Data Format - Motorola MC68HC908GP32 Technical Data Manual

Monitor ROM (MON)

15.4.2 Data Format

15.4.3 Break Signal
Technical Data
202
Freescale Semiconductor, Inc.
Table 15-2 summarizes the differences between user mode and monitor
mode.
Table 15-2. Mode Differences
Modes Reset
Vector
High
User $FFFE
Monitor $FEFE
Communication with the monitor ROM is in standard non-return-to-zero
(NRZ) mark/space data format. Transmit and receive baud rates must
be identical.
START
BIT 0 BIT 1 BIT 2
BIT
Figure 15-3. Monitor Data Format
A start bit (logic 0) followed by nine logic 0 bits is a break signal. When
the monitor receives a break signal, it drives the PTA0 pin high for the
duration of two bits and then echoes back the break signal.
MISSING STOP BIT
0 1 2 3 4
Figure 15-4. Break Transaction
Monitor ROM (MON)
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Functions
Reset Break
Vector Vector
Low High
$FFFF $FFFC
$FEFF $FEFC
BIT 6
BIT 3 BIT 4 BIT 5
2-STOP BIT DELAY BEFORE ZERO ECHO
0
5 6 7
MC68HC908GP32
Break SWI SWI
Vector Vector Vector
Low High Low
$FFFD $FFFC $FFFD
$FEFD $FEFC $FEFD
NEXT
START
STOP
BIT 7 BIT
BIT
1 2 3 4 5 6 7
MC68HC08GP32 Rev. 6
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