MC68HC08AZ60 Datasheet, PDF (142/452 Pages) Motorola, Inc – Advance Information

Freescale Semiconductor, Inc.
Monitor ROM (MON)
Features
Features of the monitor ROM include:
• Normal User-Mode Pin Functionality
• One Pin Dedicated to Serial Communication between Monitor
ROM and Host Computer
• Standard Mark/Space Non-Return-to-Zero (NRZ) Communication
with Host Computer
• Up to 28.8 kBaud Communication with Host Computer
• Execution of Code in RAM.
Functional Description
Monitor ROM receives and executes commands from a host computer.
Figure 1 shows a sample circuit used to enter monitor mode and
communicate with a host computer via a standard RS-232 interface.
While simple monitor commands can access any memory address, the
MC68HC08AZ60 has a ROM security feature to prevent external
viewing of the contents of ROM. Proper procedures must be followed to
verify ROM content. Access to the ROM is denied to unauthorized users
of customer specified software (see Security on page 151).
In monitor mode, the MCU can execute host-computer code in RAM
while all MCU pins except PTA0 retain normal operating mode functions.
All communication between the host computer and the MCU is through
the PTA0 pin. A level-shifting and multiplexing interface is required
between PTA0 and the host computer. PTA0 is used in a wired-OR
configuration and requires a pullup resistor.
MC68HC08AZ60 — Rev 1.0
142
Monitor ROM (MON)
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2-mon
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