MC68HC908KX2 MOTOROLA [Motorola, Inc], MC68HC908KX2 Datasheet - Page 256

• Manufacturer Part Number: MC68HC908KX2
• Description: Microcontrollers
• Manufacturer: MOTOROLA [Motorola, Inc]

Monitor ROM (MON)
18.3 Features
18.4 Functional Description
18.5 Monitor Mode Entry
Technical Data
256
Features of the monitor ROM include:
The monitor ROM receives and executes commands from a host
computer via a standard RS-232 interface. Simple monitor commands
can access any memory address. In monitor mode, the microcontroller
unit (MCU) can execute host-computer code in RAM while all MCU pins
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.
There are two methods for entering monitor mode. The first is the
traditional M68HC08 method where V
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
One pin dedicated to serial communication between monitor 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
FLASH memory programming interface
Monitor mode entry without high voltage, V
blank ($FFFE and $FFFF contain $FF)
Standard monitor mode entry if high voltage, V
IRQ
Monitor ROM (MON)
MC68HC908KX8 • MC68HC908KX2 • MC68HC08KX8 — Rev. 1.0
(1)
TST
is applied to IRQ1 and the
TST
, if reset vector is
TST
, is applied to
MOTOROLA