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© Motorola, Inc., 2002
AN2322/D
Rev. 2, 10/2002
Reprogramming the
M68DEMO908QT4
Application Note
By: John Suchyta
Applications Engineering
8/16-Bit Products Division
Introduction
The M68DEMO908QT4 demo board was developed as a promotional tool for
the introduction of the 8-pin MC68HC908QT4 microcontroller (MCU). The
demo board consists of the MCU, an RS232 level shifter for serial
communications, a pushbutton switch and potentiometer for inputs, and an
LED for output. The board is powered by a 9 V battery and has a simple
“blinker” program and a “user monitor” program.
The 4K MCU FLASH memory can be reprogrammed through the user mode
monitor program. The user monitor program itself however cannot be
programmed or erased on the board as it was constructed. This application
note describes how to reprogram the user program space with a serial cable
through the user monitor, and how to reprogram the user monitor program
through a MON08 interface.
This application note requires that a registered version of CodeWarrior
Development Studio for 68HC08, Special Edition, version 2.1 or later, be
loaded on your PC.
Demo Board Memory Map
The M68DEMO908QT4 demo board comes with three sections of code in the
FLASH memory. The first two sections, in the 4K user array (Figure 1), contain
a “blinker” demo program and some test code. The third section, in the vector
array, contains a short “user monitor” program that is described in the
application note User Mode Monitor Access for MC68HC908QY/QT Series
MCUs, Motorola document order number AN2305/D. The user monitor is used
in the first part of this document to perform a simple debug step and to
reprogram the user FLASH with a different program. The user monitor is
invoked by holding the pushbutton switch down during power up.
CodeWarrior is a registered trademark of Metrowerks, a Motorola company.
Freescale Semiconductor, I
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