This AD9834 DDS demo program expects two fixed wirings
for the control lines of the DDS chip.
│Parallel port assignment (same as for evaluation board, see datasheet)
└──────────────────────────────────────────────────────────────────────
SubD25♂ │Signal │Cen36 │AD9834 │Pin │Meaning
────────┼───────┼───────┼───────┼───────┼──────────────
2 │D0 │2 │SCLK │14 │Serial Clock
3 │D1 │3 │SDATA │13 │Serial Data
4 │D2 │4 │FSYNC │15 │Frame Sync, compatible to /SlaveSelect SPI signal
14 │/AF │14 │RESET │11 │High-active reset
18 etc. │GND │19 etc.│DGND │7 │Reference potential
Use an old-style IEEE1284 printer cable for connecting the evaluation board.
│Serial port assignment (merely to overcome missing parallel ports)
└──────────────────────────────────────────────────────────────────
SubD9♀ │Signal │Res. │Cen36 │AD9834 │Pin │Meaning
────────┼───────┼───────┼───────┼───────┼───────┼──────────────
4 │DTR │10 kΩ │2 │SCLK │14 │Serial Clock
7 │RTS │10 kΩ │3 │SDATA │13 │Serial Data
3 │/TxD │10 kΩ │4 │FSYNC │15 │Frame Sync
* │* │ │14—30 │RESET │11 │High-active reset (not used)
5 │GND │- │29 │DGND │7 │Reference potential
* On serial port, a fourth output is not available,
therefore, the RESET line is not used and tied to GND.
The necessary adapter fits into a 36-pin Centronics plug (see photo).
For new designs, I recommend this wiring.
│USB->Printer adapter wiring
└───────────────────────────
This configuration requires more changes to the evaluation board.
However, transfer speed is superious in comparison to previous wirings.
At first, replace the (socketed!) 74HC244 by a 74HC574 octal flip-flop.
Then wire resistors (ca. 1 kΩ) and bridges according to photo.
This wiring enables the backdoor to the previous wirings by
simply replacing the 74HC574 back to 74HC244.
This circuitry simulates a working printer to the USB->Printer adapter
that catches all the data.
At the output side of the 74HC574, there is now an (up to) 8-bit output port.
heha, 100815
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