SH7144_08 Datasheet, PDF (583/930 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperHTM RISC engine Family/SH7144 Series

14. I²C Bus Interface (IIC) Option
14. Points for cautions when reading ICDR in transmit mode and writing to ICDR in receive mode
When ICDR is read in transmit mode (TRS = 1) or ICDR is written to in receive mode (TRS =
0), the SCL pin may not be held low in some cases after transmit/receive operation has been
completed, thus inconveniently allowing clock pulses to be output on the SCL bus line before
ICDR is accessed correctly. To access ICDR correctly, read the ICDR after setting to receive
mode or write to the ICDR after setting to transmit mode.
15. Points for cautions on ACKE and TRS bits in slave mode
In the I²C bus interface, if 1 is received as the acknowledge bit value (ACKB = 1) in transmit
mode (TRS = 1) and then the address is received in slave mode without performing appropriate
processing, interrupt handling may start at the rising edge of the 9th cycle of the clock even
when the address does not match.
Similarly, in slave mode, if the start condition or address is transmitted from the master device
in transmit mode (TRS = 1), the IRIC flag may be set as a result of the ICDRE flag set or
receiving 1 as the acknowledge bit value (ACKB = 1), thus causing an interrupt source to
occur even when the address does not match.
To use the I²C bus interface module in slave mode, be sure to follow the procedures below.
⎯ When 1 is received as the acknowledge bit value for the final transmit data at the end of a
series of transmit operations, clear the ACKE bit in ICCR once to initialize the ACKB bit
to 0.
⎯ Set to receive mode (TRS = 0) before the next start condition is input in slave mode.
Complete transmit operation by the procedure shown in figure 14.23, in order to switch
from slave transmit mode to slave receive mode.
14.5.1 Module Stop Mode Setting
IIC is enabled or disabled using the module stop control register. IIC is disabled with the initial
value. Cancelling module stop mode allows the register to be accessed. For details, see section 24,
Power-Down Modes.
Rev.4.00 Mar. 27, 2008 Page 539 of 882
REJ09B0108-0400