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 filterDownload 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).
Almost any 2x16 character LCD module with Hitachi HD44780 controller chip will work. The LCD pin numbers on the schematic are not valid for all LCD modules. Please check the actual signal names on your particular LCD module.
The selected DFCW frequency offset will be added to the output frequency when the DFCW input is grounded. This input has a weak pull-up in the PIC.
The encoder inputs also have internal pull-ups in the PIC.
The switches "LOCK", "DFCW" and "CAL" are momentary pushbuttons.
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