Hi Jerry,
Thanks for this idea. I haven't considered that option.
When I have some time I'll try it out to see if it would work. If so it
could save us one I/O pin!
73 Allard PE1NWL
toggle quoted message
Show quoted text
On Tue, October 3, 2017 22:51, Jerry Gaffke via Groups.Io wrote:
One slight not-so-obvious advantage of this scheme: ??
?? Shorting that keyer paddle to case ground with your body would count as
key-down.
Could well be not-so-obvious advantages to using Allard's third pin scheme
that I am not seeing just yet.
Jerry
On Tue, Oct 3, 2017 at 12:40 pm, Jerry Gaffke wrote:
Not obvious the third pin is required for the capacitive touch keyer.
The dit and dah Nano input pins could also have open-drain outputs,
so drive the pin low and then release it to slowly float back up.
Read from the pin after it is released to see how long it takes
the pullup resistor to get the pin high again.
There should be plenty of web hits on how to do a bidirectional
open-drain
pin under Arduino.
Likely implemented as a tristate output, the output is enabled when
actively driving the pin low.
Allard PE1NWL