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  Topic: ATmega168 for DDS
davidapex

Replies: 10
Views: 1419

PostForum: BASCOM-AVR Archive   Posted: Fri Aug 18, 2006 11:31 am   Subject: ATmega168 for DDS
Hello Luciano,
Sorry for the confusion - I was hinting that the AD9833 would replace the entire DDS software, ATmega 168 and DAC. The attraction is the hardware based DDS allowing higher speed and y ...
  Topic: ATmega168 for DDS
davidapex

Replies: 10
Views: 1419

PostForum: BASCOM-AVR Archive   Posted: Thu Aug 17, 2006 10:41 am   Subject: ATmega168 port/pin problems
Hello Luciano,
Apologies for the delay in responding to your idea. This looks like the best way to go but I think I still have a problem. The DAC is actually a SIP R-2R ladder network from Dale and ...
  Topic: Mega168 reset pin.
davidapex

Replies: 5
Views: 465

PostForum: BASCOM-AVR Archive   Posted: Mon Aug 14, 2006 11:52 am   Subject: Mega168 reset pin.
Hi Luciano,
I don't know why I couldn't see your post earlier.
Many thanks for the detailed explanation which now sounds very similar to Pics which todate I have only used on high voltage programmin ...
  Topic: Mega168 reset pin.
davidapex

Replies: 5
Views: 465

PostForum: BASCOM-AVR Archive   Posted: Mon Aug 14, 2006 10:29 am   Subject: Mega168 reset pin.
Hello Ian,
Many thanks for the quick feedback.
I can't believe this - I do it routinely with Pics, hence the screw-up on my part.
....I'll give it high voltage alright! Come to think of it, the P ...
  Topic: Mega168 reset pin.
davidapex

Replies: 5
Views: 465

PostForum: BASCOM-AVR Archive   Posted: Mon Aug 14, 2006 9:50 am   Subject: Mega168 reset pin.
Hi,
I just discovered how to configure the reset pin on a mega168 as an I/O but I now wish I hadn't.
I don't seem to be able to indentify/programme the chip any more and thinking about it that would ...
  Topic: ATmega168 for DDS
davidapex

Replies: 10
Views: 1419

PostForum: BASCOM-AVR Archive   Posted: Sat Aug 12, 2006 9:06 am   Subject: ATmega168 for DDS
Hi Ian,
I think you are right and I should bite the bullet and have a go myself.

I still can't believe the dumb way the chip has been arranged. If you were wanting a xtal timed UART you lose both ...
  Topic: ATmega168 for DDS
davidapex

Replies: 10
Views: 1419

PostForum: BASCOM-AVR Archive   Posted: Sat Aug 12, 2006 6:47 am   Subject: ATmega168 for DDS
Hi All,
A while back I got involved with the DDS code posted by Luciano and had this running nicely (with internal oscillator) on an ATmega 168.
Then by chance I obtained a crystal oscillator with t ...
  Topic: Direct Digital Synthesis. (DDS)
davidapex

Replies: 81
Views: 19853

PostForum: BASCOM-AVR Archive   Posted: Sat May 20, 2006 1:39 am   Subject: Direct Digital Synthesis. (DDS)
Hi All,
Just confirming the fix that Luciano posted - everything is now perfect.
I can now enter 100, 1000, 10,000, 100,000, 1,000,000 and the decimal point on the frequency counter just shifts alon ...
  Topic: Direct Digital Synthesis. (DDS)
davidapex

Replies: 81
Views: 19853

PostForum: BASCOM-AVR Archive   Posted: Sat May 20, 2006 1:18 am   Subject: Direct Digital Synthesis. (DDS)
Hello Luciano,
Thanks for confirming that I'm not getting too old for this activity.
I would like to nod my head in agreement with your finding but to be honest I can't see why the delay is value de ...
  Topic: Direct Digital Synthesis. (DDS)
davidapex

Replies: 81
Views: 19853

PostForum: BASCOM-AVR Archive   Posted: Fri May 19, 2006 1:43 pm   Subject: Direct Digital Synthesis. (DDS)
Hello Luciano,
I did just format a reply to your post but the button I hit sent it off to data heaven. Here we go again.

The table I have shown is r24/r25/r26 value againt frequency output

Fis ...
  Topic: Direct Digital Synthesis. (DDS)
davidapex

Replies: 81
Views: 19853

PostForum: BASCOM-AVR Archive   Posted: Thu May 18, 2006 11:29 am   Subject: DDS
Hi All,
As a final footnote to this interesting thread I have observed a curious trend in the input number vs output frequency of this DDS.

With the 8MHz oscillator the 24 bit phase accumulator re ...
  Topic: Direct Digital Synthesis. (DDS)
davidapex

Replies: 81
Views: 19853

PostForum: BASCOM-AVR Archive   Posted: Wed May 17, 2006 9:19 am   Subject: DDS
Hello Luciano,
That's fantastic! Worked like a treat. E-beers all round.

I very much appreciate the time you have taken to develop the code and although I now have a great solution I still need ...
  Topic: Direct Digital Synthesis. (DDS)
davidapex

Replies: 81
Views: 19853

PostForum: BASCOM-AVR Archive   Posted: Tue May 16, 2006 3:03 am   Subject: Direct Digital Synthesis. (DDS)
New theory - I think the RETI instruction is being ignored and the code simply runs in to the Goto Keypad instruction a couple of lines further on. I don't think it is going to the assembler routine ...
  Topic: Direct Digital Synthesis. (DDS)
davidapex

Replies: 81
Views: 19853

PostForum: BASCOM-AVR Archive   Posted: Tue May 16, 2006 1:32 am   Subject: Direct Digital Synthesis. (DDS)
Hello Luciano,
It may be time to give up on your worst student.

A quick change of code gives the following results:

An active low on the PCInt0 pin (portb.7) puts it in to keypad entry mode.
U ...
  Topic: Direct Digital Synthesis. (DDS)
davidapex

Replies: 81
Views: 19853

PostForum: BASCOM-AVR Archive   Posted: Mon May 15, 2006 9:39 pm   Subject: Direct Digital Synthesis. (DDS)
Hi All,
Attached is my last attempt to ***** this before trying something a little easier such as blinking LEDs.

The code starts up outputing a garbage waveform as I have removed the starting valu ...
 
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