Motorola M68LC302CAF20VCT User Manual page 60

Technical Reference and Troubleshooting
User's Manual
60
problems. If the MCU power LED is off, start the ICS08RKZ
simulator software as described in 2.4 Installing the Hardware
while watching the MCU power LED.
If the MCU power LED does not light at all, there may be a problem
with the host PC communicating with the board. Refer to step 5.
If the MCU power LED flickers a few times and then goes out, the
host PC is able to control the power to the RKICS board but
communications may still not be established with the MCU. As the
flickering of the MCU power LED indicates, the host PC is
applying and removing power to the RKICS board during this
period. Use an oscilloscope to view the voltages on TP1 and TP2 as
the software tries to establish communication with the MCU.
Restart or retry the ICS08RKZ software while looking at the
signals. Using the side pin on P1 (DC INPUT jack) as the ground
reference, check for a signal that varies between 0 and +3.3 Vdc at
TP2 (MCU V
DD
these voltages are present, the power is good, but communication
problems should be investigated as described in step 5.
If the MCU power LED comes on and stays on, communication
probably was established with the MCU. Check for the following
voltages, using the side pin on P1 (DC INPUT jack) as the ground
reference:
◊ Approximately +7.5 Vdc at TP1
◊ Approximately +3.3 Vdc at TP2
If these voltages are present, the power is good, and the
problem lies elsewhere.
5. Make sure that the host PC can communicate with the MCU:
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
communications. The target connector PTA0 pins (J3 pin 1,
J1 pin 2, and J2 pin 7) are never connected 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 RKICS
and to the correct serial port on the host computer.
Technical Reference and Troubleshooting
) and between 0 and +7.5 Vdc at TP1 (V
M68ICS08RK In-Circuit Simulator — Rev. 1
). If
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