Technical Reference and Troubleshooting
Troubleshooting the Startup
M68ICS08JLJK In-Circuit Simulator — Rev. 0 User’s Manual
MOTOROLA Technical Reference and Troubleshooting 61
inserted correctly. Connect the serial cable between the host PC and
the JLJKICS. Apply power to the JLJKICS. Start the ICS08JLZ
simulator software as described in 2.4 Connecting the Hardware.
Probe the PTB0 pin (U13 and U16 pin 21 or U14 and U17 pin 15)
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 PTB0 pin is affected also.
5. Make sure that the MCU has a good clock source. Use an oscilloscope to
check the OSC1 pin at the MCU (U13 and U16 pin 4 and U14 and U17
pin 3). Set the oscilloscope to 0.1 µs per division. The oscillator should
run when the MCU power LED is on. Approximately one division per
cycle should be observed for a 9.8304-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 JP4. This selects the
JLJKICS as the source of the OSC1 signal.
6. Make sure that the MCU can enter and remain in monitor mode. For this
to happen, the following conditions must occur:
a. At the rising edge of RST, IRQ must be at VMON (+7.5 Vdc). Using
a dual-trace oscilloscope, trigger channel 1 on the rising edge of
RST (U13/U16 pin 28, U14/U17 pin 20) and read the IRQ pin
(U13/U14/U16/U17 pin 1) with channel 2. Start the ICS08JLZ
software as described in 2.4 Connecting the Hardware and verify
that the IRQ signal is approximately +7.5 Vdc when RST rises. If
IRQ is not at +7.5 Vdc, there may be a problem with the JLJKICS
board’s IRQ circuit. The timing of the reset pulse and the monitor
mode control signals on port B is controlled by the 74HC123-based
circuit on sheet 3 of the schematics.
b. At the rising edge of RST, PTB1, PTB2, and PTB3 must be held at
logic values 1, 0, and 1, respectively. Using a dual-trace
oscilloscope, trigger channel 1 on the rising edge of RST and read
the corresponding MCU pin with channel 2. PTB0 is the serial data
pin to and from the host PC and should be around +3.3 Vdc at the
rising edge of RST. Analog switch U4 is used to put the default
monitor mode configuration onto PTB1, PTB2, and PTB3 at the
end of reset. These pins are available for processor I/O at other
times. The MCU’s PTB0 pin is never connected to the target pins,
as it is used for host communication.
Freescale Semiconductor, I
Freescale Semiconductor, Inc.
For More Information On This Product,
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