tell the debugger that the target is being aborted and the key inputs actual cause a hard
reset to take place. Because a hard reset has occurred, the code being debugged cannot
be continued, only restarted and the values of the processor’s registers will be lost.
RAM values are preserved.
Using the Debug Interface with Another Target
Another target system, which does not have its own dedicated debug interface, can be
connected to the debug section of the evaluation board. To do this, disconnect the 3
jumpers at JP3. These 3 signals are the bi-directional serial communications signal,
the reset signal and a +9v signal.
The user should read the monitor mode section of the 68HC08 manual and make the
appropriate connections for this mode. As part of entering monitor mode it is
necessary to take the processors IRQ pin to a voltage higher than VDD. If running
with a 5v target it is normal to connect IRQ to +9v. The 3 signals from the evaluation
can be connected across to the alternative target system. Make sure the any normal
connection to IRQ is disconnected or protected from damage by the +9v. Also make
sure that any reset circuit on the target does not inhibit the debug reset signal from
operating. It will also be necessary to power the evaluation board. If this is to be
powered by a battery, a common 0v connection between the evaluation board and the
alternative target will be required.
With the 3 jumpers removed, the 68HC08 on the evaluation board will, at power on,
start running from the reset vector and will execute any code programmed in its
FLASH. This can be stopped by connecting the reset pin on the evaluation board side
of JP3 to 0v.
Trouble Shooting
Problem Possible
Cause
Zap connect window keeps appearing
Board not connected or connected to
wrong COM port, Battery not connected,
wrong target selected, wrong baud rate
selected
Zap connected but security failed
message displayed
Wrong security bytes set in connect
window. Power re-cycling needed
Disassembly window or memory display
showing "adad" repeatedly
Security not passed
Processor continually resetting when
running code
COP timer not disabled