MC68HC08AZ32A Datasheet, PDF (156/456 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
Monitor ROM (MON)
• Execution of Code in RAM or ROM
• EEPROM Programming
• ROM Security (Read Protection)⁽¹⁾
• EEPROM Read Protection⁽¹⁾
11.4 Functional description
The monitor ROM receives and executes commands from a host
computer. Figure 11-1 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
MC68HC08AZ32A has optional ROM/EEPROM read protection
features to prevent external viewing of the contents of ROM/EEPROM
(see Mask Options on page 145). Proper procedures must be followed
to verify ROM/EEPROM content. Access to the ROM/EEPROM is
denied to unauthorized users of customer specified software with read
protection features enabled. See Security on page 164.
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 pull-up resistor.
Technical Data
156
1. No security feature is absolutely secure. However, Motorola’s strategy is to make reading or
copying the ROM/EEPROM data difficult for unauthorized users
MC68HC08AZ32A — Rev 1.0
Monitor ROM (MON)
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