File: /~heha/hs/[Download]

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
Detected encoding: ASCII (7 bit)8