On 4/10/2014 11:38 PM, Hal Murray wrote:

==========

I can't recommend warmly enough the Discovery board from STM.
It sports a Cortex ARM M4F that can run at 180 MHz, has a native
IEEE compliant floating point core, 2MB flash and 256 kB RAM,
and a wealth of interesting peripherals on chip, TFT display touch
enabled included.  And at 23.52 USD is cheaper than a much
less powerful Arduino...

I implemented on it a fully featured SDR, without using any opsys,
talking directly to the bare metal using the Keil IDE/compiler.
A joy to use. Look here :

http://www.st.com/web/catalog/tools/FM116/SC959/SS1532/LN1848/PF259090

73  Alberto  I2PHD

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Hal
I sent you a message on the STM arm board and attached the speck sheet.
Its 215KB so it may not come through.
Just look up the STM discovery kit. Its $21 in the US.
Lots of good stuff counters IO and and such
Regards
Paul
WB8TSL

On Thu, Apr 10, 2014 at 5:38 PM, Hal Murray hmurray@megapathdsl.net wrote:

Take a look at http://www.pjrc.com/teensy/.

Regards,

Edésio

On Thu, Apr 10, 2014 at 02:38:10PM -0700, Hal Murray wrote:

Alberto did the job of reposting the information for me.
Thank you.
Hal take a look its impressive for $21.
Regards
Paul
WB8TSL

On Thu, Apr 10, 2014 at 6:02 PM, Alberto di Bene dibene@usa.net wrote:

On 04/10/2014 05:38 PM, Hal Murray wrote:

Another endorsement for a STM32 Discovery board from me. The F3 and F4
ones have plenty of peripherals to play with and they're cheap as dirt.

For a concrete example of how the kind of PPS capture that's being
discussed would pan out on STM32, here's mine:

https://github.com/mtharp/laureline-firmware/blob/master/src/ppscapture.c

The timers are 16-bit but I extend it to 64 bits in software. When the
timer rolls over I add 65536 to the software variable "mono_epoch". At
both the rollover and at the half-way mark I poll the timer-capture
peripheral to see if it captured a PPS. It's polled twice per period to
ensure that I can disambiguate whether the captured value came from the
current period or the previous one. The result is a 64-bit timestamp
from the free-running clock, and it's completely glitch-free and not
affected by interrupt latency in any way.

The same timer is also used as the base for the UTC clock, which is a
software-disciplined clock like you'd find in any OS kernel. That makes
it easy to compare the phase of the PPS captured to the nearest UTC
second and feed into the PLL. Not as interesting for a GPSDO where you
need to actually steer a hardware oscillator, but useful nonetheless.

BTW, its possible to extend timer to 64 bit using special feature of
ST32. Its when one timer (master), controlling the other timer(s)
(slaves). See following app. note, for example:

http://www.st.com/st-web-ui/static/active/en/resource/technical/document/application_note/CD00165509.pdf

Also, the examples which coming with peripheral library helps a lot !

I was using PIC and Freescale before. All my recent project is on ST32.
But instead of Discovery board I would prefer bare board with MCU from
auction site. JUst because its gives me more control. ;-)

--
WBW,

V.P.

First, the Arduino can count cycles just fine.  Look at the C code I
posted, it is all of about two dozen lines. It is intentionally simplistic
but seem seems to work. This discussion is about how I might be able to
remove about a half dozen lines.  I'd bet you a bunch the ARM would NOT be
simpler.  I would not go with the ARM process just to save having to count
cary-overs.

There is a great advantage to building a GPSDO in an ARM and a REALLY great
advantage to building on with a Beagle Board. Because you could also build
an NTP server on the same platform and time transfer to the NTP server
would be near perfect.  The BB could run a web server too and WiFi stack so
you could control the entire GPSDO/NTP Server with a wireless cell phone or
tablet.  You can remotely log in to your controller using SSH.  It's gross
overkill but the price is only about $50.    The Raspberry Pi is not a
whole loot different.

If you want a simple, low cost ARM development system there are three that
I'd look at.

1. The "teensy".  cost is $19 and it is the same size as the Arduino "mini"
   http://www.pjrc.com/store/teensy3.html
   Adafruit and Sparkfun also sell this same board.

2. The new Arduino Due is based on ARM and runs the same software
   environment as the AVR based Arduino.
   but of course is much more powerful and costs more.  Lots of support and
   all your Arduino code will mostly still work.
   http://arduino.cc/en/Main/ArduinoBoardDue

3. TI sells a "Launch Pad" at a very good price, about $13 and it is VERY
   well supported with training materials, software and so on.  I'm sure TI
   iix taking a loss on these.  They can't be making money at $13  This is a
   great value.
   http://www.ti.com/ww/en/launchpad/launchpads-tivac.html#tabs

On Thu, Apr 10, 2014 at 2:38 PM, Hal Murray hmurray@megapathdsl.net wrote:

--

Chris Albertson
Redondo Beach, California

Chris
Thats what I am saying the compute power is amazing even with arduinos.
I find it crazy to trip over limitations when this technology is available.
So yes I hope to use the STM board to solve the WWVB BPSK issue. At $21 its
a so what for me $ wise at least. I purchased 3 just because they do appear
pretty handy. The same with the launchpads. Now I went out to the TI site
and they have additional launch pad eval kits. All on nice boards just like
the STM evals.

Hope this helps Hal who started the thread.
I have said enough and on to that old Forth code.
Regards
Paul
WB8TSL

On Thu, Apr 10, 2014 at 8:11 PM, Chris Albertson
albertson.chris@gmail.comwrote: