
MC68HC908QL4  MC68HC908QL3  MC68HC908QL2 Data Sheet, Rev. 4
Freescale Semiconductor
63
Chapter 5 
Configuration Register (CONFIG)
5.1  Introduction
This section describes the configuration registers (CONFIG1 and CONFIG2). The configuration registers 
enable or disable the following options:
Stop mode recovery time (32 
× 
BUSCLKX4 cycles or 4096
 × 
BUSCLKX4 cycles)
STOP instruction
Computer operating properly module (COP)
COP reset period (COPRS): (2
13
–2
4
)
 × 
BUSCLKX4 or (2
18
–2
4
)
 × 
BUSCLKX4 
Low-voltage inhibit (LVI) enable and trip voltage selection
Auto wakeup timeout period
Allow clock source to remain enabled in STOP
Enable IRQ pin
Disable IRQ pin pullup device
Enable RST pin
5.2  Functional Description
The configuration registers are used in the initialization of various options. The configuration registers can 
be written once after each reset. Most of the configuration register bits are cleared during reset. Since the 
various options affect the operation of the microcontroller unit (MCU) it is recommended that this register 
be written immediately after reset. The configuration registers are located at $001E and $001F, and may 
be read at anytime.
NOTE
The CONFIG registers are one-time writable by the user after each reset. 
Upon a reset, the CONFIG registers default to predetermined settings as 
shown in 
Figure 5-1
 and 
Figure 5-2
.
Bit 7
6
5
4
3
2
1
Bit 0
Read:
IRQPUD
IRQEN
R
R
R
R
OSCENINSTOP
RSTEN
Write:
Reset:
0
0
0
0
0
0
0
U
POR:
0
0
0
0
0
0
0
0
R
=Reserved 
U = Unaffected 
Figure 5-1. Configuration Register 2 (CONFIG2)