Lexicon RV-8 Service Manual page 61

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VFD Test
The VFD (vacuum fluorescent display) performs a busy test and a memory test. The busy test sends
information to the VFD and verifies that the VFD asserts then de-asserts its busy status. The VFD
memory test consists of writing 55h, AAh, a walking 1 and finally a 0 to the character generator memory
and display memory space of the VFD and reading them back. After the RV-8 has passed the VFD Test,
for the rest of the power on diagnostics, the VFD displays:
"DIAGNOSTIC TESTS
... ..."
The dots increment in number from both sides simultaneously, as the rest of the power-on diagnostic
tests are completed. This keeps you informed as to the functioning of the RV-8. If a failure occurs, the test
will attempt to enter a loop to exercise signal lines to aid in debugging.
Display for the Remaining Tests
If any of the following tests fail the VFD display and LED matrix will display the test and error fault, as
previously discussed. The VFD will display the test number and the error code. In the event that the VFD
is not operable, the same information will be written to the LED matrix. The test number will be read out
as in the top row. The error number can be read out in the second row (Most Significant Byte) and third
row (Least Significant Byte).
AVRX FPGA Test
The AVRX FPGA test verifies the ID register can be read from the XC2S200 on the main board. If a
failure occurs, the test will attempt to write the test number and the error number to the VFD.
CS49400 Test
This test verifies that the Crystal 49400 Decoder can communicate with the Host Hitachi processor
through the AVRX FPGA. If a failure occurs, the test will attempt to write the test number and the error
number to the VFD.
Power On Diagnostics Completed
After the power-on diagnostics are completed, the VFD will display the appropriate power up message:
"MANUFACTURER MODEL VX.XX
(c) 200X OPTIONS"
At this point the normal operating software takes over the functioning of the RV-8.
Debug Terminal Monitor Test (optional)
If the unit is not powering up correctly, monitor the boot sequence using a debug terminal monitor.
Test:
1. Power off the unit.
2. Connect a debug terminal monitor to the RV-8 RS232 serial port 2.
3. Power on the unit and monitor the boot sequence.
Note:
In order to see data on the debug port, use the following serial protocol:19200bps, 8, O, 1, (8 data bits,
Odd Parity, 1 Stop Bit).
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