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APPENDIX A – TECHNICAL REFERENCE & TROUBLESHOOTING
5. Make sure that the host PC can communicate with the MCU:
A-6
(VTST_RST). If these voltages are present, the power is good, but
communication problems should be investigated as described in
step 5.
If the MCU PWR LED comes on and stays on, communication was
probably established with the MCU. Check for the following volt-
ages, using the side pin on P1 (DC INPUT jack) as the ground ref-
erence:
Approximately 9.0 Vdc at TP1 and TP2
Approximately 5.0 Vdc at TP3
If these voltages are present, the power is good, and the problem
lies elsewhere.
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 target connector PTA0 pin (J1 pin 30) is never con-
nected to the MCU's PTA0 pin. They are wired only for probing
purposes.
b. Make sure that the serial cable is correctly attached to the ICS08AB
and to the correct serial port on the host computer.
c. Make sure that the cable is a straight-through cable supporting all
nine pins of the serial port connection.
d. Make sure that no hardware security key or other devices are
attached to the serial port or cable.
e. Make sure that the host PC supports the minimum speed require-
ments of the ICS08ABZ software.
f. 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.
g. Check for data at the ICS08AB end of the serial cable. Pin 3 of this
connector carries RS-232 data into the ICS08AB; pin 2 carries RS-
232 data out of the ICS08AB. Pin 4 controls the MCU PWR. Pin 5
is ground. While the ICS08ABZ software is trying to establish
communications, pins 3 and 4 should both toggle between +10 Vdc
and –10 Vdc (or +12 Vdc and –12 Vdc). If you do not see these sig-
nals at the cable end, the problem is on the PC and cable side of the
system. When connected to the ICS08AB, a +10 Vdc signal on pin
4 should activate the ICS08AB and the MCU PWR LED.
M68ICS08ABUM/D
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