Hardware and Software Development Tools for the HCS12 - The HCS12/9S12: An Introduction to Software and Hardware Interfacing - page 140

The BDM pod can be connected to the PC or workstation via the serial, parallel, or USB
port. There must be a software program running on the PC or workstation to send commands
to the POD to perform the appropriate debug operations. This PC-based software should have a
good user interface and allow the user to perform at least the following operations:
• Do basic configuration
• Download the program to the target board for execution
• Set breakpoints
• Display and change the values of the CPU registers, I/O registers, and memory
locations
• Display the source code
• Set up a watch list to display the values of selected program variables
• Trace the program execution to the breakpoint
The PC sends the intended operation of the user to the POD and the POD sends the corre-
sponding BDM commands to the target board to perform the desired operations. A source-level
debugger using this approach need not be expensive. A BDM-based source-level debugger can be
integrated with an IDE, which allows the user to perform program editing, assembling or compil-
ing, and source-level debugging in the same environment. CodeWarrior supports the BDM-based
debug adapters from several vendors. The BDM pod can also be part of the target board.
3.11 Summary
The HCS12 microcontroller was developed as an upgrade for the 8-bit 68HC11 microcon-
troller family. All members implement the same architecture; that is, they have the same in-
struction set and addressing modes, but differ in the number of peripheral functions that they
implement.
All HCS12 members use the same design in each peripheral function; this simplifies the
migration from one device to another. All of the HCS12 members implement a 10-bit A/D con-
verter. The HCS12 microcontroller implements a complicated timer system.
• The input-capture (IC) function latches the arrival time of a signal edge. This
capability allows the user to measure the frequency, the period, and the duty cycle
of an unknown signal.
• The output compare (OC) function allows the user to make a copy of the main
timer, add a delay to this copy, and store the sum to an output compare register.
This capability can be used to create a delay, generate a digital waveform, trigger an
action on a signal pin, and so on.
• The pulse accumulation function allows one to count the events that arrived
within an interval.
• The pulse-width modulation (PWM) module is used to generate a digital waveform
of a certain frequency with a duty cycle ranging from 0 to 100 percent. This
capability is useful in DC motor control.
The HCS12 microcontroller also provides a wide variety of serial interface functions to ap-
peal to different applications.