Re: Keypad for Raduino...?
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Mark? N1VQW
I built a similar SNA, but control it via USB/tty link from a Raspberry-Pi.?
The keypad idea of using a single ADC input to decode keystrokes seems
intriguing to me.? This morning I set up the code so it uses a range of voltage
values for each key, and added a time delay for debounce.? using a voltage
range window seems to give me latitude enough for using standard value
resistors in the R-matrix.? Initially I set up the code to just show the value as
each key was pressed, then rewrote it to use those values as targets.?
I divided the difference between voltage values for each key by 2 and used
that to generate the tests for each key.? Code is not efficient yet as it is just a
bunch conditionals but once it is working I can go back and make it pretty.?
Next question is how much will RF affect the keystroke voltage readings?
This activity is generating some interesting thoughts about possibilities for a
new Raduino design...with OLED display, Keypad, Rotary Encoder, RTC,
Si5351a, and more.
Arv? K7HKL
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On Sun, Jun 24, 2018 at 11:34 AM Mark Pilant < mark@...> wrote: Hi Arv.
I used a similar keyboard for a Scalar Network Analyzer I built.? (Before I
found out about the PHSNA :-)? It turned out to work very well.? I did run
into a few issues worth mentioning.
Make sure you have some form of switch debouncing (software or hardware) as
part of the design.? I had both in my design.? ?Also, make sure you take into
account the resistor tolerances when determining the analog value for any
given key.? (Part of my SNA design was a set of calibration tasks, one of
which was the keypad.)
I'm building a uBitx with a TFT, and may include a soft keypad to augment the
encoder.? (If I can find the time... too many projects :-)
73
- Mark? N1VQW
BTW, feel free to look at the SNA code:
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