Limitations - Motorola M68705EVM User Manual

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3.3 LIMITATIONS
The MC6805R2 MCU timer is not software controllable.(see paragraph 2.3.1 ).
The resident MC6805R2 MCU timer is stopped when the monitor is invoked. When the
MC68705R3 is installed as the resident MCU, the timer is software controllable and the timer
stop feature is lost.
The user may not trace a return from interrupt (RTI) or a clear interrupt mask bit (CLI)
instruction with an interrupt enabled and pending due to MCU interrupt handling. Attempting
this will cause multiple interrupts in the user map. User breakpoints will be left in the user
map, but will not be recognized by the monitor. The user stack pointer will also reflect the
occurance of multiple interrupts.
Mixing interrupt requests (IRQs) and user software interrupts (SWls) should be avoided
whenever possible, due to IRQ-SWI EVM timing. If a concurrent hardware interrupt and SWI
should happen, an EVM failure could occur which may stop program execution. Activation of
the MASTER RESET switch will restore the EVM to proper operation. These conditions will
statistically occur very seldom.
No protection is provided to limit user programs to the exact amount of MCU ROM/EPROM
available. The user must be aware of the memory map of the MCU being simulated and
ensure that only valid ROM/EPROM locations are used.
The baud rates of the terminal and host 1/0 ports are independent; however, during
transparent mode, characters from the host computer to the terminal may occasionally be lost
if the terminal baud rate is not higher than the host baud rate. This occurs only during the
transparent mode, and does not apply when downloading to memory.
EVALUATION MODULE USER'S MANUAL
3-4
MOTOROLA
M68705EVM