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keypad response too slow
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freedom

Joined: 10 Jul 2011
Posts: 54


Posted: Tue Dec 23, 2014 5:05 am

here is some download link http://www.megafileupload.com/en/file/590854/4094-and-74595-LCD-with-3-wire-877A-zip.html http://www.mediafire.com/download/kh8162yud86dkcf/4094_and_74595_LCD_with_3_wire_877A.zip

Mike Walne

Joined: 19 Feb 2004
Posts: 1785
Location: Boston Spa UK

Posted: Tue Dec 23, 2014 10:12 am

Reply with quote

It's all down to timings, and working out what they are.

This section tells you how to set up:-

Code:

#define KBD_DEBOUNCE_FACTOR 33 // Set this number to apx n/333 where
// n is the number of times you expect
// to call kbd_getc each second

How many times per second do you expect to go round your loop?

These lines each take ~1.2ms

Code:

lcd_gotoxy(1,1);
printf(lcd_putc, "%c",k);

This one ~10ms

Code:

printf(LCD_PUTC,"%05ld ",dat);

With these lines in place:-

Code:

dat++;
lcd_gotoxy(10,3);
printf(LCD_PUTC,"%05ld ",dat);

You're going round at once in slightly over 11ms.
So your n is ~90.
In my book the calculation n/333 does NOT yield 33.

Now do you see where the problem is?

Mike

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