MC68HC908QY2 MOTOROLA [Motorola, Inc], MC68HC908QY2 Datasheet - Page 114

• Manufacturer Part Number: MC68HC908QY2
• Description: Microcontrollers
• Manufacturer: MOTOROLA [Motorola, Inc]

Monitor ROM (MON)
9.3 Features
9.4 Functional Description
114
MC68HC908QY4•MC68HC908QT4•MC68HC908QY2•MC68HC908QT2•MC68HC908QY1•MC68HC908QT1
Features of the monitor ROM include:
The monitor ROM receives and executes commands from a host
computer.
used to enter monitor mode and communicate with a host computer via
a standard RS-232 interface.
Simple monitor commands can access any memory address. In monitor
mode, the MCU can execute code downloaded into RAM by a host
computer while most MCU pins retain normal operating mode functions.
All communication between the host computer and the MCU is through
1. No security feature is absolutely secure. However, Motorola’s strategy is to make reading or
copying the FLASH difficult for unauthorized users.
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Normal user-mode pin functionality on most pins
One pin dedicated to serial communication between monitor
read-only memory (ROM) and host computer
Standard mark/space non-return-to-zero (NRZ) communication
with host computer
Execution of code in random-access memory (RAM) or FLASH
FLASH memory security feature
FLASH memory programming interface
Use of external 9.83 MHz crystal or clock to generate internal
frequency of 2.4576 MHz
Simple internal oscillator mode of operation (no external clock or
high voltage)
574 bytes monitor ROM code size
Monitor mode entry without high voltage, V
blank ($FFFE and $FFFF contain $FF)
Standard monitor mode entry if high voltage is applied to IRQ
Figure
Monitor ROM (MON)
9-1,
Figure
9-2, and
Figure 9-3
(1)
TST
show example circuits
, if reset vector is
MOTOROLA