Build a PIC controlled DDS VFO, 0 to 6 MHz using pic microcontroller
Files contained in MINIDDS.ZIP:
readme.txt Read this first! compplac.pdf Component placement in PDF format schema.pdf Schematic diagram in PDF format top.ps PCB top copper layer in Postscript format bottom.ps PCB bottom copper layer in Postscript format ad9832_4.asm PIC assembly source code p16f84.inc Needed for assembly of ad9832_4.asm (for 'F84) p16c84.inc As above but for 'C84 vfo5x7f.hex PIC16F84 program for LCD with 5x7 font vfo5x10f.hex PIC16F84 program for LCD with 5x10 font vfo5x7c.hex PIC16C84 program for LCD with 5x7 font vfo5x10c.hex PIC16C84 program for LCD with 5x10 font filtresp.pcx Computed frequency response of lowpass filter
Download MINIDDS.ZIP (186K)
Download MINIDDS.PDF (209K)
If you prefer to control the DDS module from a PC (instead of using a PIC), try this:
Download PCVFO.ZIP (18K)
The zip archive contains a single file, VFO.EXE. It is a DOS program but it runs fine in a Windows 95/98 “DOS bubble” as well (see screenshots above).
Are you looking for a DDS based 136 kHz longwave transmitter exciter?
Have a look at G0MRF’s page
- Start-up frequency: 137.00000 kHz
- Tuning range: 135.70000 to 137.80000 kHz in 0.25 Hz steps
- DFCW offset: 0 to 50 Hz adjustable in 0.25 Hz steps
- The dial can be locked to prevent inadvertent QSY
- Calibration: +/- 200 ppm, stored in EEPROM.
- Actual DDS output frequency is 4 * dial frequency
Schematic and source code for the PIC controller is available here:
Download the PIC program lwex.zip
The encoder inputs also have internal pull-ups in the PIC.
The switches “LOCK”, “DFCW” and “CAL” are momentary pushbuttons.
For more detail: Build a PIC controlled DDS VFO, 0 to 6 MHz
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