Re: [Lcd4linux-devel] Re: I2C Keyboard implementation

[Michael R. <re...@eu...>]

Hi Luis,

> Ok, but we need to 'spinlock' around key polling because writing to
> the LCD and reading the buttons uses the same 8 bit bus...

No problem: thread.[ch] already provides mutex functions.

But I see another problem, which I didn't think of: If your separate
thread rises an event/signal, I have to pass this to the main thread :-(

>>A handler will be a Evaluator expression.

> Ok, something like a plugin then?
The 'handler' is not a plugin, but an expression (which can call
functions from plugins, of course).

> We will need to have the output to the LCD and the input from the keys
> in the same driver because of that 'spinlock' issue.
Right. There will be a helper file "event.c", which will provide
functions to raise an event. There will be "event classes", one of them
being a keyboard event. A code fragment from your key polling thread
could look like this:

while (1) {
   mutex_lock(my_mutex);
   key = poll_keypad();
   mutex_unlock(my_mutex);
   if (key >0) {
      now=time();
      if (now-last > KEYPAD_DEBOUNCE_TIME) {
         event_raise (EVENT_KEY, key)
      }
      last=now;
   }
   usleep (keypad_delay);
}

I'm not shure if debouncing is that easy :-)

Probably there should be a difference between key press and key release.

> I was afraid of that... unfortunately i have NO idea how to do it
> properly...
see above :-)


bye, Michael

-- 
Michael Reinelt <re...@eu...>
http://home.pages.at/reinelt
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