Re: DDS Module is not functioning


William Kimber
 

Hi, If you are seeing traces blink I would slow the trace down so that it takes about 10 secs per sweep.  Just keep a careful eye on any blips.  Set the y  to about 5 volt for two divisions.

A counter in period mode might check how long it takes for the blink and also but separately how long the blips are.

cheers,
Will



On 17/08/15 16:09, Sead Kulenovic skulenov@... [PHSNA] wrote:
 



"'John King' jpking8@... [PHSNA]" je napisao:

 

Jim:
 
I did run some checks last night.  First, I established that there were good physical connections for the pins in question on both the DDS and Arduino.  No problem there.
 
I did check for activity as you suggest below.  After a software reset, I could not see actual pulses on any of the lines but I did see some repeatable phenomena.  For instance, after a software reset, the scope trace would momentarily blink and then after 5 seconds blink again.  This was true on all three lines you mentioned and on both modules and could be related to the five second wait after a software reset.  On a frequency range, there was an immediate trace blink after each change on all three lines.
 
I would feel more confident if I could see some actual pulses related to activity.  The problem may be scope settings (amplitude, sweep rate, trigger method, etc.).  Can you give me some idea of the pulse widths and pulse amplitudes I should be seeing?  Is there a reliable trigger I can use?  Please send along any ideas.
 
BTW, the equipment I am using is a Tektronix 7000 scope, probably from about the 1980's and government surplus.  It is a dual channel/trace 100 MHz scope with capabilities much like the 465.  Difference is that it uses plug in modules for vertical amplifiers and other vertical axis components like a spectrum analyzer.  My version has the same capabilities as a normal dual trace scope.
 
Thanks for the help.
 
John, W5IDA


From: PHSNA@... [mailto:PHSNA@...]
Sent: Thursday, August 13, 2015 4:31 PM
To: PHSNA@...
Subject: [PHSNA] Re: DDS Module is not functioning

 

You've established that the Arduino and the PC are communicating,
And that the clock oscillator is working.

Of course the DDS could be dead for some reason, but presuming the best case for now... ...

Lack of RF at both the output to the PHSNA and at J4 is often a symptom that the Arduino is not communicating with the DDS module, such that the DDS chip has not received a valid frequency and phase sequence after a reset.

Can you check with a scope for activity on the FQ-UP, WCLK, and D7 lines both after a software reset and whenever a frequency change command is issued. Check for the signals at the pins on the Arduino and also at the pins on the DDS module.

Jim, N5IB




---In PHSNA@..., wrote :

I can't seem to cause any output to come from the AD9851 synthes


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