PD17225_15 Datasheet, PDF (15/86 Pages) Renesas Technology Corp – 4-BIT SINGLE-CHIP MICROCONTROLLER FOR SMALL GENERAL-PURPOSE INFRARED REMOTE CONTROL TRANSMITTER

µPD17225, 17226, 17227, 17228
2.3 Stack
A stack is a register to save a program return address and the contents of system registers (to be described later) when
a subroutine is called or when an interrupt is accepted.
2.3.1 Stack configuration
Figure 2-3 shows the stack configurarion.
A stack consists of a stack pointer (a 4-bit binary counter, the high-order 1 bit fixed to 0), five 11-bit (µPD17225)/12-
bit (µPD17226)/13-bit (µPD17227, 17228) address stack registers, and three 5-bit (µPD17225, 17226)/6-bit (µPD17227,
17228) interrupt stack registers.
Figure 2-3. Stack Configuration
Stack pointer
(SP)
b3 b2 b1 b0
0 SPb2 SPb1 SPb0
WDOUT pin goes low
when the contents
of the stack pinter
are 6H-7H.
Address stack registers
(ASR)
b12 b11 b10 b9 b8 b7 b6 b5 b4 b3 b2 b1 b0
0H
Address stack register 0
1H
Address stack register 1
2H
Address stack register 2
3H
Address stack register 3
4H
Address stack register 4
5H
Undefined
6H
Undefined
7H
Undefined
µ PD17225
µPD17226
µ PD17227, 17228
Interrupt stack registers
(INTSK)
b5
b4
0H BANKSK0 BCDSK0
b3
CMPSK0
b2
CYSK0
1H BANKSK1 BCDSK1 CMPSK1 CYSK1
2H BANKSK2 BCDSK2 CMPSK2 CYSK2
b1
ZSK0
ZSK1
ZSK2
µPD17225, 17226
µ PD17227, 17228
b0
IXESK0
IXESK1
IXESK2
Data Sheet U12643EJ2V0DS00
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