News, Updates and Other Minutiae
August 2019
Website outage - I made some hosting changes and there was a minor hiccup. Hopefully everything is now back to normal but please let me know if anything is missing.
The start of a new project added in the Homebrew category. Specifically, a Frequency Dependant Switch. Measures the incoming frequency and switches 1 of 8 outputs on. Software for this project uploaded.
June 2019
Added another project for the AD9850 DDS modules. A Simple DDS sweeper in the Homebrew section. This is an absolutely basic, no frills project using a 12F1840 to sweep a DDS module between a range of frequencies. Plenty of scope for you to improve on the software and add extra features.
Privacy Policy uploaded. It may be viewed at the Privacy Policy link in the footer.
Custom code/webhost costs
I have, for quite a while, provided modified versions of the code for my projects free of charge. However, the cost of webhosting for this site has tripled in the last few of years and shows no signs of getting any cheaper.
As of October 2017, I will be asking for a donation in exchange for providing custom modified code for my projects to help keep this site available.
GPDR and all that stuff
In accordance with various bits of legislation around the world, either currently in force, about to come into force or proposed, you will now find that annoying "We use cookies" notice at the top of this website. Please note that the ONLY cookies currently used on this site are for that pop-up (see https://cookieconsent.insites.com/) and Google Analytics. The full Privacy Policy is available at the Privacy Policy link in the footer at the bottom of the page. (If you don't know what GPDR is, Google it. Real scary shit for ANYBODY with a web presence.)
This project can be built using the Simple DDS VFO pcb. Use the contact page to get in touch with me to order. November 2019 - pcb's still available.
Simple Sweeper
A Simple DDS based sweeper using an 8-pin PIC.
This is a very basic, no frills and simple sweep unit using an AD9850 (or AD9851) module and a 8 pin PIC. It came about from a request by a user of my Simple DDS VFO. There are no bells and whistles, user controls (other than an on/off switch) or trigger output and the sweep frequency (beginning and end) needs hard programming in. The step frequency is hard coded at 5kHz in the demo software below (which sweeps 50kHz to 30MHz), but could be reduced to a smaller value if the beginning and end frequency are reduced to a smaller range. It takes approximately 1 second to sweep the range from 50kHz to 30MHz at 5kHz steps. This will increase to about 3 seconds if the step size is reduced to 1kHz. To get this rate of sweep, a much faster PIC than the 12F629 is required, so a 12F1840 running at 32MHz has been used. There are 3 pins unused currently, two of which can be either input or output and one that is an input only. With appropriate programming, extra features could be added using these pins. No option to calibrate the DDS frequency is available in the software, although it could be added if deemd necessary or, by trial and error, the Ref_osc values can be manually adjusted. Go at it, experiment with the software and see how much more you can get out of such a simple project, there is a LOT of code space remaining. If you do add significant features or improve on the software, please let me know so it can be added to this page.
Software
The demo software provided below is very basic and no attempt to optimise it (except where necessary) to use the expanded range of commands available in the enhanced range of PIC's has been made (including the use of LATA instead of PORTA for writes to the port). You will need to input the values of and recompile the software for your required start, stop and step size frequencies: Limit - The upper limit frequency you want the Simple Sweeper to reach. Starts at line 90. Limit_Low - The lower limit frequency you want the Simple Sweeper to start at. Starts at line 98. Step size - The size of the frequency steps. You will find this at line 278 in the asm file.
Downloads
These files are provided free for personal use ONLY. I retain copyright on all works published on this website (unless otherwise specified). These files, or any derivative of them, may NOT be used in any commercial or profit making enterprise of any kind. I no longer make pcb files available because of copyright infringement.
(Right click and 'Save as..' or what ever is required by your browser) simple_sweep.asm The ASM file for the Sweeper. It is set to AD9850 by default. Instructions in the file to change it to AD9851. Default range 50kHz - 30MHz, 5kHz steps. simple_sweep.hex AD9850 hex file.
