![Renesas RL78/G1H Скачать руководство пользователя страница 66](http://html1.mh-extra.com/html/renesas/rl78-g1h/rl78-g1h_user-manual_1440449066.webp)
CHAPTER 4 CPU ARCHITECTURE
Page 48 of 920
4.2
Processor Registers
The RL78/G1H products incorporate the following processor registers.
4.2.1
Control registers
The control registers control the program sequence, statuses and stack memory. The control registers consist of
a program counter (PC), a program status word (PSW) and a stack pointer (SP).
(1) Program counter (PC)
The program counter is a 20-bit register that holds the address information of the next program to be
executed.
In normal operation, PC is automatically incremented according to the number of bytes of the instruction to
be fetched. When a branch instruction is executed, immediate data and register contents are set.
Reset signal generation sets the reset vector table values at addresses 0000H and 0001H to the program
counter.
Figure 4 - 6 Format of Program Counter
(2) Program status word (PSW)
The program status word is an 8-bit register consisting of various flags set/reset by instruction execution.
Program status word contents are stored in the stack area upon vectored interrupt request is acknowledged
or PUSH PSW instruction execution and are restored upon execution of the RETB, RETI and POP PSW
instructions.
Reset signal generation sets the PSW register to 06H.
Figure 4 - 7 Format of Program Status Word
(a)
Interrupt enable flag (IE)
This flag controls the interrupt request acknowledge operations of the CPU.
When 0, the IE flag is set to the interrupt disabled (DI) state, and all maskable interrupt requests are
disabled.
When 1, the IE flag is set to the interrupt enabled (EI) state and maskable interrupt requests
acknowledgment is controlled with an in-service priority flag (ISP1, ISP0), an interrupt mask flag for
various interrupt sources, and a priority specification flag.
The IE flag is reset (0) upon DI instruction execution or interrupt acknowledgment and is set (1) upon EI
instruction execution.
19
0
PC
7
0
PSW
IE
Z
RBS1
AC
RBS0
ISP1
ISP0
CY
Содержание RL78/G1H
Страница 941: ...R01UH0575EJ0120 RL78 G1H...