MC68HC908GT16_07 FREESCALE [Freescale Semiconductor, Inc], MC68HC908GT16_07 Datasheet - Page 248

• Manufacturer Part Number: MC68HC908GT16_07
• Description: Microcontrollers
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

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If monitor mode was entered with V
either IRQ or RST.
This condition states that as long as V
V
then the COP will be disabled. In the latter situation, after V
removed from the IRQ pin in the interest of freeing the IRQ for normal functionality in monitor mode.
19.3.1.2 Forced Monitor Mode
If entering monitor mode without high voltage on IRQ (where applied voltage is either V
all port C pin requirements and conditions, including the PTC3 frequency divisor selection, are not in
effect. This is to reduce circuit requirements when performing in-circuit programming.
If IRQ = V
If IRQ = V
the ICGTR5 register. If the ICGTR5 register is blank, the baud rate will be a nominal 9600 baud which
may not be adequate for standard PC serial communication.
When forced monitor mode is entered, the COP is always disabled regardless of the state of IRQ or RST.
19.3.1.3 Monitor Vectors
In monitor mode, the MCU uses different vectors for reset, SWI (software interrupt), and break interrupt
than those for user mode. The alternate vectors are in the $FE page instead of the $FF page and allow
code execution from the internal monitor firmware instead of user code.
Table 19-2
248
TST
is applied to RST after the initial reset to get into monitor mode (when V
DD
SS
summarizes the differences between user mode and monitor mode.
User
Monitor
Modes
on monitor mode entry, an external oscillator of 9.8304 MHz is required for a 9600 baud rate.
on monitor mode entry, the ICG generates a 9600 baud rate using the trimmed ICG value in
If the reset vector is blank and monitor mode is entered, the chip will see an
additional reset cycle after the initial POR reset. Once the part has been
programmed, the traditional method of applying a voltage, V
must be used to enter monitor mode.
Exiting monitor mode after it has been initiated by having a blank reset
vector requires a power-on reset (POR). Pulling RST low will not exit
monitor mode in this situation.
MC68HC908GT16 • MC68HC908GT8 • MC68HC08GT16 Data Sheet, Rev. 5.0
Vector High
$FFFE
$FEFE
Reset
Vector Low
$FFFF
$FEFF
Reset
TST
Table 19-2. Mode Differences
TST
on IRQ, then the COP is disabled as long as V
is maintained on the IRQ pin after entering monitor mode, or if
Vector High
$FEFC
$FFFC
Break
NOTE
NOTE
Functions
Vector Low
TST
$FFFD
$FEFD
Break
is applied to the RST pin, V
Vector High
$FEFC
$FFFC
SWI
TST
TST
, to IRQ
was applied to IRQ),
Vector Low
Freescale Semiconductor
$FFFD
$FEFD
SWI
TST
DD
is applied to
or V
TST
SS
can be
), then