[time-nuts] WWVB teensy BPSK early experiments

[John C. Westmoreland, P.E.]

Hello Time Nuts,

Paul, the wiring harness I made is longer than 6" - not by much - but I'll
shorten those and see if it clears it up.
I thought the same thing - maybe the display could be flaky - or maybe
strange things can happen too if in
the software the touch screen part is enabled but the wiring isn't there -
not sure.  But, can't rule that out right
now - will double check to see if in the code the touchscreen part is
running or not.

I'm also checking the CHIP_MIC_CTRL register in my code - I wanted to see
if disabling the micbias block could work -
the register can be written/changed - in the control_sgtl5000.cpp file - in
the micGain() function -
change:

return write(CHIP_MIC_CTRL, 0x0170 | preamp_gain)
to
// return write(CHIP_MIC_CTRL, 0x0070 | preamp_gain)
   // attempt to disable mic bias block --- aj6bc/jcw
or
return write(CHIP_MIC_CTRL, 0x0000 | preamp_gain)

If you want to read that back - then:
in control_sgtl5000.h - move:
 unsigned int read(unsigned int reg); // removed from protected:

from protected to public:

and in your code you can call something like:
// check value of mic control register:
  mic_ctl_regval = sgtl5000_1.read(CHIP_MIC_CTRL);
  Serial.printf("\r\nMic Control Register (ADDR 0x002A) = 0x%x \r\n",
mic_ctl_regval);

you may need to:
#define CHIP_MIC_CTRL      0x002A // microphone gain & internal microphone
bias
at the top of your file.

I'm still not sure if that's OK to do - I think the chip is looking for a
feedback on that possibly and it doesn't really buy you much.
I'm still testing all of that now - maybe just being able to read that
register back is worth something.

I received the antenna from Stormwise and am using in an inductive coupling
mode with the Teensy set up - and I got the first
successful decode using the code from Chris Howard - so good job there
Chris.  Gotta admit it's pretty cool watching the inductive
coupling effect work.

It's apparent I still have some noise - I haven't done a lot yet for
shielding anything, so I obviously need to do that - good news
obviously is finally seeing some good decodes coming in.

Of course, this is in the quiet wee-hours but WWVB is pretty strong at this
time at my QTH.

I'll work on ways to reduce noise next.

73's,
John
AJ6BC






On Wed, Nov 11, 2020 at 12:21 PM paul swed <paulswedb at gmail.com> wrote:

> I kind of wonder if you don't have a flakey display. I did not add the
> terminating R and everything has always worked fine on the display. After I
> quit using the 3" jumper cables to the audio card and stacked the modules,
> the audio worked correctly.
> My display is on a set of 6" jumpers and has been stable from day one.
> Though currently the display isn't connected since I am experimenting with
> various modules in the teensy.
> Regards
> Paul
> WB8TSL
>
> On Wed, Nov 11, 2020 at 10:47 AM Graham / KE9H <ke9h.graham at gmail.com>
> wrote:
>
> > John:
> > I suggest you try Chris Howard's
> > https://github.com/chris-elfpen/Teensy4WWVBsdr
> > You might have to adjust the I/O pins for Teensy 4.1 vs 4.0
> > I am having no problems with the display once I put in the source
> > termination resistor.
> > Been running for multiple days, so far.
> > --- Graham
> >
> >
> >
> > On Tue, Nov 10, 2020 at 9:45 PM John C. Westmoreland, P.E. <
> > john at westmorelandengineering.com> wrote:
> >
> > > Hello Time Nuts,
> > >
> > > I've been running some tests - I just had the screen 'white-out'
> problem
> > > happen again - I have a termination resistor on the SCK line (pin 13 on
> > the
> > > Teensy 4.1) -
> > > so it appears this is related to the TFT screen updates - maybe a pixel
> > > write going out of bounds.  The Teensy is still running - but the
> screen
> > > can't be read.
> > >
> > > Note the current code I'm testing is here in case anyone is interested
> -
> > > it's from the PJRC forum:
> > > https://github.com/jwestmoreland/el_supremoWWVBsdr
> > >
> > > 73's,
> > > John
> > > AJ6BC
> > >
> > >
> > >
> > _______________________________________________
> > time-nuts mailing list -- time-nuts at lists.febo.com
> > To unsubscribe, go to
> > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> > and follow the instructions there.
> >
> _______________________________________________
> time-nuts mailing list -- time-nuts at lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>