MC68HC05C8A Datasheet, PDF (35/116 Pages) Motorola, Inc – Microcontrollers

Chapter 6
Low-Power Modes
6.1 Introduction
This section describes the two low-power modes — stop and wait. Figure 6-1 shows the sequence of
events caused by the STOP and WAIT instructions.
STOP
STOP OSCILLATOR
AND ALL CLOCKS
CLEAR I BIT
WAIT
OSCILLATOR ACTIVE
TIMER CLOCK ACTIVE
PROCESSOR CLOCKS STOPPED
CLEAR I BIT
N
RESET
RESET
N
EXTERNAL
Y
INTERRUPT
N
(IRQ)
Y
EXTERNAL
INTERRUPT
N
(IRQ)
Y
TURN ON OSCILLATOR
WAIT FOR TIME
DELAY TO STABILIZE
1. FETCH RESET VECTOR
OR
2. SERVICE INTERRUPT
A. STACK
B. SET I BIT
C. VECTOR TO
INTERRUPT
ROUTINE
RESTART
PROCESSOR CLOCK
1. FETCH RESET VECTOR
OR
2. SERVICE INTERRUPT
A. STACK
B. SET I BIT
C. VECTOR TO
INTERRUPT
ROUTINE
Y
Y
TIMER
INTERRUPT
N
SCI
INTERRUPT
Y
N
SPI
N
INTERRUPT
Figure 6-1. Stop/Wait Mode Flowchart
MC68HC05C8A • MC68HCL05C8A • MC68HSC05C8A Data Sheet, Rev. 5.1
Freescale Semiconductor
35