MC68HC908BD48 Datasheet, PDF (119/290 Pages) Freescale Semiconductor, Inc – Microcontrollers

Monitor ROM (MON)
Functional Description
Alternatively, the host can send a RUN command, which executes an
RTI, and this can be used to send control to the address on the stack
pointer.
The COP module is disabled in monitor mode as long as V_TST is applied
to the IRQ or the RST pin. (See Section 7. System Integration Module
(SIM) for more information on modes of operation.)
Table 9-2 is a summary of the differences between user mode and
monitor mode.
Table 9-2. Mode Differences
Functions
Modes
COP
Reset
Vector
High
Reset
Vector
Low
SWI
Vector
High
SWI
Vector
Low
User
Enabled
$FFFE
$FFFF
$FFFC
$FFFD
Monitor
Disabled⁽¹⁾
$FEFE
$FEFF
$FEFC
$FEFD
Notes:
1. If the high voltage (V_TST) is removed from the IRQ pin, the SIM asserts its COP enable
output. The COP is a mask option enabled or disabled by the COPD bit in the configuration
register.
9.4.2 Data Format
Communication with the monitor ROM is in standard non-return-to-zero
(NRZ) mark/space data format. (See Figure 9-2 and Figure 9-3.)
NEXT
START
START
BIT BIT 0 BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7 ^STOP BIT
BIT
Figure 9-2. Monitor Data Format
NEXT
START
START
$A5 _BIT BIT 0 BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7 STOP BIT
BIT
START
STOP
BREAK _BIT BIT 0 BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7 BIT
Figure 9-3. Sample Monitor Waveforms
MC68HC908BD48 — Rev. 1.0
MOTOROLA
Monitor ROM (MON)
Technical Data
119