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M5253EVBE Users Manual, Rev. 1
2-4
Freescale Semiconductor
If you did not get this response check the setup, refer to
Section 1.7, “System Power-up and Initial
Operation
.”
Other means can be used to re-initialize the M5253EVBE firmware. These means are discussed in
Section 2.2.2.1, “Hard RESET Button
,”
Section 2.2.2.2, “ABORT Button
,” and
Section 2.2.2.3,
“Software Reset Command
.”
2.2.2.1
Hard RESET Button
Hard RESET (S1) is the red button. Pressing this button causes all processes to terminate, resets the
MCF5253 processor and board logic, and restarts the dBUG firmware. Pressing the RESET button would
be the appropriate action if all else fails.
2.2.2.2
ABORT Button
ABORT (S2) is the button located next to the RESET button. The abort function causes an interrupt of the
present processing (a level 7 interrupt on MCF5253) and gives control to the dBUG firmware. This action
differs from RESET in that no processor register or memory contents are changed, the processor and
peripherals are not reset, and dBUG is not restarted. Also, in response to depressing the ABORT button,
the contents of the MCF5253 core internal registers are displayed.
The abort function is most appropriate when software is being debugged. The user can interrupt the
processor without destroying the present state of the system. This is accomplished by forcing a
non-maskable interrupt that will call a dBUG routine that will save the current state of the registers to
shadow registers in the monitor for display to the user. The user will be returned to the ROM monitor
prompt after exception handling.
2.2.2.3
Software Reset Command
dBUG’s command—“RESET”—causes the dBUG to restart as if a hardware reset was invoked.
2.3
Command Line Usage
The user interface to dBUG is the command line. A number of features have been implemented to achieve
an easy and intuitive command line interface.
dBUG assumes that an 80 x 24 ASCII-character dumb terminal is used to connect to the debugger. For
serial communications, dBUG requires eight data bits, no parity, and one stop bit (8N1). The baud rate
default is 115200 bps—a speed commonly available from workstations, personal computers, and
dedicated terminals.
The command line prompt is: dBUG>
Any dBUG command may be entered from this prompt. dBUG does not allow command lines to exceed
80 characters. Wherever possible, dBUG displays data in 80 columns or fewer. dBUG echoes each
character as it is typed, eliminating the need for any local echo on the terminal side.
The <Backspace> and <Delete> keys are recognized as rub-out keys for correcting typographical
mistakes.