Unable to use the number 8 in DATA statement

[dbachman]

Whenever I run this in my 18F1320, I can read the data statement just fine but in place of 8's there are 3's. If I put in any other number it seems to work fine. I don't get it.

Thanks, Don

' Define LCD pins
Define  LCD_DREG        PORTA
Define  LCD_DBIT        0
Define  LCD_RSREG       PORTA
Define  LCD_RSBIT       4
Define  LCD_EREG        PORTB
Define  LCD_EBIT        3

OSCCON = $60 ' Set up internal oscillator
x var byte
dtmf var byte
data @1,1,3,0,8,8,6,0,7,3,7,5
TRISB = %11010000
TRISA = %01100000
Pause 500 ' Wait 500mS for LCD to startup
LCDOut $fe, 1 ' Clear LCD screen
Pause 1 ' Wait 1 millisecond
LCDOut $fe,$80 ' Move cursor to the beginning of the first line
LCDOut "DTMF Demo using" ' Display
LCDOut $fe,$c0 ' Move cursor to the beginning of the second line
LCDOut "PIC18F1320" 'Display PIC Lecture
pause 1000
LCDOut $fe, 1 ' Clear LCD screen
LCDOut $fe,$80 ' Move cursor to the beginning of the first line
loop:
      
  for x = 1 to 11
        read x, dtmf
        portb = dtmf
        low portb.5
        pause 100
        high portb.5
        pause 100
        LCDOut DEC1(dtmf)
  next x
        pause 200
        LCDOut $fe, 1 ' Clear LCD screen
        pause 100
        goto loop ' Do it forever
        
        End

[Darrel Taylor]

A couple things...

You're writing the dtmf value to all 8 bit's of PORTB. But PORTB.3 is the LCD's Enable Bit.
So when the data is 8, PORTB.3 gets set High, interfering with the enable line.

You should also turn off the Analog functions since the LCD is on PORTA.
ADCON1 = $7F
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[dbachman]

Thanks Darrel,

Kind of makes sense now that you point out the obvious. Every little bit helps in the learning process though.

Don

[dbachman]

Hi Darrel,

How do I just write to the 4 bits I am using?

[Archangel]

Hi Darrel,

How do I just write to the 4 bits I am using?

Hi Don,
PortB.3 is in the lower 4 bits you are using, you might think good thoughts of moving the E bit to b.4 and then you can address the lower bits as individuals or read the entire port and mask out the upper bits after reading them.

[dbachman]

Hi Joe,

I did do something like that. I moved it to Porta bit 7. Just sittin there anyway. How do you read the entire port - better yet, how would you masked out the bits. I am still in a steep learning curve so please bear with me. Is it like this?

DTMF = DTMF & %00001111 ' isolate lower 4 bits

Thanks, Don