KitsAndParts.Com Forum

wa2mze wrote:

Hi Diz,
Glad to see the new kit posted for release soon.
I have some questions on the schematic though...
Why not share the MOSI and SCL lines with the DDS and the program interface?  This works fine since they are inputs to the DDS and won't interfere with the SPI programmer, I've done this on my development board for the DDS-60 with an ATmega16.

Also you used a serial to parallel ('164) chip in the interface to the LCD, but there were more than enough io lines from the processor to not need this.  Even worse, you used the rxd and txd lines to do this, I would have left the uart available for firmware update via a bootstrap loader, or for computer control of the dds via a serial command set.  If I build this into a rig I'd like to be able to control it from my computer with a gui front panel.

I'm guessing you left all of port C unused for switching BP filters etc, but here you could have used a '595 as an io expander, and THAT could also have been driven by the SPI lines with just one more line to latch the output of the '595.  The spi can load both the DDS and the serial IO expander at the same time, only the chip that receives the FSYNC or LE will actually USE the new data. 

Finally why the trimmer on the cpu crystal?  I'm guessing you're thinking of a real time clock function and want to net the crystal to keep time.  Also the 20.24 crystal a bit more than 1% over the rated clock speed (probably not a problem), but a 20mhz crystal is a bit more common and with the neting cap you can still get a timer output of 1 sec right on the money.

73's
Ken, WA2MZE

Hi Ken,

There is no rhyme or reason for using one I/O pin vs another.  You have the option of changing pins and rewriting the sortware at will.
This kit is a "DEVELOPMENT KIT" which means you can do whatever you want, provided you have a $34.00 AVRISP programmer.
The CPU has a trimmer on the clock "IN CASE" you decide you need an accurate clock for the CPU. It only costs an extra 25 cents.
This part will work fine at 25 MHz, and 20.48 is not a stretch for the CPU. It produces a nice 1 millisecond timing period for delays, etc.
I also extend the DDS chip to 100 MHz, which is no problem, especially since I supply 3.3 volts vs 2.7 volts to the digital part of the DDS.
And why do I use the HC164 chip...simple...I want all the I/O pins available for "other" stuff, if you decide you need them.
Again, this is a development system, not a hard coded DDS VFO, where one size fits all.
Hope I make sense 

73, Diz, W8DIZ

W4GNS wrote:

Can I assume that folks will NOT have to spend $34.00 on a certain programmer ? Maybe a clone or something like this
http://www.e.kth.se/~joakimar/hardware.html    I don't see why not, unless I'm missing something, after rereading the homebrewed webpage, it does not appear to support the Mega88............

BTW, Diz, How did you manage to find my blog ? I don't have it linked to anything, I just noticed today I don't  even have a link on my useless webpage 

73 Gary W4GNS

Hi Gary,

The AVR DDS DEV Kit will include all software (firmware) to function as a semi-dual VFO used in a conversion type transceiver.
In transmit mode, the DDS will output the fundamental primary transmit frequency.
In receive mode, the DDS will output the MIXER frequencey, which is transmit frequency +/- the IF frequency.
You will have the option to custom program the ATmel AVR chip using a programmer.
The only programmer that "I" guarantee to work is the ATmel AVRISP-II (USB conection) but I'm sure other less expensive programmers will work fine.

As for your blog...not sure how I found it...think I was looking for your email address, or maybe I was searching porn sites

73, DIz

I think this will be a great addition....can't wait to get my hot hands on one...I am struggling with an ATMEL AVR ATmega USB programmer (China clone) and the darn thing will not play with my Vista 64 PC.  I tried to use AVR Studio but the USB driver will not install....I was really hoping to sink my teeth into the firmware of some of the AVR stuff....does this mean I need to buy another PC or OS?

Oh....also thanks Diz for getting the freq standard out to me so fast....it is really sweeeeet!!...now all my cheap counters will all be the same frequency.........

73, Bob W8UUU

I'm going to have to pick up a few atmega328's to play with when this board comes out.  I noticed that you didn't hard wire anything but the '164 pins to the micro so I can rewire it as I see fit.  I already see how I can wire up a keypad with some external glue.  Also will need to hook up a pair of '595's to control relays or diode switches for BPF's, BFO rocks, and such for multi band operation.  We will need a ptt input so the micro knows if it's in transmit or receive, and finally something weird, one IO line (interrupt) will be for an IR receiver (I intend to use a remote control with this!).

Maybe 'diz would allow me an option to leave out the rotary encoder and atmega88 parts and save a few cents.  I will supply my own (I've got some nice optical encoders with 32 detent positions and press switches in the junk box and the '88 isn't big enough for my ideas).

Yes I am logged on a an Admini$trator...come to find out that when you install AVR Studio from Atmel, it installs a "Jungo" driver...kinda like some "junko" driver for USB....it does not play well with Windoze Vista 64 or Win7 64bit OS....this stuff is getting too complicated for the developers when Atmel puts stuff like that in their packages...I am going to remove the Junko driver (if it will let me without changing the registry)  and start all over again...well off to find a fix...maybe "Linux"...then I am not too fond of the alternative software....I suppose that may be my only recourse...I may break out a copy of Minty...

Diz ....start packaging up the DDS vfo....I need one bad...lol...73, Bob, W8UUU

W4GNS wrote:

Are you working in Window$ as an Administrator ?  Have you checked the website and or ask for Vista drivers from the folks you bought it from ? It would not hurt to look and ask, Good Luck with the clone . I'm contemplating messing around with Atmel products again, and I'm thinking of buying the  AVRISP programmer Diz suggest, as he is smarter than I and gives the impression that the  AVRISP programmer the only way to fly, though normally I go the clone route to save a dollar or so. I did reinstall my C compiler today, I really really hate C, but guess I need to get to it and come proficient in C, as there are allot of reallly cool AVR projects on the web, with 99% in C

W8UUU wrote:

I think this will be a great addition....can't wait to get my hot hands on one...I am struggling with an ATMEL AVR ATmega USB programmer (China clone) and the darn thing will not play with my Vista 64 PC.  I tried to use AVR Studio but the USB driver will not install....I was really hoping to sink my teeth into the firmware of some of the AVR stuff....does this mean I need to buy another PC or OS?

Oh....also thanks Diz for getting the freq standard out to me so fast....it is really sweeeeet!!...now all my cheap counters will all be the same frequency.........

73, Bob W8UUU

I used to use dialup with Linux and it worked well.  There is a script that will run in the background to auto dial up when your browser (or any other program) tries to connect to a 'wan' address, but I just started it manually.  I also had the box set up to act as a router so once I dialed up all the computers on my 'lan' would also have access to the internet.  Then we finally got ISDL, then 'real' DSL.    The problem with Linux and dialup today is that so many computers come with these shitty 'windmodems' that do NOT have drivers for Linux.  You might have to find an old external modem and connect to if via a serial port (or usb to serial dongle).

W4GNS wrote:

I just looked over Diz's new DDS kit again, Am I understanding correctly that the software will either be open source, or will be available for those who purchase the kit ? I'm thinking it will be the latter, if either. Thats the only way I see it as an development kit.  If available will it be in C, or I dare mention assembler ?

It will be totally open source...then you can all see how bad my code is
The kit will come with the ATmel CPU, programmed.
And it WILL be ASSEMBLER, which to me is easier than "C". - Diz

I haven't tried programming AVR's in assembler, though I've sloshed through dis-assembler outputs to fix cases where the complier optimized away some important line of code!  At least the AVR assembler is easier to read and code than PIC's!
(GD bank switching!)

Hello Diz, Tom,

Long time no *see* Is this kit available yet? Perhaps more specs about output impedance/available power ?

Adrian, YO6SSW

That kit sounds really interesting... especially as the code will be open source.  I've had a neighbor offer to give us a radio he has- and if it's the one I think it is, this kit (and replacing the IF with my softrock) will turn that radio into something any ham would be proud of!

Then, too- I've also thought of converting a SSB CB (one of the things that survived the fire- I think) I have into 10 or 12 meters, and a DDS would be perfect for that!

Well, I guess I need to save my pennies!  (GRIN!)

What kit do you recommend for programming the ATmel?  A friend of mine and I have been thinking about them... we have some projects that we're planning on building (like a volts-to-rs232 adapter).  We'd be interested in suggestions.

Hi Adrian,
Good to hear from you again.
Tom, ak2b

W8DIZ wrote:

DDS DEV KIT output is about 5-10 mWatts at 50 ohms from 2 - 30 MHz
See the latest schematic at http://kitsandparts.com/DDS-Dev-Kit.php
Still waiting for some parts to arive, but the kits are mostly complete.
100 kits will be available.

That's great Diz. I was thinking of acquiring this kit and put it in a box along with antan's rf bridge. That would allow me to use it as a signal generator / antenna analyzer combo. I wanted to use the FCC-1/FCC-2 in this regard but the mechanical part proves to be a bit too hard for mechanical challenged people like myself.

W8DIZ wrote:

And lots of documentation needs to be written. Any volunteers? - Diz

If there's anything I can do to help please say so and I will gladly lend a hand ( even two )

ak2b wrote:

Hi Adrian,
Good to hear from you again.
Tom, ak2b

Tom, even though I have been busy with my final thesis in the last period, I have watched your progress both on Diz's forum and on EMRFD yahoo group and I would just like to point out how much I admire your dedication and the worthy results you get. A true ham spirit.

Also kudos to Diz for finding the time and will to design/test/provide all the useful kits.


Adrian, YO6SSW