16 Freescale Semiconductor
Development Studio and other serial monitor interface IDE’s. The serial monitor is not
compatible with ASCII interface programs such as HyperTerm or AxIDE. The monitor supports
23 primitive commands to control the target MCU. To allow a user to specify the address of
each interrupt service routine, this monitor redirects interrupt vectors to an unprotected portion
of FLASH.
To boot to the serial monitor, the user simply pressed and holds SW1 while pressing the
RESET switch or applying power. The status of SW1 is read only during the rising edge of
RESET. To load user application on start-up, the user is responsible for programming the
pseudo-reset vector (0xF7FE:0xF7FF). Pressing SW1 after the MCU exits reset will not
access the serial monitor. After exiting reset, pressing SW1 has effect as defined in the user
application.
BDM_PORT Header
BDM access is gained through the BDM_PORT header. This is a 6-pin header that allows
connection of a compatible HCS12 BDM cable. Refer to the documentation for the specific
BDM cable used for details on its use. The figure below shows the pin-out for the DEBUG
header.
Figure 4: BDM_PORT
MODC/BKGD
1
2
GND
3
4
RESET*
5
6
VDD
See the HC12 Reference Manual for complete
DEBUG documentation
