Chapter 4 Operating Instructions; Introduction; Control Switch; Limitations - Motorola M68HC11EVBU User Manual

4.1

INTRODUCTION

This chapter provides the necessary information to initialize and operate the EVBU. Information
consists of the control switch description, operating limitations, command line format, monitor
commands, and operating procedures. The operating procedures consist of assembly/disassembly
and downloading descriptions and examples.
4.2

CONTROL SWITCH

Use user reset switch S1 to reset the EVBU and MCU circuits. This switch is a momentary action
pushbutton switch.
4.3

LIMITATIONS

The default baud rate for the MC68HC11 MCU SCI is 9600. using a 2 MHz E clock. You can
reset the baud rate using the memory modify (MM) command to reprogram the BAUD register in
the MCU. Or by using instructions in the user program.
The EVBU can transfer data faster than some terminal devices can receive, which at certain
times, can cause missing characters on the terminal display screen. Memory display (MD), trace
(TRACE), and help (HELP) commands may be affected by this problem. You can either ignore
the problem, switch to a slower baud rate, or use a different communications program. When
using the MD or TRACE commands, the missing character problem can be resolved by
displaying fewer address locations or tracing fewer instructions at a time, respectively.
The monitor program uses the MCU internal RAM located at $0048-$00FF. The control registers
are located at $1000-$103F. The monitor program also uses Output Compare 5 (OC5) for the
TRACE instruction, therefore TRACE cannot be used in user programs which use OC5. Since
PROCEED AND STOPAT commands indirectly use the TRACE function these commands also
rely on the OC5 to XIRQ connection via jumper header J7.
The EVBU allows you to use all the features of the BUFFALO evaluation software, however it
should be noted (when designing code) that BUFFALO uses the MCU on-chip RAM locations
$0047-$00FF leaving approximately 325 bytes for the user (i.e., $0000-$0047 and $0100-
$01FF). 512 bytes of EEPROM ($B600-B7FF) and approximately 325 bytes of RAM ($0000-
0047) + ($0100-$01FF) are available for user developed software.
M68HC11EVBU/D
CHAPTER 4
OPERATING INSTRUCTIONS
OPERATING INSTRUCTIONS
4-1