[time-nuts] WWVB teensy BPSK early experiments

[jimlux]

On 10/31/20 11:42 AM, Bob kb8tq wrote:
> Hi
> 
> …..errr…..
> 
> Can you pull the clock oscillator off the Teensy board? (Yes, the soldering
> iron would be involved).
> 
> Will the clock input to the MCU accept something like 10 MHz? If so solder
> on a cable ….
> 
> At that point whatever the Teeny does is locked to the 10 MHz. If that comes
> from one of the $3 eBay OCXO’s, steer that with a DAC output … now you
> have a WWVB GPSDO.
> 
> Indeed, if the Teensy needs 28 MHz, then the OCXO will not be quite as cheap.
> 
> Bob
> 

I've tried this - It will run just fine, but *all the UART and USB 
speeds change*.  So, basically, the USB stops working, and you need to 
set your serial port to something like 112.8 * 10/28 (and it takes a bit 
of fiddling to get it to work right)..  I sort of cheated, and switched 
back and forth - signal generator to 28MHz, load and debug software, 
start it, then switch generator to 10 MHz.

And of course, all the functions that are time based, like delay() are 
the wrong length.

One could probably figure out a relatively few patches to the 
Teensyduino code base that would fix all this (clock rate is a variable 
- you can run the teensy at multiple clock rates, even with the same 
crystal)