[time-nuts] WWVB teensy BPSK early experiments

[Graham / KE9H]

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. <
john at westmorelandengineering.com> 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
>
>
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