Problem with 10-bit A/D conversion - PIC18F2455 - LCD

[Kuba230]

Hello,
I have written code for 10-bit A/D conversion with PIC18F2455, but not working properly, value on LCD display is not correct.
I used sample code from melbas written for 10-bit A/D conversion on LCD for PIC18F4550.
I only changed values for define LCD registers and bits.
http://melabs.com/samples/LABXUSB-18F4550/adci10xu.htm
I using 20MHz external oscillator.

What is problem?


Thank you


Here is my code:

Define LOADER_USED 1
DEFINE OSC 48

' Define LCD registers and bits
Define LCD_DREG PORTB
Define LCD_DBIT 4
Define LCD_RSREG PORTC
Define LCD_RSBIT 7
Define LCD_EREG PORTC
Define LCD_EBIT 6
DEFINE LCD_BITS 4 ' 4-bit data bus
DEFINE LCD_LINES 2 ' LCD - 2 lines


' Define ADCIN parameters

Define ADC_BITS 10 ' Set number of bits in result
Define ADC_CLOCK 3 ' Set clock source (3=rc)
Define ADC_SAMPLEUS 50 ' Set sampling time in uS


adval var word ' Create adval to store result

TRISA = %11111111 ' Set PORTA to all input
ADCON1 = %00001010 ' Set PORTA analog...
ADCON2 = %10000000 ' ...and right justify result

Pause 500 ' Wait .5 second

loop: ADCIN 0, adval ' Read channel 0 to adval
Lcdout $fe, 1 ' Clear LCD
Lcdout "Value: ", DEC adval ' Display the decimal value
Pause 100 ' Wait .1 second
Goto loop ' Do it forever
End

[richard]

ADCON2 = %10000000 ' ...and right justify result

and set the conversion clock to fosc/2
way out of specs


ADCON2 = %10000011 ' ...and right justify result and use frc

[Kuba230]

I changed
ADCON2 = %10000000

to

ADCON2 = %10000011

it is still the same

[mackrackit]

What is your ADC source and how is it connected?
What are the current readings and what are the expected readings?

[Kuba230]

Source is pressure sensor (output 0 - 1V), wchich is normaly working with 10-bit A/D - PIC16F877 conection.
I built conection with PIC18F2455, but not working properly.

[Kuba230]

Problem is solved, I changed LCD display, it is OK.

Thanks for your help.