Hi all,
I recompiled after fixing a few bugs elsewhere in the program -
they had to do with confusing similarly spelled variables that
had different data types. The current discussion on coding styles
was timely; I prefixed all my variables with their data type and
resolved the problem in short order.

Friendly regards,

Patrick Murphy
James Valley Colony

Patrick Murphy wrote:
>
> Hi All,
> I'm trying to set up a menu on my serial 4x20 LCD (from NetMedia)
> and am wondering why my key press delay_ms(500) code isn't effective;
> in other words, after a button is pressed, I'm expecting the delay to
> take effect, but it doesn't; the program can loop hundreds of times
> instead of only once during that button press. I added some counters
> in-line to see this. I realize I am not otherwise debouncing the
> buttons; I'm simply looking at the port and acting on the state of
> the port; all PortD pins have external 10k pull-up resistors, so I'm
> assuming any activity on PortD is initiated by button presses.
>
> Here is what the menu looks like:
>
>         MAIN MENU
>         ->Run Automatically
>           Run Manually
>           Setup
>
> The bottom three lines of the LCD are menu items, and I'm reading
> three buttons on PortD, called Next, Previous and Select in a
> while loop. For example, when the Next button is pressed, the display
> is supposed to be updated - the select arrow moved to the next menu
> item or wrapped up to the first menu item. Monitoring the value of
> NextCtr in a watch window, I see that if I press the Next button 5
> times in about 2 seconds, and then stop the ICD, the NextCtr reads
> well over 1000; and the menu may or may not have been updated
> correctly.
>
> Below is the code fragment. I'm working in PICC, (PCM compiler 3.092)
> for the PIC16F877 using the MicroChip ICD.
>
> I am curious to know why the program can appear to bypass the delay
> routine and welcome any suggestions to improve my menu code or design.
> I think I am overlooking something basic, but I'm not sure what.
>
> Thanks in advance!
>
> Patrick Murphy
> James Valley Colony
>
> long NextCtr, PrevCtr;
> NextCtr = 0; // Count the number of times this portion of code is active.
> PrevCtr = 0; // Also count in the Previous Button code.
>
> pspmode = 0;  // Set up PortD
> PORTD = 0xFF; // Make PORTD inputs
> TRISD = 0xFF;
> ArrowLine = 1; // Current LCD line counter
>
> // Loop while waiting for user input: Next, Previous, or Select buttons.
> while(MenuState == MainMenu0)           //Monitor lower 5 PortD inputs
> {
>         PDButtons = PORTD;
>         PDButtons = ~PDButtons; // Invert so button pressed is now high
>         switch (PDButtons)
>         {
>                 case 0x01:  // Select Button Pressed: PortD0. Selected new menu.
>                         porta1 = 1;  // Porta1 LED for debugging. No delay necessary.
>                         if (ArrowLine == 1)
>                                 MenuState = Automatic1;
>                         else if (ArrowLine == 2)
>                                 MenuState = Manual2;
>                         else if (ArrowLine == 3)
>                                 MenuState = Setup3;
>                         break;
>                 case 0x02: // Next Button Pressed: PortD1. Move arrow down or wrap.
>                         porta2 = 1;  // Porta2 LED for debugging.
>                         NextCtr++;
>                         if (ArrowLine < 3)
>                         {
>                                 ArrowLine++;
>                         }
>                         else
>                         {
>                                 ArrowLine = 1;
>                         }
>                         printf(ser_char, "  ");
>                         ser_lcd_cursor_pos(0, ArrowLine); // col, line
>                         printf(ser_char, "->");
>                         ser_lcd_cursor_pos(0, ArrowLine); // col, line
>                         delay_ms(500);
>                         break;
>                 case 0x04: // Previous Button Pressed: PortD2. Move arrow up or wrap.
>                         porta3 = 1;
>                         PrevCtr++;
>                         if (ArrowLine > 1)
>                         {
>                                 ArrowLine--;
>                         }
>                         else
>                         {
>                                 ArrowLine = 3;
>                         }
>                         printf(ser_char, "  ");
>                         ser_lcd_cursor_pos(0, ArrowLine); // col, line
>                         printf(ser_char, "->");
>                         ser_lcd_cursor_pos(0, ArrowLine); // col, line
>                         delay_ms(500);
>                         break;
>                 case 0x08: // Up Button Pressed: PortD3. Not used in this menu.
>                         porta5 = 1;
>                         delay_ms(100);
>                         break;
>                 case 0x10: // Down Button Pressed: PortD4. Not used in this menu.
>                         portb0 = 1;
>                         delay_ms(100);
>         }// switch
>         porta1 = 0; Turn off debugging LED's
>         porta2 = 0;
>         porta3 = 0;
>         porta5 = 0;
>         portb0 = 0;
> } // while(MenuState == MainMenu0)
>
> void delay_10us(byte t)
> // provides delay of t * 10 usecs (4.0 MHz clock)
> {
> #asm
>       BCF STATUS, RP0
> DELAY_10US_1:
>       CLRWDT
>       NOP
>       NOP
>       NOP
>       NOP
>       NOP
>       NOP
>       DECFSZ t, F
>       GOTO DELAY_10US_1
> #endasm
> }
>
> void delay_ms(long t)   // delays t millisecs (4.0 MHz clock)
> {
>    do
>    {
>      delay_10us(100);
>    } while(--t);
> }
>
> --
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--
http://www.piclist.com hint: The PICList is archived three different
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