R01UH0822EJ0100 Rev.1.00
Page 49 of 1041
Jul 31, 2019
RX13T Group
2. CPU
The processor status word (PSW) indicates the results of instruction execution or the state of the CPU.
C Flag (Carry Flag)
This flag indicates whether a carry, borrow, or shift-out has occurred as the result of an operation.
Z Flag (Zero Flag)
This flag indicates that the result of an operation was 0.
S Flag (Sign Flag)
This flag indicates that the result of an operation was negative.
This flag indicates that an overflow occurred during an operation.
I Bit (Interrupt Enable)
This bit enables interrupt requests. When an exception is accepted, this bit becomes 0.
U Bit (Stack Pointer Select)
This bit specifies the stack pointer as either the ISP or USP. When an exception request is accepted, this bit becomes 0.
When the processor mode is switched from supervisor mode to user mode, this bit becomes 1.
PM Bit (Processor Mode Select)
This bit specifies the processor mode. When an exception is accepted, this bit becomes 0.
IPL[3:0] Bits (Processor Interrupt Priority Level)
The IPL[3:0] bits specify the processor interrupt priority level as one of 16 levels from zero to 15, wherein priority level
zero is the lowest and priority level 15 the highest. When the priority level of a requested interrupt is higher than the
processor interrupt priority level, the interrupt is enabled. Setting the IPL[3:0] bits to level 15 (Fh) disables all interrupt
requests. The IPL[3:0] bits are set to level 15 (Fh) when a non-maskable interrupt is generated. When interrupts are
generated, the bits are set to the priority levels of accepted interrupts.
2.2.2.5
Backup PC (BPC)
The backup PC (BPC) is provided to speed up response to interrupts.
After a fast interrupt has been generated, the contents of the program counter (PC) are saved in the BPC register.
b31
b0
Value after reset:
Undefined