ZK-HC08LX-A User's Manual
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2. The “RST_IN/RST_OUT” Connector
Introduction
All of the HC08 family devices feature a monitor code resident in ROM
which, through a serial communication line, allows the programming and
the in-circuit debugging of the user application. The monitor code is
executed in “monitor mode”; the user application is executed in “user
mode”.
To enter the monitor mode some microcontroller lines must be properly
driven. In the case of the MC68HC908LJ and LK families, these lines are
PTA0 (serial communication line), PTA1, PTA2 and PTC1.
Additionally, to enter the monitor mode, a high-level voltage signal
(VTST) must be generated on the IRQ and RST pins of the
microcontroller.
The “RST_IN#/RST_OUT#” Connector
The “RST_IN#/RST_OUT#” connector, in the “MCU” section of the
board, features the RST_IN# and RST_OUT# signals.
Depending on what in-circuit debugger/programmer you are using (built-
in USB to MON08 interface, external tool connected to the “EMON08”
connector or external tool connected to the “MON08” connector) the
RST_IN# and RST_OUT# signals assume different meanings.
Using the “EMON08” Connector
Interfacing an external in-circuit debugger/programmer via the
“EMON08” connector allows the number of wasted lines required to
enter the monitor mode and executing the monitor code to be reduced.
In addition to the RST# line, the “EMON08” connector features two
special lines, RST_IN# and RST_OUT#, which allow your target
application to be interfaced to the target microcontroller’s reset line
without worrying about the high voltage that is generated on the RST#
line.
When using the “EMON08” connector:
The RST_OUT# signal in the “RST_IN#/RST_OUT#” connector is
the reset signal generated by the external in-circuit
debugger/programmer to the target system: it can be GND or open
drain.
The RST_IN# signal is the reset signal generated by your target
application: it is adapted by the external in-circuit
debugger/programmer which properly drives the microcontroller’s
RST# line.
Using the “MON08” Connector
When using the “MON08” connector, the RST_IN# and RST_OUT#
signals in the “RST_IN#/RST_OUT#” connector coincide with the
microcontroller’s RST# signal.
Using the Built-In USB to MON08 Interface
When using the built-In USB to MON08 Interface, the RST_IN# and
RST_OUT# signals in the “RST_IN#/RST_OUT#” connector coincide
with the microcontroller’s RST# signal.
