[time-nuts] Frequency Counter Choice

[Ben Bradley]

On Fri, Oct 23, 2020 at 9:14 AM jimlux <jimlux at earthlink.net> wrote:
> ...
> to be set - for instance, Arduinos work that way:
>
> digitalWrite(pin#, HIGH)
>
> I think GPIB would still work if you had to do 8 digitalWrite() calls,
> then a final digitalWrite() call to assert DAV.
>
>
> I suspect that for a number of Arduino type processors, there is a way
> to write or read all 8 at once, assuming you were clever enough to pick
> the right pins to use.

It's easy once you figure out which I/O ports you're using. I traced
the AVR pinout and Arduino Mega 2560 schematic to translate between
AVR ports and Arduino I/O pin numbers and to find the port I wanted to
use. Googling found the port names that you can directly read from and
write to in Arduino C/C++ code, as opposed to using the digitalwrite
function for each bit. Here I used DDRC and PORTC:
http://blog.freesideatlanta.org/2017/02/a-capacitive-touch-janko-keyboard-what.html