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APPENDIX A – TECHNICAL REFERENCE & TROUBLESHOOTING
9. Make sure the host PC can communicate with the MCU:
A-10
a. The MCU's PTA0 pin is used for host communications. DDRA bit 0
should never be set to 1, as this interrupts monitor-mode communi-
cations. The MON08 pin TGT_PTA0 (J3 pin 9) is never connected
to the MCU's PTA0 pin. It is wired to XU1 pin 30 for probing pur-
poses. On the MON08 connector J3, pin 10 is wired to the MCU's
PTA0 pin. Driving this signal with external logic on the target sys-
tem will interrupt communications.
b. Make sure that the MON08 cable is properly installed between the
ICS08AB and the target system. Pin 1 of each connector on the
cable must go to pin 1 of the headers on the ICS08AB and target
system.
c. Make sure that the serial cable is correctly attached to the ICS08AB
and to the correct serial port on the host computer.
d. Make sure that the cable is a straight-through cable supporting all
nine pins of the serial-port connection.
e. Make sure that no hardware security key or other device is attached
to the serial port or cable.
f. Make sure that the host PC supports the minimum speed require-
ments of the ICS08ABZ software.
g. Make sure to use the correct security code to access the MCU. If
you have previously programmed the security bytes, the part will
not unlock and enter monitor mode unless the correct security code
is sent to the MCU.
h. Make sure the serial data is getting to the MCU's PTA0 pin. Re-
start the ICS08ABZ simulator software as described in sections 3
and 4 of the quick-start instructions. Probe the PTA0 pin of the tar-
get MCU for the serial data. Since the board power is turned off and
on several times during the connecting phase, the data observed at
the MCU's PTA0 pin is also affected.
i. Make sure that the target MCU has a good clock source. Use a
clock rate that gives a 9600-baud serial communications rate for
monitor mode on the target system. Use an oscilloscope to check
the OSC2 output at the MCU. Set the oscilloscope to 0.1 ms per
division. The oscillator should run when the MCU PWR LED is on.
There should be approximately two divisions per cycle. This corre-
sponds to a 4.9152-MHz signal, the frequency required for a 9600-
baud communications rate. If the clock signal is not present, check
to see that a jumper is installed on W5. This selects the ICS08AB as
the source of the OSC1 signal.
M68ICS08ABUM/D
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