On 10/31/20 5:42 PM, paul swed wrote:
Jim
Thanks for the details. I took a serious look at popping the xtal out and
am afraid its a bit beyond me since there are 4 pads that need to be
heated. I have worked on very small stuff under the microscope. But this
seems problematic. I sort of thought all the bits would get upset. No free
lunch.
It's only hard if you want to save the crystal for later use <grin>.
Soldering iron right on the top of the crystal package, all 4 pads get
soft, scrape it off with the xacto knife.
Then, solder on the tiny wires from a coax pigtail. Blob of superglue to
keep it from breaking off.
I had about 50 of them, so if I broke it, I had more to try, but it
worked ok.
But, as noted, not particularly useful.
No matter not popping the xtal. Mainly because if anyone else did want to
build the magical solution it would be as bad as soldering lots of chips.
Super fine wires to very small pads.
But at least at the moment perhaps thats not critical to developing
something.
I did tinker with delay and will need to use a scope at this point to see
the effects.
Regards
Paul.
On Sat, Oct 31, 2020 at 7:35 PM jimlux <jim...@earthlink.net> wrote:
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)
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