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lcd_getc returns nothing

 
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aasief



Joined: 12 Feb 2009
Posts: 12
Location: cape town

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lcd_getc returns nothing
PostPosted: Tue Jul 07, 2009 7:18 am     Reply with quote
Hey all

I'm using a keypad and lcd display with a pic 877. The keypad section works and the lcd works too except when I do the lcd_getc function, it just returns a cursor character. I sort of modified the LCD.c driver to work on port_d and it works but I think maybe I'm missing something with the getc function. Here is the lcd driver code.

Code:

////////////////////////////////////////////////////////////////////////////
////                             LCD420.C                               ////
////            Driver for common 4x20 LCD modules                      ////

++++++++++++++++++
Code deleted.
Reason: Forum Rule #10
10. Don't post the CCS example code or drivers

-- Forum Moderator
++++++++++++++++++

And in my main, when the following function is called, The lcd has characters at the location but nothing gets returned



Code:

void calculate()
{delay_ms(50);
      agetenschar=lcd_getc(8,2);//It doesnt return this char when there is a character at that position
      agetens=agetenschar-'0';  //convert asci to integer
     // agetens=agetens*10;
      //ageunitsk=lcd_getc(9,2);
      ageunits=ageunitsk-'0';
     // ageunits=ageunits*1;
      //age=agetens+ageunits;
      //calcage=age*2;
printf(lcd_putc"\f");
lcd_gotoxy(1,1);
printf(lcd_putc"agetenschar=%c",agetenschar);
lcd_gotoxy(1,2);
printf(lcd_putc"agetens=%d",agetens);

}

When i simulate in proteus, i get an error msg stating that the hd44780 driver was busy while trying to read

Has anyone ever had this problem before?
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Tue Jul 07, 2009 1:07 pm     Reply with quote
Because you're using Proteus (and most of us don't have it), there is no
way for us to read the data sheet on the LCD simulation. Or if there was,
how do we know what version of the LCD simulation you have ? Some
versions might not support reading the LCD.

Also, your test program is too complicated. To test the lcd_getc()
function, you should have a very short program in main() that sets
the cursor to (1,1), and writes a character there, such as 'A'. Then
call lcd_getc(1,1) to read it. Display the character that was read on
a terminal window using the PIC's UART. Make sure you put a while(1)
statement at the end of main() to prevent the PIC from going to sleep.
aasief



Joined: 12 Feb 2009
Posts: 12
Location: cape town

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Solved it
PostPosted: Wed Jul 08, 2009 2:43 am     Reply with quote
I solved it,
I just had to test the busy flag on the lcd with a
Code:

char lcd_getc( BYTE x, BYTE y) {
   char value;

    lcd_gotoxy(x,y);

    while ( bit_test(lcd_read_byte(),7) ); // wait until busy flag is low
    lcd.rs=1;
    value = lcd_read_byte();
    lcd.rs=0;
    return(value);


Thanks anyway PCM
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