Also, data lookup tables are implemented in a wasteful fashion. There's no proper indexing. Control registers and memory are paged, so this can make things annoyingly complicated when you start to fill up memory with variables.Originally Posted by KC2UGV
What are you using for a PIC programmer - both the editor/assembler and the hardware itself?
I've been playing around with a DDS VFO unit which uses an AD 9851 and a BASIC Stamp but I'm starting to run into space constraints. A PIC may be better for what I'm looking to do.
"Everyone wants to be an AM Gangsta until it's time to start doing AM Gangsta shit."
Its a Velleman k8048. Just using a text editor, assembler and the hardware.
Not familiar with the BASIC stamp - but whatever you use control the DDS in interrupts triggered from the tuning control and the display in the main loop and it'll be nice and smooth :)
If controlling the DDS is particularly CPU intensive, then display update will take a back seat in a nice way without making the tuning sound weird when quickly tuning past a carrier. It will also be self limiting, so if you tune really quickly, it will max out the CPU at the maximum tuning rate, while ocassionally updating the screen.
You can notice exactly these effects on the big commercial rigs.
Last edited by mw0uzo; 12-17-2010 at 06:00 AM.
Got the QRSS textprint mode working. Had to write routines to mirror and flip the character data so it displays properly in QRSS grabbers. Really not as easy as it sounds, as it totally contradicted the way the textprint routine worked.
Can I Haz High Rezolution Font Plz?
- No.
Last edited by mw0uzo; 12-17-2010 at 09:28 PM.
There is no way to increase the dot count per character a little even? 1 more pixel wide, and one more tall would make legibility much easier, or even using something like what Feld Hell does. (1 full line, 1/2 line on top and bottom).Got the QRSS textprint mode working. Had to write routines to mirror and flip the character data so it displays properly in QRSS grabbers. Really not as easy as it sounds, as it totally contradicted the way the textprint routine worked.
Can I Haz High Rezolution Font Plz?
- No.
Yeah one more pixel vertically and horizontally is possible without gobbling more ROM. That's it though, I only have 2kB of space for data and program and each byte is precious! Especially since i have not much left and another menu item and a few short routines to add.
Also not sure why the legibility is so bad on that FFT. My receiver seems to be adding some distortion and the FFT resolution isn't that great either.
Last edited by mw0uzo; 12-17-2010 at 09:55 PM.
Hello.
A question.
Why a crystal oscillator with a heater and not a TCXO?
Pure sinewave TCXO reference sources are cheap.
Good question. A TCXO would have been excellent inside that little heated box. Not sure what scope there is for adding varicap tuning, but it would have been much less temperature sensitive than the discrete oscillator is. Just because really - i wanted to see how stable it was with bog standard components. It turns out not that stable. But stable enough for a simple beacon that will end up in a shed, exposed to wide ranges of temperature. Without the heater, it would have been all over the place. Its temperature sensitivity is about 1Hz per degree!
I've increased the text size vertically by one pixel. Still having trouble getting good print in the QRSS grabber. Played around with FFT and sample rate settings with a small amount of success but no joy.
Not sure what it is - maybe the line scanning is blurring out the pixels?
Also can't remember what settings I used to get the picture posted above!
Last edited by mw0uzo; 12-18-2010 at 02:29 PM.
Taller font in standard mode
Taller font in QRSS mode
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