R5F21388SNFP Datasheet, PDF (17/63 Pages) Renesas Technology Corp – RENESAS MCU

R8C/38T-A Group
2. Central Processing Unit (CPU)
2.8.7 Interrupt Enable Flag (I)
The I flag enables maskable interrupts. Interrupts are disabled when the I flag is 0, and are enabled when the I
flag is 1. The I flag is set to 0 when an interrupt request is acknowledged.
2.8.8 Stack Pointer Select Flag (U)
ISP is selected when the U flag is 0. USP is selected when the U flag is 1. The U flag is set to 0 when a hardware
interrupt request is acknowledged or the INT instruction for a software interrupt numbered from 0 to 31 is
executed.
2.8.9 Processor Interrupt Priority Level (IPL)
IPL is 3 bits wide and assigns eight processor interrupt priority levels from 0 to 7. If a requested interrupt has
higher priority than IPL, the interrupt is enabled.
2.8.10 Reserved Bit
The write value must be 0. The read value is undefined.
R01DS0081EJ0100 Rev.1.00
Dec 09, 2011
Page 17 of 60