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 On Tue, Nov 10, 2020 at 10:43 AM paul swed <[email protected]> wrote: > Graham that is the alternate approach. The new suggested KD2BD vcTCXO works > very well. Its 10 MHz and readily available. But then the old divider > chains are needed. The KD2BD method works well if you have plenty of > solder. > First mixer is 50 KHz LO. Result 10 KHz IF. > 10 KHz IF gain > Second Mixer is a 10 KHz LO results in a 0 Hz IF. > But the products are actually phase offset and bit. > The above comments are seriously over simplified. > Having built the KD2BD receiver I am interested in a low solder solution. > :-) > Really have to do far more experimentation. The teensy is very powerful. > Regards > Paul > > > On Tue, Nov 10, 2020 at 12:56 PM Graham / KE9H <[email protected]> > wrote: > > > Paul: > > > > It might be easier to relegate that function to hardware. > > A simple TC-VCO that drives the sampling clock for the ADC and is > steerable > > for frequency/phase lock from the CPU would allow you to build a > > synchronous receiver without working about locking the CPU clocking > system > > to anything. > > > > --- Graham > > > > == > > > > --- Graham > > > > On Mon, Nov 9, 2020 at 8:06 PM paul swed <[email protected]> wrote: > > > > > No time to experiment the last few days as the weather has been great > and > > > have to get outside stuff done. That said trying to tease apart how to > > > create a lockable NCO in the teensy. > > > Its not clear to me that I can create a sine wave oscillator and drive > > that > > > out to a pin to see stability and adjustment effects. It can be done by > > > mixing with another internal signal and measuring the output. But my > > > preference would be direct measurement. > > > With respect to sine and cosine. It seems a second oscillator and a > third > > > oscillator that is 90 degrees out can be created. Supposedly these > would > > be > > > locked. (To be proven) > > > Regards > > > Paul > > > > > > > > > On Sun, Nov 8, 2020 at 7:59 PM John C. Westmoreland, P.E. < > > > [email protected]> wrote: > > > > > > > Hello Graham and Fellow Time Nuts, > > > > > > > > I did what Paul had mentioned as well - and that appeared to clear up > > the > > > > immediate screen issues but I will > > > > insert a termination resistor as well as Graham has suggested. > > > > > > > > I looked on the PJRC forum as well - and it appears there has been a > > lot > > > of > > > > discussion and development regarding > > > > the enhancement of the performance of these TFT displays - also - > > > there's a > > > > beta version of the arduino libraries - > > > > Teensyduino 1.54 Beta #4 - > > > > https://forum.pjrc.com/threads/64303-Teensyduino-1-54-Beta-4 - take > a > > > look > > > > at that > > > > for those that are experimenting with this platform. > > > > > > > > As far as my current setup - in the wee hours today - the WWVB signal > > was > > > > coming in very strong - my HPSDR rig > > > > using the Clock tool from Multipsk was decoding every minute - the > > Clock > > > > programs' PLL was solidly locked. > > > > > > > > I noticed for the Teensy4WWVBsdr code it appeared to be in sync with > > > WWVB - > > > > it was decoding either a minute or > > > > the hour apparently correctly - but it was shifted - meaning say for: > > > > > > > > 2:38:00 AM it decoded 2 as the minute - which was incorrect but > correct > > > for > > > > another time position > > > > > > > > or, for the hour it would say 8 as hour. This makes me think > obviously > > > for > > > > some reason the positions are being > > > > shifted in an otherwise somewhat successful decode attempt. > > > > > > > > I am using the Teensy 4.1 - I need to check all of the libs to make > > sure > > > > nothing incompatible is possibly taking place. > > > > > > > > I've been informed also the antenna from Stormwise is on the way. > > > > > > > > Thanks again Graham - KE9H - for helping out on this. > > > > > > > > 73's, > > > > John > > > > AJ6BC > > > > > > > > > > > > On Sun, Nov 8, 2020 at 8:02 AM Graham / KE9H <[email protected]> > > > > wrote: > > > > > > > > > John W: > > > > > > > > > > Regarding your Teensy WWVB receiver display issues. > > > > > The Teensy does not have a source termination resistor on the SPI > > > clock. > > > > > Add a 50 Ohm resistor (value not critical, anything from 33 to 75 > > will > > > > > work) in series with the SPI Clock signal, as physically close to > the > > > > > Teensy as practical. > > > > > This totally cleared up all of my display issues. > > > > > > > https://www.analog.com/media/cn/training-seminars/tutorials/MT-097.pdf > > > > > Source termination resistors provide a source resistance to absorb > > the > > > > > reflection of fast edges off the slave device input, reducing all > the > > > > > bouncing and wiggles on the rising and falling edges of signals, > > > > > particularly important/beneficial on clock signals. > > > > > > > > > > --- Graham > > > > > > > > > > == > > > > > > > > > > > > > > > On Wed, Nov 4, 2020 at 10:55 AM John C. Westmoreland, P.E. < > > > > > [email protected]> wrote: > > > > > > > > > > > Paul/Chris, > > > > > > > > > > > > Also - in addition to the white screen, I get this sometimes > after > > > > > running > > > > > > for a while - have you guys seen this? > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > https://user-images.githubusercontent.com/2308903/98118247-cd4c7b00-1e5f-11eb-8510-aa1ed0beba52.jpg > > > > > > > > > > > > 73's, > > > > > > John > > > > > > AJ6BC > > > > > > > > > > > > > > > > > > To unsubscribe, go to > > > > > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > > > > > and follow the instructions there. > > > > > > > > > > > _______________________________________________ > > > > > time-nuts mailing list -- [email protected] > > > > > To unsubscribe, go to > > > > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > > > > and follow the instructions there. > > > > > > > > > _______________________________________________ > > > > time-nuts mailing list -- [email protected] > > > > To unsubscribe, go to > > > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > > > and follow the instructions there. > > > > > > > _______________________________________________ > > > time-nuts mailing list -- [email protected] > > > To unsubscribe, go to > > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > > and follow the instructions there. > > > > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
