On Mon, Apr 24, 2017 at 10:13 AM, Bob kb8tq <kb...@n1k.org> wrote: > Hi > > Some of the process below is “not trivial”. One example: > > You have a “gate” from the GPSDO and a “signal” from somewhere else. If you > want the STM to do the whole thing, the “gate” pin needs to get the job > done in > X +/- 1 cycles of the “signal” pin. Delay X (if it’s consistent) isn’t a > problem. Having a > > +/- 1 cycle delay *is* a problem. The interrupt servicing structure in > the MCU > may or may not be able to hit things +/- 10 ns or even +/- 100 ns. > Sometimes a > “lower power” MCU with simple code is better at this than a multi core > gizmo running > a high level operating system.
-- C The STM32 is in fact a low level micro controller that does not run an OS. The chips contain counters and other hardware so most of the real-time stuff is not done in software. You need to set this up so the on-chip hardware outside of the CPU is used. There are two basic types of ARM computers, the "Cortex A" is what is in your phone and these have multi cores, GHz class clock speeds, gigabytes class memories and run an OS. The other is ARM "Cortex M". These are much smaller and run on about 100 uA of current with clocks about 100 MHz and kilobyte class memories and don't support running an OS. These are used in embedded applications such as the throttle control in your car or a high end battery charger. These cost about $1 each and the physical chip is about 3/8 inches square. I buy them quality one as a "Nucleo" board for about $12. It is like an Arduino but about (literally) 100X better specs and half the cost. About the same physical size. But for this counter project I'd use a generic STM32 board from eBay. They sell for about $2 shipped Take a look at this device. It has a lot of power. It can even be programmed using the Arduino IDE or the gnu toolchain and others. You can't beat the price or the size. ...ebay.com/itm/New-STM32F103C8T6-ARM-STM32... <http://www.ebay.com/itm/New-STM32F103C8T6-ARM-STM32-Minimum-System-Development-Board-Module-For-Arduino-/272546586490?hash=item3f750adf7a:g:RakAAOSwUKxYlyHv> hris Albertson Redondo Beach, California _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.