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C M L 1 2 S D P 2 5 6
MON12 OPERATION
Mon12 is an embedded monitor / debug utility that allows loading a compiled software
program (S record) into Ram memory for testing and debug. The monitor may control the
execution of the software by applying the SWI software interrupt service. Other features allow
memory and register examination or modification.
Communication with the monitor is provided on the HCS12 SCI0 serial port or COM port on
the development board. Default settings are 9600 baud with 8/n/1 bit settings. Flow control is
not provided so the host PC communication software should be set to None or Hardware flow
control. AxIDE utility software is recommended for use on a windows based host PC.
The monitor relies on resources from the HCS12 target to provide the monitor environment.
The resources include 16K bytes of flash memory and 512 bytes of internal ram memory. The
user must respect the monitor's memory map when applying the monitor to help debug code.
Restricted memory areas:
Monitor Program space: 0xC000 - 0xFFFF Flash or Flash Page $3F.
Monitor Data space:
Monitor Console:
Monitor Autostart:
Monitor application provides for redirection of interrupt vectors through the ram based
interrupt table, initialization of SCI0 serial port, initialization of HCS12 flash and EEprom
programming clock rates, initialization of 8 MHz E clock from 4Mhz reference crystal, and
detection of auto start enabled operation. The HCS12 memory map is fixed under monitor
operation.
The monitor provides for interrupt vectors in the monitor data space from 0x3F8A - 0x3FFD.
The vectors are in the same order as the default hardware table for the HCS12 located at
address 0xFF8A - 0XFFFD (see table). The Reset vector is reserved, user should apply Auto
Start for application starting from Reset.
MON12 operation notes:
1. CML12S-DP256 monitor application configures target HCS12 for 8MHz E clock, lower
flash block (page $3E) disabled from memory map, and external access clock stretch set
to 3 cycles.
User can increase clock speed in application by modifying PLL control and
setting new baud rate for serial port. Defaults will return whenever monitor is Reset.
2. Mon12 will not trace into interrupts. To trace an interrupt service set a breakpoint in the
service routine and then trace.
3. Mon12 trace is limited to expecting the next linear address. Program counter modification,
branches, calls, or subroutines will not trace correctly.
4. Monitor start-up procedure:
0x3E00 - 0x3FFF, Internal Ram.
COM Port and SCI0.
0xFEC - 0xFEF, Internal EEprom.
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0 7 / 1 7 / 0 2
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