[time-nuts] New Timestamping / Time Interval Counter: the TICC

Andrew Rodland andrew at cleverdomain.org
Thu Nov 24 02:49:00 EST 2016

On Wed, Nov 23, 2016 at 10:48 AM, John Ackermann N8UR <jra at febo.com> wrote:
> The TICC is implemented as a two-channel timestamping counter.  That means
> it can measure one or two low-frequency (e.g., pulse-per-second) inputs
> against an external 10 MHz reference, or it can do a traditional time
> interval measurement of one input against the other.  It can also measure
> period, ratio, or any other function of two-channel  timestamp data.  (And
> by the way -- multiple TICCs can be connected to yield 4, 6, 8, or more
> synchronized channels, though we haven't tested this capability yet.)

Very exciting, I will definitely be wanting one :)

There's *almost* a way to do the coarse timer counting with almost no
CPU overhead, but unfortunately the Arduino folks were terribly
inconsistent about which timer signals they decided to assign to
Arduino pins. Of the six external clocks for timers, they brought out
two (T0 and T5), and of the four input captures, they brought out two
(ICP4 and ICP5). If they had brought out T4 then with a little bit of
timer configuration you could use COARSE to clock TIMER4 and TIMER5 in
lockstep, run STOP_A and STOP_B to ICP4 and ICP5, and instead of
interrupting at 10kHz to increment PICcount, you would only have to
interrupt every 6.5536 seconds to increment the upper bits. Plus
handling the actual events of course. I find that very appealing, but
unfortunately, T4 is out of reach of a shield.


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