Section 5 Interrupt Controller
Rev. 1.00 Mar. 12, 2008 Page 102 of 1178
REJ09B0403-0100
5.7 Usage
Notes
5.7.1
Conflict 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, 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 rule is also applied when an interrupt source flag is cleared to 0. Figure 5.9
shows an example in which the CMIEA bit in the TMR's TCR register is cleared to 0.
The above conflict will not occur if an enable bit or interrupt source flag is cleared to 0 while the
interrupt is masked.
Internal
address bus
Internal
write signal
φ
CMIEA
CMFA
CMIA
interrupt signal
TCR write cycle
by CPU
CMIA exception handling
TCR address
Figure 5.9 Conflict between Interrupt Generation and Disabling
Summary of Contents for H8S Family
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Page 108: ...Section 2 CPU Rev 1 00 Mar 12 2008 Page 60 of 1178 REJ09B0403 0100...
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Page 152: ...Section 5 Interrupt Controller Rev 1 00 Mar 12 2008 Page 104 of 1178 REJ09B0403 0100...
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Page 420: ...Section 9 14 Bit PWM Timer PWMX Rev 1 00 Mar 12 2008 Page 372 of 1178 REJ09B0403 0100...
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Page 552: ...Section 14 CRC Operation Circuit CRC Rev 1 00 Mar 12 2008 Page 504 of 1178 REJ09B0403 0100...
Page 712: ...Section 18 I2 C Bus Interface IIC Rev 1 00 Mar 12 2008 Page 664 of 1178 REJ09B0403 0100...
Page 804: ...Section 19 LPC Interface LPC Rev 1 00 Mar 12 2008 Page 756 of 1178 REJ09B0403 0100...
Page 838: ...Section 20 Ethernet Controller EtherC Rev 1 00 Mar 12 2008 Page 790 of 1178 REJ09B0403 0100...
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Page 1066: ...Section 25 Flash Memory Rev 1 00 Mar 12 2008 Page 1018 of 1178 REJ09B0403 0100...
Page 1098: ...Section 26 Boundary Scan JTAG Rev 1 00 Mar 12 2008 Page 1050 of 1178 REJ09B0403 0100...
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