Topics

I2C interface tip (for the WB6OGD additions)

Tony Jaques
 

Hi all,
It is quite a while since I last left a message for the
group. I see that my previous offerings were from "Jaques
Anthony" but I found it quite imposible to get into this
group from groups.io. I had to subscribe again - so I am
now a new user!
For a long time I have been meaning to follow up the
excellent PHSNA by trying WB6OGD, Gary's additions which
enable it to be used with a 'scope to make "tweaking"
circuits that much easier.
Oh indeed it does. Thank you very much Gary, and well
done.
Anyone else contemplating the same route might be helped
by learning of a problem that I had to overcome. The
additions were obviously working, but with no information on
the 20 x 4 LCD issuing commands was not easy!
It eventually dawned on me that the I2C interface board
on the display that I bought used an PCF8574A chip. That
uses address 3Fh by default. (The "helpful" data sheet that
came with the display told me that it used 27h!). Gary's
software is designed to talk to the PCF8574 which does indeed
operate at 27h.
So, if you get no display, the fix is easy of course;
In Gary's PHSNA_VB.ino just change the line
LiquidCrystal_I2C lcd(0x27,20,4);
to
LiquidCrystal_I2C lcd(0x27,20,4);

I was wondering if anyone has tried to make the addition
to the later versions of the Windows software. If not then
- unless Gary objects - I might have a go at it.

Note that if you order the I2C interface modules, don't
use the Image of the board as a guide. It may show the /A
chip, but you will almost certainly be sent the non A version!

Tony (G3PTD).

Tony Jaques
 

Oops!
That line change should have been to 0x3F,20,4 of course.
Tony...

wb6ogd
 

Hi Tony,
  Good to hear someone else tried it, despite a few others interest, I think you
and I are the only ones to use it.

By all means have at the code.  Nick was nice enough to let me modify his and
post my changes.  All the tricky, good code is his.

Not sure what you mean by Windows changes.  I set it up so that the interface to
Nick's Windows program should be un-affected, the Windows code thinks it
is talking to an un-modified PHSNA.  My PHSNA is my go-to instrument, I don't
have a commercial RF generator.  Been an exceptionally useful tool, thanks to
the creators!  Tuning filters with a scope has been very useful to me.  And being
able to just dial up a signal frequency with no PC needed is the normal mode.

Sorry about the address change.  I have been stung by that myself.
You can program a "search", keep throwing it addresses and write that address
to the LCD, when it shows up, you know the address.

If anyone wants any code changes, let me know.  I actually have more in mine,
DDS as well as Si5351 (to allow >60Mhz), etc.
73,
Gary
WB6OGD

On 7/4/2018 8:46 AM, Tony Jaques wrote:


Hi all,
 It is quite a while since  I  last  left a message for the
group. I see that  my  previous  offerings were from "Jaques
Anthony" but I found  it  quite  imposible  to get into this
group from groups.io. I had  to  subscribe  again -  so I am
now a new user!
  For a  long  time I have  been  meaning to  follow up the
excellent  PHSNA by trying  WB6OGD, Gary's additions  which
enable  it  to be  used  with a 'scope  to  make "tweaking"
circuits that much easier.
 Oh indeed it does.  Thank  you  very  much  Gary, and well
done.
 Anyone else contemplating the  same  route might be helped
by learning  of  a  problem  that  I  had  to  overcome. The
additions were obviously working, but with no information on
the 20 x 4 LCD issuing commands was not easy!
  It eventually dawned on me  that  the I2C interface board
on the display that  I  bought  used  an PCF8574A chip. That
uses address 3Fh by  default. (The "helpful" data sheet that
came with the display told me that it used 27h!). Gary's
software is designed to talk to the PCF8574 which does indeed
operate at 27h.
  So, if you get no display,  the  fix  is easy of course;
In Gary's PHSNA_VB.ino just change the line
 LiquidCrystal_I2C lcd(0x27,20,4);
 to
 LiquidCrystal_I2C lcd(0x27,20,4);

  I was wondering if anyone has  tried to make the addition
to the later versions of the  Windows software.  If not then
- unless Gary objects - I might have a go at it.

   Note that if you order the I2C interface modules, don't
use the Image of the board as a guide.  It may show the /A
chip, but you will almost certainly be sent the non A version!

Tony  (G3PTD).


Tony Jaques
 

Hi Gary,
Sorry for the delay in my reply; Computer problems. How unusual!
I do have two signal generators for up to 500MHz, and a Wavetek
sweep generator for up to 1000MHz, and a spectrum analyser, also
for up to 1000MHz, and an AIM Vector analyser, but even so I still
reach for my PHSNA first. It' the best piece of test gear I have ever
built.
Now for an admission: I did not want to modify my PHSNA to try
your addition (and indeed, could not for lack of panel space), so
having a DDS60 and an Arduino NANO doing nothing I built that
version for the purpose. (I already had a separate 8307 stand alone
demodulator on hand to feed the 'scope.)
But I did not take the 8307 output back to the Arduino. It was not
needed for the test. So I have not actually tried to use it in the original
PHSNA mode.
My assumption that later versions of the software needed a
different version of your PHSNA_VB.ino arose from "to be used with
his Windows C# version 1r40 (1.40)" in your notes". Of course, now
I think about it that assumption looks pretty silly. And if I had actually
tried to use it in "original" mode I would have discovered that for myself.
Sorry Gary.

Tony...