Topics

DDS Module is not functioning

John King
 

I can't seem to cause any output to come from the AD9851 synthesizer I have on my Type I PHSNA main board.  The synthesizer was working normally until I removed the module in order to remove components of the onboard lowpass filter and replaced L1, L2 and L3 with 0.0 Ohm SMT resistors.  Only the lowpass filter elements were modified from the original circuit.  When I finished the replacement, I put the DDS back in place and observed that it no longer had output.


Thinking that I had made some mistake with the modification, I made a few checks.  First, I reset the Seeduino and observed that the information window on Nick's Windows control program did report that the Seeduino was using version 1.6.  This indicated the Arduino and Windows program recognized each other.  I then checked the DDS clock and found that it was putting out a signal.  I also checked for 5 VDC on the DDS module.  My multimeter showed 4.95 VDC.  Then, I pulled the DDS module and made some resistance measurements.  The meter reads 200 Ohms from the top of the pad that used to contain R9 to ground.  The meter also reads 0.0 Ohms from the top of R7 to the top of the R9 pad.  This indicates to me that the modification was acting as it should.


Replacing the module, I found that the reading between the R9 pad and ground was now 0.0 Ohms.  This was most likely because the module output was now connected to the off-module transformer on the main board, as it should be.  I also checked for RF on J4 of the DDS module to see if  the main output might be shorted.  There was no output on J4.


These symptoms occurred once before a couple of months ago, before I had made the low pass filter modification.  At that time, there was no output from the DDS as well.  Jim, N5IB suggested that I make the tests described above.  He then sent me a parameters file which contained the usual data (calibration points, COM port, etc.).  I installed the file and my problems seemed to go away.  The DDS produced output and its frequency could be changed as needed.


I am now wondering if the parameters file was really the problem, or if the module was intermittent and simply began working at that time.  At any rate, I am confused as to what to try next and would like suggestions from the PHSNA gurus among you, to include Jim and Nick.


Thanks in advance,

John, W5IDA

N5IB
 

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@..., <jpking8@...> wrote :

I can't seem to cause any output to come from the AD9851 synthesizer I have on my Type I PHSNA main board.  The synthesizer was working normally until I removed the module in order to remove components of the onboard lowpass filter and replaced L1, L2 and L3 with 0.0 Ohm SMT resistors.  Only the lowpass filter elements were modified from the original circuit.  When I finished the replacement, I put the DDS back in place and observed that it no longer had output.


Nick Kennedy
 

That's a tough one.  I did modify one of the eBay DDS units initially, but later changed to the DDS-60. Modifying that tiny SMT board was tricky.  I don't have much specific to offer, but in my case, I make good use of a 10x jeweler's loupe when doing that kind of work.

Checking for continuity (whether required or unintentional) can be difficult when starting from those TSSOP pins.  I'll clip a straight pin from my wife's sewing box to my DMM leads and then use my jeweler's loupe to help me hit the pin correctly.

Otherwise ... looking at the schematic I recall that the DDS chip's RESET pin *is* used on the Chinese boards and our Arduino hardware and software does hit that pin.  So it might be good to make sure the reset is getting there.

Have you hit the reset button on the Arduino after powering up? Might be worth a try, although since your PC is communicating with the Arduino, it appears to be running.  Still, I've had this work for me.  Maybe the extra reset of the DDS chip when restarting the Arduino is what does the trick.

Good luck with it.

73-

Nick, WA5BDU

On Thu, Aug 13, 2015 at 1:02 PM, jpking8@... [PHSNA] <PHSNA@...> wrote:
 

I can't seem to cause any output to come from the AD9851 synthesizer I have on my Type I PHSNA main board.  The synthesizer was working normally until I removed the module in order to remove components of the onboard lowpass filter and replaced L1, L2 and L3 with 0.0 Ohm SMT resistors.  Only the lowpass filter elements were modified from the original circuit.  When I finished the replacement, I put the DDS back in place and observed that it no longer had output.


Thinking that I had made some mistake with the modification, I made a few checks.  First, I reset the Seeduino and observed that the information window on Nick's Windows control program did report that the Seeduino was using version 1.6.  This indicated the Arduino and Windows program recognized each other.  I then checked the DDS clock and found that it was putting out a signal.  I also checked for 5 VDC on the DDS module.  My multimeter showed 4.95 VDC.  Then, I pulled the DDS module and made some resistance measurements.  The meter reads 200 Ohms from the top of the pad that used to contain R9 to ground.  The meter also reads 0.0 Ohms from the top of R7 to the top of the R9 pad.  This indicates to me that the modification was acting as it should.


Replacing the module, I found that the reading between the R9 pad and ground was now 0.0 Ohms.  This was most likely because the module output was now connected to the off-module transformer on the main board, as it should be.  I also checked for RF on J4 of the DDS module to see if  the main output might be shorted.  There was no output on J4.


These symptoms occurred once before a couple of months ago, before I had made the low pass filter modification.  At that time, there was no output from the DDS as well.  Jim, N5IB suggested that I make the tests described above.  He then sent me a parameters file which contained the usual data (calibration points, COM port, etc.).  I installed the file and my problems seemed to go away.  The DDS produced output and its frequency could be changed as needed.


I am now wondering if the parameters file was really the problem, or if the module was intermittent and simply began working at that time.  At any rate, I am confused as to what to try next and would like suggestions from the PHSNA gurus among you, to include Jim and Nick.


Thanks in advance,

John, W5IDA


Gary Winblad
 

I was reading old posts..
There was some problem with the "reset" pin on some of the DDS
modules.  Connecting it to the Arduino (IIRC) fixed someone's problem.
I run a DDS-60 board that has 9851 reset connected directly to ground
so I don't seem to have a problem...
HTH,
73,
Gary
WB6OGD

John King
 


Hi, Nick.
 
I have some SMD experience, especially with 1208 and 0805 parts.  Generally, I use a lighted magnifier ring lamp for soldering and a 10X loupe for final inspection.  I generally start any PHSNA session by doing a hardware reset on the main board and a software reset on the Windows program screen.  I will have to look for the DDS reset and see what that does.
 
Thanks for the tips.
 
John



From: PHSNA@... [mailto:PHSNA@...]
Sent: Friday, August 14, 2015 10:44 AM
To: PHSNA@...
Subject: Re: [PHSNA] DDS Module is not functioning

 

That's a tough one.�� I did modify one of the eBay DDS units initially, but later changed to the DDS-60. Modifying that tiny SMT board was tricky.�� I don't have much specific to offer, but in my case, I make good use of a 10x jeweler's loupe when doing that kind of work.

Checking for continuity (whether required or unintentional) can be difficult when starting from those TSSOP pins.�� I'll clip a straight pin from my wife's sewing box to my DMM leads and then use my jeweler's loupe to help me hit the pin correctly.

Otherwise ... looking at the schematic I recall that the DDS chip's RESET pin *is* used on the Chinese boards and our Arduino hardware and software does hit that pin.�� So it might be good to make sure the reset is getting there.

Have you hit the reset button on the Arduino after powering up? Might be worth a try, although since your PC is communicating with the Arduino, it appears to be running.�� Still, I've had this work for me.�� Maybe the extra reset of the DDS chip when restarting the Arduino is what does the trick.

Good luck with it.

73-

Nick, WA5BDU

On Thu, Aug 13, 2015 at 1:02 PM, jpking8@... [PHSNA] <PHSNA@...> wrote:
��

I can't seem to cause any output to come from the AD9851 synthesizer I have on my Type I PHSNA main board.�� The synthesizer was working normally until I removed the module in order to remove components of the onboard lowpass filter and replaced L1, L2 and L3 with 0.0 Ohm SMT resistors.�� Only the lowpass filter elements were modified from the original circuit.�� When I finished the replacement, I put the DDS back in place and observed that it no longer had output.


Thinking that I had made some mistake with the modification, I made a few checks.�� First, I reset the Seeduino and observed that the information window on Nick's Windows control program did report that the Seeduino was using version 1.6.�� This indicated the Arduino and Windows program recognized each other.�� I then checked the DDS clock and found that it was putting out a signal.�� I also checked for 5 VDC on the DDS module.�� My multimeter showed 4.95 VDC.�� Then, I pulled the DDS module and made some resistance measurements.�� The meter reads 200 Ohms from the top of the pad that used to contain R9 to ground.�� The meter also reads 0.0 Ohms from the top of R7 to the top of the R9 pad.�� This indicates to me that the modification was acting as it should.


Replacing the module, I found that the reading between the R9 pad and ground was now 0.0 Ohms.�� This was most likely because the module output was now connected to the off-module transformer on the main board, as it should be.�� I also checked for RF on J4 of the DDS module to see if�� the main output might be shorted.�� There was no output on J4.


These symptoms occurred once before a couple of months ago, before I had made the low pass filter modification.�� At that time, there was no output from the DDS as well.�� Jim, N5IB suggested that I make the tests described above.�� He then sent me a parameters file which contained the usual data (calibration points, COM port, etc.).�� I installed the file and my problems seemed to go away.�� The DDS produced output and its frequency could be changed as needed.


I am now wondering if the parameters file was really the problem, or if the module was intermittent and simply began working at that time.�� At any rate, I am confused as to what to try next and would like suggestions from the PHSNA gurus among you, to include Jim and Nick.


Thanks in advance,

John, W5IDA


Pravin
 

Hi Gary,
If it is not inconvenient will you please let me know the modifications (hardware as well as software) you have made to PHSNA to turn it into a real time filter tester as discussed a couple of days ago. You may kindly send the same on my email id:- nivar_p @yahoo.co.in . Thanks for your time

73
DE AB9XC
(Pravin)

--------------------------------------------

On Fri, 8/14/15, wb6ogd@... [PHSNA] <PHSNA@...> wrote:

Subject: [PHSNA] Re: DDS Module is not functioning
To: PHSNA@...
Date: Friday, August 14, 2015, 9:51 AM


 









I was reading old posts..
There was
some problem with the "reset" pin on some of the
DDS
modules.  Connecting it to the Arduino
(IIRC) fixed someone's problem.
I run a
DDS-60 board that has 9851 reset connected directly to
ground
so I don't seem to have a
problem...
HTH,
73,
Gary
WB6OGD









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Gary Winblad
 

Nick,
What I did was modify your Arduino code (version where Windows does all
the work) with my additions (and some code from your Terminal control
version).
Would it be OK for me to post it to the Files folder for Pravin and others??
Or email it to him...?
Don't want to step on your hard and excellent work any more than I have
already.

73,
Gary
WB6OGD

Nick Kennedy
 

Gary,

Definitely go ahead and post your changes.  As long as you create your own folder and add a bit of text on what your variations do, I can't see any issues.  I think we've already had a number of hardware and software variations, which is all in the spirit of the project.

73-

Nick, WA5BDU


On Sat, Aug 15, 2015 at 9:52 AM, wb6ogd@... [PHSNA] <PHSNA@...> wrote:
 

Nick,
What I did was modify your Arduino code (version where Windows does all
the work) with my additions (and some code from your Terminal control
version).
Would it be OK for me to post it to the Files folder for Pravin and others??
Or email it to him...?
Don't want to step on your hard and excellent work any more than I have
already.

73,
Gary
WB6OGD


John King
 

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 synthesizer I have on my Type I PHSNA main board.  The synthesizer was working normally until I removed the module in order to remove components of the onboard lowpass filter and replaced L1, L2 and L3 with 0.0 Ohm SMT resistors.  Only the lowpass filter elements were modified from the original circuit.  When I finished the replacement, I put the DDS back in place and observed that it no longer had output.


N5IB
 

Hi John,

I grabbed a few scope snapshots for you.

I posted them in a new "Scope Traces" Album in the Photos area, since other folks may find them to be a useful troubleshooting reference.

These are taken from a Type II PHSNA running with standalone power. The reset was a hardware reset, done with the pushbutton connected to the reset line on the PHSNA. This unit is Bluetooth connected to the PC, so the reset within the Windows app doesn't function.

Jim, N5IB



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


John King
 

Jim:
 
Using your guidelines on setting up my scope, I did the tests you suggested.  I found the same behavior on all the pins you suggested (D7, FQ-UP and WCLK) on both the Arduino and the DDS.  In all cases, changing frequency resulted in only a single pulse at the time a button was pushed.  The pulse was about 0.5 V high and around 1 msec. wide.  None of the actions produced a pulse train as you showed on your scope photos, either on the DDS or the Arduino.  In no case, was there a signal from the DDS output.
 
Suggestions?
 
John, W5IDA



From: PHSNA@... [mailto:PHSNA@...]
Sent: Saturday, August 15, 2015 5:00 PM
To: PHSNA@...
Subject: RE: [PHSNA] Re: DDS Module is not functioning

 

Hi John,

I grabbed a few scope snapshots for you.

I posted them in a new "Scope Traces" Album in the Photos area, since other folks may find them to be a useful troubleshooting reference.

These are taken from a Type II PHSNA running with standalone power. The reset was a hardware reset, done with the pushbutton connected to the reset line on the PHSNA. This unit is Bluetooth connected to the PC, so the reset within the Windows app doesn't function.

Jim, N5IB



N5IB
 

Since the signals we're looking for are all produced by the Arduino, either

a) they are not being produced, or
b) something about the DDS board is dragging them down.

Try unplugging the DDS from the PHSNA.
Monitor those lines with your scope and do a hardware reset with the pushbutton.
See if there is any activity now.

Also, do you have any other Type I DDS you could swap out for, even if its a 9850 board?

Jim, N5IB






---In PHSNA@..., <jpking8@...> wrote :

Jim:
 
Using your guidelines on setting up my scope, I did the tests you suggested.  I found the same behavior on all the pins you suggested (D7, FQ-UP and WCLK) on both the Arduino and the DDS.  In all cases, changing frequency resulted in only a single pulse at the time a button was pushed.  The pulse was about 0.5 V high and around 1 msec. wide.  None of the actions produced a pulse train as you showed on your scope photos, either on the DDS or the Arduino.  In no case, was there a signal from the DDS output.

John King
 

Jim:

Tried your suggestion concerning the removal of the AD9851 and looking at the pins that way.  After several resets, hardware and software, I began to see multiple pulses when the frequency was changed up or down on the windows PHSNA software.  These multiple pulses  were about 5 Vdc and perhaps a major fraction of a millisec wide. (Not too sure on the pulse width as they were a bit hard to capture on a non-storage scope.  The pulses occurred on D7 and WCLK.  On FQ-UP, I saw a single pulse with a frequency change.


Since this activity is not entirely consistent from one time to the next, I think my next attempt will be to change the Arduino and program it with  the PHSNA software.  Then I will try the same experiment again, with and without the AD9851 in place.   My thinking is that we might have faults in both the Arduino and the AD9851,  In the meantime, I will order another AD9851 and see if that is the problem.  The second DDS might be good for a future project of some kind, even if I don't need it on the PHSNA..


BTW, the microprocessor I have been using is a Seeduino.  The new one will be a true Arduino Uno R3.


I will let you know what happens.  May take a while for the AD9851 to get here.


John, W5IDA

Tim
 

John
This is a long shot, are you programming Seeduino as Nano or Uno?
Mine is Nano and I selected Uno and it caused me a day of grief because the Seeduino board looks like a Uno.
Tim W4YN

John King
 

Thanks for the idea, Tim!
 
I programmed the Seeduino as a Uno R3, because that is exactly what it looked like.  I will research the documentation a bit and see if you have hit upon the solution.
 
John, W5IDA



From: PHSNA@... [mailto:PHSNA@...]
Sent: Thursday, August 20, 2015 7:38 AM
To: PHSNA@...
Subject: RE: [PHSNA] Re: DDS Module is not functioning

 

John

This is a long shot, are you programming Seeduino as Nano or Uno?
Mine is Nano and I selected Uno and it caused me a day of grief because the Seeduino board looks like a Uno.
Tim W4YN

Tim
 

Mine did also, good luck!
Tim

John King
 

Jim:


Did some more testing on the Arduino and main board, trying to replicate the pulses shown in your photos on this topic.


I found that, with the AD9851 pulled from the main board, the pulses acted pretty much the same as your photos and had levels of about 5 v.  From that, I conclude that the Arduino is probably working as it should be.


I then replaced the AD9851 and powered it up.  At that point, I found that the D7 and W-CLK lines had multiple pulses as before but the levels on these lines were only around 0.2 v.  My guess is that something is holding these two lines to a low level.


Next step seems to be to try a new AD9851, unless you can think of another explanation.



Thanks for the help.


John, W5IDA

Tony Abbey
 

Is power getting to the DDS module? Powering it through the data inputs would overload them and reduce their o/p volts, although that does seem particularly low.
Tony

N5IB
 

I does point to something being amiss with the DDS module. So easiest course will be to replace it. You could use one of the cheaper 9850 ones for testing purposes.

I've been puzzling with what might have happened to it... I believe I understand it was working, then you removed the filter components... then it wasn't working. Just seems so unlikely to be able to damage it in that operation.

Jim, N5IB






---In PHSNA@..., <jpking8@...> wrote :

Jim:


Did some more testing on the Arduino and main board, trying to replicate the pulses shown in your photos on this topic.


I found that, with the AD9851 pulled from the main board, the pulses acted pretty much the same as your photos and had levels of about 5 v.  From that, I conclude that the Arduino is probably working as it should be.


I then replaced the AD9851 and powered it up.  At that point, I found that the D7 and W-CLK lines had multiple pulses as before but the levels on these lines were only around 0.2 v.  My guess is that something is holding these two lines to a low level.


Next step seems to be to try a new AD9851, unless you can think of another explanation.