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keypad output no stable

 
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williamho
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keypad output no stable
PostPosted: Wed Jun 29, 2005 5:11 am     Reply with quote
Hi, I have connected 7 pins from 3x4 keypad to portD1 to 7.
D4,5,6,7 connected to rows with 10K pullup resistor.

I can get reading from RS232 but reading not stable:-

for example : row 1 with '1', '2' and '3'.
Whenever I press key '1', output will change rendomlly 1 or 2 or 3.
If i press any key from row 2 ('4','5' and '6'), output appeared to be 4 or 5 or 6.

what is wrong with the code or the hardware connection?

Thanks


Code:
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=20000000)
#use rs232(baud=9600,  parity=N, Bits=8, xmit=PIN_C6, rcv=PIN_C7,stream=COM_1)
#include <can-18xxx8.c>
#include <lcd.c>
#include <kbd_mdy.c>



void main()
{
    kbd_init();

   printf("ready");

   while(TRUE) {
        k=kbd_getc();
      if(k!=0)
      {
      putc(k);
      }
   }
}
Ttelmah
Guest
PostPosted: Wed Jun 29, 2005 8:22 am     Reply with quote
Without seeing your keyboard code, nobody can help...
Presumably you have modified the standard 'kbd.c'?.
The pull up resistors need to be on the input lines, not the lines that drive the keyboard. The way you are talking about three possible outputs being generated, suggests that there are four drive lines, and three inputs?. If so, put the resistors on the other lines.

Best Wishes
Guest
PostPosted: Wed Jun 29, 2005 6:45 pm     Reply with quote
thanks, I will reconnect the pullup resistor again.
Guest
PostPosted: Wed Jun 29, 2005 8:29 pm     Reply with quote
Quote:
I can get reading from RS232 but reading not stable:-


Wrong clock value?

Are you using the internal or a external oscillator? Sounds like your clock may be out, causing the problem you describe.

If using the internal osc, try using a crystal instead see if it clears it up.
Guest
PostPosted: Wed Jun 29, 2005 8:30 pm     Reply with quote
Quote:
I can get reading from RS232 but reading not stable:-


Wrong clock value?

Are you using the internal or a external oscillator? Sounds like your clock may be out, causing the problem you describe.

If using the internal osc, try using a crystal instead see if it clears it up.
treitmey



Joined: 23 Jan 2004
Posts: 1094
Location: Appleton,WI USA

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PostPosted: Thu Jun 30, 2005 7:59 am     Reply with quote
As for the RS232, If you have a ground in common to PC and circuit under test the serial will be much more stable.

I don't know if you can change your circuit or not.
But if you can, I like this circuit.
http://a330.g.akamai.net/7/330/2540/20050519160504/www.edn.com/contents/images/601828f1.pdf
note that is has a irq pin. That way you don't have to poll all the time. Just set a flag on irq. read the keypad when flag is set. It also has a 2.2uF cap that adds a hardware debounce.
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