Stuck on porting code to 18F4520

[HenrikOlsson]

Hi,
There are only 7 bits in your example, you want to set it to use the instruction clock as the source, I think this shoukd do it.

T0CON = %11000111  'TMR0 ON, 8bit mode, instruction clock as source, prescaler assigned to TMR0, 256:1 ratio

When you run the PIC at 20MHz but tell the compiler it's being run at 48MHz all the timings will be off by a factor of 2.4.
A PAUSE 10 will actually be 24ms instead of 10ms. The same thing happens with ALL other commands that relies on software timing, including LCD-out. The fact that the display does NOT work when the compiler uses the correct OSC value to calculate the timings suggests that the LCD is slower than "normal". Try increasing the

DEFINE LCD_COMMANDUS 2000        ' Command delay time in us 
DEFINE LCD_DATAUS 50             ' Data delay time in us

And add a bit of delay at the start of the code to allow the LCD to start up properly.

/Henrik.

[Scampy]

Hi Henrik,

I already had the LCD delays in place, but added an initial two second pause and clear before the main code. I now have the time displayed on the LCD using the following code

ASM 
  __CONFIG    _CONFIG1H, _OSC_HS_1H
  __CONFIG    _CONFIG2L, _PWRT_ON_2L  
  __CONFIG    _CONFIG2H, _WDT_ON_2H & _WDTPS_512_2H
  __CONFIG    _CONFIG3H, _MCLRE_ON_3H & _LPT1OSC_OFF_3H & _PBADEN_OFF_3H  
  __CONFIG    _CONFIG4L, _LVP_OFF_4L & _XINST_OFF_4L
ENDASM

DEFINE  OSC 20  ; 48 was old config settings 18F4520, 20mhz crystal
ADCON1 = $0F
clear


DEFINE LCD_DREG  PORTB           ' LCD Data port
DEFINE LCD_DBIT  0               ' starting Data bit (0 or 4)
DEFINE LCD_EREG  PORTB           ' LCD Enable port
DEFINE LCD_EBIT  5               '     Enable bit  (on EasyPIC 5 LCD)
DEFINE LCD_RSREG PORTB           ' LCD Register Select port
DEFINE LCD_RSBIT 4               '     Register Select bit   (on EasyPIC 5 LCD)
DEFINE LCD_BITS  4               ' LCD bus size (4 or 8 bits)
DEFINE LCD_LINES 4               ' number of lines on LCD
DEFINE LCD_COMMANDUS 2000        ' Command delay time in us 
DEFINE LCD_DATAUS 50             ' Data delay time in us 

LED var portA.7



CMCON=7                'all digital 
T0CON = %11000111
INTCON=0               'interrupts off
'**********************************************************
HzTimer VAR Word         '1/2 second counter (2 Hz)    
HH VAR Byte  ' Hours 0-23
MM VAR ByTE  ' Minutes 0-59
SS VAR Byte  ' Seconds 0-59
col VAR Byte  ' colon 1=on, 0=0ff

HzTimer=$7A12        'for 1/2 Sec
HH=12:MM=0:SS=0:col=0 'initial conditions (12:00 O'clock noon)
'**********************************************************

LCDOUT $FE,1:FLAGS=0:PAUSE 250:LCDOUT $FE,1:PAUSE 250 ' Initialize LCD 

Main:

ClockLoop: IF intcon.2=0 THEN ClockLoop	'Poll for TMRO overflow
INTCON.2=0 ' Clear TMRO overflow flag

HzTimer=HzTimer-$1000	'decrement timer count

IF HzTimer < $1000  THEN
    IF Col=10 THEN    ' update time'
        SS=SS+1
        LED =0    ' Turn off GP1
        IF SS=60 THEN   ' minute
            SS=0 
            MM=MM+1
            IF MM=60 THEN    ' hour            
                MM=0
                HH=HH+1
                IF HH=24 THEN HH=0
                IF HH=20 then LED = 1    ' Turn on GP0 at 8:00pm
               LED =1    ' Turn On  GP1 for 1 second on the hour
            ENDIF                           ' Adjust these to meet your needs
            if MM=15 then LED = 0        ' Turn off GP0 at 8:15pm  
        ENDIF
    ENDIF
    Col=Col+1

    HzTimer=HzTimer+$7A12	' Add 0.5 seconds to count
ELSE
    ' Do something here but must be less than 65.5 mSec
ENDIF
      if Col=11 then 
    Col=1
    endif
   
    LCDOut $FE,$D4,#HH,":",#MM,":",#SS
    
GOTO  Main 'forever
' **************************************************************
END

I changed one of the defines in the config as it was using the PLL option so setting this to just HS resolved the OSC setting.

The display is crude and needs some tiding up to overdraw double digits (the 9 in 59 is left on the screen so when it counts 1,2,3 seconds it displays 19,29,39 etc) but I can work on that. I just hope I have enough time between the overflows to do the rest of the code, such as fade in LEDs over a period of time etc.

Thanks for your help. - here's the code I'm now using which works on an 18F4520 with a 20mhz xtal



Thanks once again for your help...

[Scampy]

Its been a long day....

    IF HH = 20 and MM = 0 then 
    LED = 1  
    endif
    lcdout $FE,$80,#LED

for some reason when the LCD displays 20:00:00 the LED value still remains 0 and the LED fails to light

Time for bed... now even the simple stuff won't work !