MC68HC908KX8 Datasheet, PDF (260/310 Pages) Motorola, Inc – Microcontrollers

Monitor ROM (MON)
Table 18-2 shows vector differences between user mode and monitor
mode.
Table 18-2. Monitor Mode Vector Relocation
Modes
User
Monitor
Reset Vector
High
$FFFE
$FEFE
Reset Vector
Low
$FFFF
$FEFF
SWI Vector
High
$FFFC
$FEFC
SWI Vector
Low
$FFFD
$FEFD
18.7 Data Format
The MCU waits for the host to send eight security bytes
(see 18.11 Security). After the security bytes, the MCU sends a break
signal (10 consecutive logic 0s) to the host computer, indicating that it is
ready to receive a command.
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 BIT 0 BIT 1 BIT 2 BIT 3 BIT 4 BIT 5
NEXT
START
BIT 6 BIT 7 STOP BIT
BIT
Figure 18-2. Monitor Data Format
18.8 Break Signal
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
2-STOP BIT DELAY BEFORE ZERO ECHO
Technical Data
260
01234567
01234567
Figure 18-3. Break Transaction
MC68HC908KX8 • MC68HC908KX2 • MC68HC08KX8 — Rev. 1.0
Monitor ROM (MON)
MOTOROLA