MC68HC05C9E Datasheet, PDF (23/106 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 3
Central Processor Unit (CPU)
3.1 Introduction
This section contains information describing the basic programmer’s model and the registers contained
in the central processor unit (CPU).
3.2 CPU Registers
The microcontroller unit (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
A
0
ACCUMULATOR
7
X
0
INDEX REGISTER
13
PC
13
7
0000001 1
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
UNSTACK
Figure 3-2. Interrupt Stacking Order
DECREASING
MEMORY
ADDRESSES
MC68HC05C9E Advance Information Data Sheet, Rev. 0.1
Freescale Semiconductor
23