Datasheet

Section 5 Interrupt Controller
Rev. 6.00 Mar. 18, 2010 Page 154 of 982
REJ09B0054-0600
(4) Usage Notes
The SCI and A/D converter interrupt sources are cleared when the DMAC* or DTC reads or
writes the stipulated register. This does not depend on the DTA, DTCE, and DISEL bits.
Note: * Supported only by the H8S/2239 Group.
5.6 Usage Notes
5.6.1 Contention between Interrupt Generation and Disabling
When an interrupt enable bit is cleared to 0 to disable interrupt requests, the disabling becomes
effective after execution of the instruction.
When an interrupt enable bit is cleared to 0 by an instruction such as BCLR or MOV, and if an
interrupt is generated during execution of the instruction, the interrupt concerned will still be
enabled on completion of the instruction, and so interrupt exception handling for that interrupt will
be executed on completion of the instruction. However, if there is an interrupt request of higher
priority than that interrupt, interrupt exception handling will be executed for the higher-priority
interrupt, and the lower-priority interrupt will be ignored.
The same also applies when an interrupt source flag is cleared to 0.
Figure 5.9 shows an example in which the CMIEA bit in the TCR register of the 8-bit timer is
cleared to 0.
The above contention will not occur if an enable bit or interrupt source flag is cleared to 0 while
the interrupt is masked.