
Rev. 1.00 Mar. 02, 2006 Page 465 of 798
REJ09B0255-0100
14.5
Interrupt Sources
The IIC has interrupt source IICI. Table 14.7 shows the interrupt sources and priority. Individual
interrupt sources can be enabled or disabled using the enable bits in ICCR, and are sent to the
interrupt controller independently.
The IIC interrupts are used as on-chip DTC activation sources.
Table 14.7
IIC Interrupt Sources
Channel
Name
Enable Bit
Interrupt Source
Interrupt Flag Priority
0
IICI0
IEIC
I
2C bus interface interrupt
request
IRIC
High
1
IICI1
IEIC
I
2C bus interface interrupt
request
IRIC
2
IICI2
IEIC
I
2C bus interface interrupt
request
IRIC
Low
14.6
Usage Notes
1. In master mode, if an instruction to generate a start condition is issued and then an instruction
to generate a stop condition is issued before the start condition is output to the I
2C bus, neither
condition will be output correctly. To output the stop condition followed by the start
condition*, after issuing the instruction that generates the start condition, read DR in each I
2C
bus output pin, and check that SCL and SDA are both low. The pin states can be monitored by
reading DR even if the ICE bit is set to 1. Then issue the instruction that generates the stop
condition. Note that SCL may not yet have gone low when BBSY is cleared to 0.
Note: * An illegal procedure in the I
2C bus specification.
2. Either of the following two conditions will start the next transfer. Pay attention to these
conditions when accessing to ICDR.
Write to ICDR when ICE = 1 and TRS = 1 (including automatic transfer from ICDRT to
ICDRS)
Read from ICDR when ICE = 1 and TRS = 0 (including automatic transfer from ICDRS to
ICDRR)
3. Table 14.8 shows the timing of SCL and SDA outputs in synchronization with the internal
clock. Timings on the bus are determined by the rise and fall times of signals affected by the
bus load capacitance, series resistance, and parallel resistance.