M32C8A Datasheet, PDF (357/372 Pages) Renesas Technology Corp – RENESAS MCU M16C FAMILY / M32C/80 Series

M32C/8A Group
24. Usage Notes
24.5.4 Changing Interrupt Control Register
To change the Interrupt Control Register while an interrupt request is disabled, use the following instructions.
Changing IR bit:
The IR bit may not be changed to 0 (interrupt not requested) by writing, depending on which instruction is used.
If this causes a problem, use MOV instruction to change the register. (Technical update: TN-M16C-85-0204)
Changing any bits other than IR bit:
If an interrupt request is generated while writing to the corresponding Interrupt Control Register with
instructions such as MOV, the IR bit may not become 1 (interrupt requested) and the interrupt is not
acknowledged. If this causes a problem, use the following instructions to write to the register:
AND, OR, BCLR, BSET
24.5.5 Changing RLVL Register
The DMAII bit in the RLVL register is undefined after reset. To use interrupt priority level 7 for an interrupt,
set it to 0 before setting the Interrupt Control Register.
Rev.1.00 Jul 15, 2007 Page 340 of 352
REJ09B0385-0100