MC68HC705C9A Datasheet, PDF (33/118 Pages) Motorola, Inc – Microcontrollers

Chapter 3
Central Processor Unit (CPU)
3.1 Introduction
This section contains the basic programmers model and the registers contained in the CPU.
3.2 CPU Registers
The MCU contains five registers as shown in the programming model of Figure 3-1. The interrupt stacking
order is shown in Figure 3-2.
7
7
15
PC
15
7
000000001 1
0
A
ACCUMULATOR
0
X
INDEX REGISTER
0
PROGRAM COUNTER
0
SP
STACK POINTER
CCR
H INZC
CONDITION CODE REGISTER
Figure 3-1. Programming Model
7
0 _STACK
INCREASING
MEMORY
ADDRESSES
1 1 1 CONDITION CODE REGISTER _I
R
E
T
U
R
N
ACCUMULATOR
INDEX REGISTER
PCH
N
T
E
R
R
U
P
PCL
T
DECREASING
MEMORY
ADDRESSES
UNSTACK
Figure 3-2. Interrupt Stacking Order
MC68HC05C9A Advance Information Data Sheet, Rev. 4.1
Freescale Semiconductor
33