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32182 Group User’s Manual (Rev.1.0)

CPU

2.3 Control Registers

2.3.2 Condition Bit Register: CBR (CR1)

The Condition Bit Register (CBR) is derived from the PSW register by extracting its Condition (C) bit. The value

written to the PSW register’s C bit is reflected in this register. The register can only be read. (Writing to the

After reset, the value of CBR is H’0000 0000.

b31

0000000000000000000000000000000

CBR

2.3.3 Interrupt Stack Pointer: SPI (CR2) and User Stack Pointer: SPU (CR3)

The Interrupt Stack Pointer (SPI) and the User Stack Pointer (SPU) retain the address of the current stack

pointer. These registers can be accessed as the general-purpose register R15. R15 switches between repre-

senting the SPI and SPU depending on the value of the Stack Mode (SM) bit in the PSW.

After reset, the values of the SPI and SPU are undefined.

b31

SPI

b31

SPU

2.3.4 Backup PC: BPC (CR6)

The Backup PC (BPC) is used to save the value of the Program Counter (PC) when an EIT occurs. Bit 31 is fixed

to "0".

When an EIT occurs, the register sets either the PC value when the EIT occurred or the PC value for the next

instruction depending on the type of EIT. The BPC value is loaded to the PC when the RTE instruction is

executed. However, the values of the lower 2 bits of the PC are always "00" when returned. (PC always returns

to the word-aligned address.)

After reset, the value of the BPC is undefined.

b31

BPC

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