AN2548 Freescale Semiconductor / Motorola, AN2548 Datasheet - Page 3

• Manufacturer Part Number: AN2548
• Description: Serial Monitor Program for HCS12 MCUs
• Manufacturer: Freescale Semiconductor / Motorola

Memory Configuration
Serial Port Usage
MOTOROLA
If the user application uses the COP, two issues must be considered:
The monitor as written is intended to work with all HCS12 Family members
available at the time of publication. Adding a new device requires creating a few
memory definitions for the new device. The memory definition is stored in the
S12SerMonxrx.def file. EB386/D should be studied for complete understanding
of the theory behind the memory configuration chosen. A short description is
given below:
For the serial port function of the monitor to work, the SCI0 serial interface is
used. The monitor must have exclusive use of this interface. User application
code should not implement communications on this serial channel.
This monitor accommodates RS-232 serial communications through SCI0 at
115.2 kbaud. For systems requiring the use of SCI0, use a BDM development
system that allows more sophisticated debugging. Alternatively, this monitor
program may be modified by the user to check the state of the switches used
to enter the monitor and adjust vector relocation accordingly. This modification
would enable the user to use the monitor SCI port, although debugging of SCI0
routines would be very difficult or impossible using the monitor.
During initialization after any cold reset, a long break is transmitted before any
other SCI communication takes place. This break is about 30 bit-times to
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If the COP is disabled in the user application, the monitor will be unable
to perform a hard reset and will soft reset to the start of the monitor
instead.
The monitor does not service the COP timer. If the user application
implements COP timer servicing, upon re-entry into the monitor, a hard
reset is likely to occur.
Register space is located at $0000–$03FF.
FLASH memory is any address greater than $4000. All paged
addresses are assumed to be FLASH memory.
RAM ends at $3FFF and builds down to the limit of the device’s available
RAM.
EEPROM (if the target device has any) is limited to the available space
between the registers and the RAM ($0400–to start of RAM).
External devices attached to the multiplexed external bus interface are
not supported.
Serial Monitor Program for HCS12 MCUs
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Memory Configuration
AN2548/D
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