MC68HC08AZ0 Datasheet, PDF (150/444 Pages) Motorola, Inc – Advance Information

Freescale Semiconductor, Inc.
Monitor ROM (MON)
Features
Features of the monitor ROM include the following:
• 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 28.8K baud communication with host computer
• Execution of code in RAM
• EEPROM programming
Functional description
The 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.
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.
MC68HC08AZ0
148
Monitor ROM (MON)
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2-mon
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