MC68HC908GR4 MOTOROLA [Motorola, Inc], MC68HC908GR4 Datasheet - Page 190

• Manufacturer Part Number: MC68HC908GR4
• Description: Microcontrollers
• Manufacturer: MOTOROLA [Motorola, Inc]

Monitor ROM (MON)
15.4 Functional Description
Technical Data
190
The monitor ROM receives and executes commands from a host
computer.
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
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.
1. No security feature is absolutely secure. However, Motorola’s strategy is to make reading or
copying the FLASH difficult for unauthorized users.
Freescale Semiconductor, Inc.
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For More Information On This Product,
FLASH memory security feature
FLASH memory programming interface
Enhanced PLL (phase-locked loop) option to allow use of external
32.768-kHz crystal to generate internal frequency of 2.4576 MHz
310 byte monitor ROM code size ($FE20 to $FF55)
Monitor mode entry without high voltage, V
blank ($FFFE and $FFFF contain $FF)
Standard monitor mode entry if high voltage, V
IRQ
Figure 15-1
Go to: www.freescale.com
Monitor ROM (MON)
shows an example circuit used to enter monitor
(1)
MC68HC908GR8 — Rev 4.0
TST
, if reset vector is
TST
, is applied to
MOTOROLA