User manual

Monitor12 (MON12) User Manual 05/30/01

PROGRAM DESCRIPTION

The monitor program supplied for the EVB is called MON12. This program is

firmware based and communicates via the HC12 Serial Communications Interface

(SCI0) port. User must be aware that the monitor will initialize the hardware to

operate this port and that user programs can override proper operation of the

port to support the monitor. The monitor uses polling methods to determine port

status so interrupt operation with the SCI port would cause an interference with

the monitor.

The monitor program is contained in EPROM (external to the MCU). Having the

monitor program in EPROM external to the MCU at locations $COOO-$FFFF is a great

advantage because it allows the user to add instructions to customize the

monitor for specific requirements.

The main module of the monitor program includes all the parts required by any of

the individual command modules. Therefore the main module is a kernel of the

BUFFALO monitor program, and consists of five parts which are as follows:

a. Initialization

b. Command interpreter

c. I/O routines

d. Utility subroutines

e. Command table

INITIALIZATION

This part of the main module contains all of the reset initialization code. In

this section, internal RAM locations are set up, and the I/O channels for the

terminal is set up. The monitor will adjust the memory map of the HC12 device

for maximum use. The HC12D60 version of the monitor moves the Register space

from the Reset default address of $0000 to $0800 hex and disables the internal

Flash memories. This provides maximum user memory space in external ram memory

for debugging.

COMMAND INTERPRETER

The next section of the main module is the command interpreter. American

Standard Code for Information Interchange (ASCII) characters are read from the

terminal into the input buffer until a carriage return or a slash (/) is

received. The command field is then parsed out of the input buffer and placed

into the command buffer. A table of commands is then searched and if a match is

found, the corresponding command module is called as a subroutine. All commands

return back to the command interpreter upon completion of the operation.