PD17012_15 Datasheet, PDF (33/320 Pages) Renesas Technology Corp – 4-BIT SINGLE-CHIP MICROCONTROLLERS WITH DIGITAL TUNING SYSTEM HARDWARE

µPD17012, 17P012
3. ADDRESS STACK (ASK)
3.1 Outline of Address Stack
Figure 3-1 illustrates the address stack.
The address stack consists of a stack pointer and address stack registers.
The addresses of the address stack registers are specified by the stack pointer.
The address stack saves a return address when a subroutine call instruction is executed or when an interrupt
is acknowledged.
The address stack is also used when a table reference instruction is executed.
Figure 3-1. Outline of Address Stack
Stack pointer
Address specification
Address stack register
Return address
3.2 Address Stack Registers (ASR)
Figure 3-2 shows the configuration of the address stack registers.
Although there are six 12-bit address stack registers: ASR0 to ASR5, no register is assigned to ASR5, and
five 12-bit registers, ASR0 to ASR4, are used.
The address stack saves a return address when a subroutine call instruction or table reference instruction
is executed, or when an interrupt is acknowledged.
Figure 3-2. Configuration of Address Stack Registers
Stack pointer
(SP)
Bit
b3 b2 b1 b0
0 SP2 SP1 SP0
Address stack registers (ASR)
Address
Bit
b11 b10 b9 b8 b7 b6 b5 b4 b3 b2 b1 b0
0H
ASR0
1H
ASR1
2H
ASR2
3H
ASR3
4H
ASR4
5H
ASR5 (undefined)
←Cannot be used
Data Sheet U10101EJ4V0DS
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