Freescale Semiconductor, Inc.
Monitor ROM (MON)
Functional Description
Table 13-2 is a summary of the differences between user mode and
monitor mode.
Table 13-2. Mode Differences
Functions
Modes
Reset
Vector Vector Vector Vector Vector Vector
High Low High Low High Low
Reset
Break
Break
SWI
SWI
COP
User
Enabled
$FFFE $FFFF $FFFC $FFFD $FFFC $FFFD
$FEFE $FEFF $FEFC $FEFD $FEFC $FEFD
(1)
Monitor
Disabled
1. If the high voltage (VHI) is removed from the IRQ pin while in monitor mode, the SIM asserts
its COP enable output. The COP is a mask option enabled or disabled by the COPD bit in
the configuration register. See 24.5 5.0 Volt DC Electrical Characteristics.
13.4.2 Data Format
Communication with the MON is in standard non-return-to-zero (NRZ)
mark/space data format. (See Figure 13-2 and Figure 13-3.)
The data transmit and receive rate can be anywhere from 4800 baud to
28.8 Kbaud. Transmit and receive baud rates must be identical.
NEXT
START
BIT
START
BIT
STOP
BIT
BIT 0
BIT 1
BIT 2
BIT 3
BIT 4
BIT 5
BIT 6
BIT 7
Figure 13-2. Monitor Data Format
NEXT
START
BIT
START
STOP
$A5
BIT 0
BIT 0
BIT 1
BIT 2
BIT 2
BIT 3
BIT 3
BIT 4
BIT 4
BIT 5
BIT 5
BIT 6
BIT 6
BIT 7
BIT 7
BIT
BIT
STOP
BIT
START
BIT
NEXT
START
BIT
BREAK
BIT 1
Figure 13-3. Sample Monitor Waveforms
MC68HC908AS60 — Rev. 1.0
Technical Data
Monitor ROM (MON)
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